농부지기

1. MainActivity.java

package com.example.farmer.keypadall;

import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.TextView;
import android.widget.Toast;

public class MainActivity extends AppCompatActivity {

    EditText arithmetic;
    TextView result;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        arithmetic = (EditText)findViewById(R.id.et_arithmetic);
        result      = (TextView)findViewById(R.id.tv_result);

        ((TextView)findViewById(R.id.tv_mqrquee)).setSelected(true);

        //arithmetic.requestFocus();  //포커스 주기
        arithmetic.setFocusableInTouchMode(false); // 결과 box에 edit막기 : ok
        arithmetic.setKeyListener(null);  //key 가 안눌림. 하지만 keypad가 보임
    }

    //---------------------------------------------------------------------------
    // 사칙연산자 클릭 시
    //   - 사칙연산자가 중복 시 최종연산자로 대체
    //---------------------------------------------------------------------------
    public void arithmeticOrganOnClick(View view){
        String sCurrNum = arithmetic.getText().toString();

        if (sCurrNum.length() == 0)  return;

        String lastChar = sCurrNum.substring(sCurrNum.length()-1, sCurrNum.length());
        if ("+-*/".indexOf(lastChar) >= 0){
            arithmetic.setText( sCurrNum.substring(0, sCurrNum.length()-1) + ((Button)view).getText());
        }else{
            arithmetic.setText( sCurrNum + ((Button)view).getText());
        }
    }

    //---------------------------------------------------------------------------
    //  숫자 클릭 시
    //---------------------------------------------------------------------------
    public void numberOnClick(View view){
        arithmetic.setText( arithmetic.getText().toString() + ((Button)view).getText());
    }
    //---------------------------------------------------------------------------
    //  소수점 클릭 시
    //---------------------------------------------------------------------------
    public void pointOnClick(View view){
        arithmetic.setText( arithmetic.getText().toString() + ((Button)view).getText());
    }

    //---------------------------------------------------------------------------
    //  BackClear 버튼 클릭 시
    //---------------------------------------------------------------------------
    public void oneCharClearOnClick(View view){
        String sCurrNum = arithmetic.getText().toString();  //? getText() : Return이 Editable ?

        //Log.d("farm-1", sNum1);  //?log가 안보임 ?
        if (sCurrNum.length() > 0) {
            //Log.d("farm-2", sNum1);
            sCurrNum = sCurrNum.substring(0, sCurrNum.length() - 1);
            //Log.d("farm-3", sNum1);
            arithmetic.setText(sCurrNum);

            //포커스를 맨 뒤로 하기
            //Editable editable = arithmetic.getText();
            //Selection.setSelection(editable, editable.length());
        }
    }

    //---------------------------------------------------------------------------
    //  Clear 버튼 클릭 시
    //---------------------------------------------------------------------------
    public void allClearOnClick(View view){
        arithmetic.setText("");
        result.setText("");
    }

    //---------------------------------------------------------------------------
    // ()괄호 버튼 클릭 시
    // 1. 숫자 다음에 (  여는 괄호는 올 수 없음
    // 2. 사칙연산자 다음이 ) 닫는 괄호는 올 수 없음
    //---------------------------------------------------------------------------
    public void bracketOnclick(View view){
        String sCurrNum = arithmetic.getText().toString();

        switch (view.getId()){
            case R.id.bt_braketLeft:
                if (sCurrNum.length() > 0) {
                    String lastChar = sCurrNum.substring(sCurrNum.length()-1, sCurrNum.length());
                    Toast.makeText(MainActivity.this, "lastChar=" + lastChar, Toast.LENGTH_SHORT).show();
                    if ("0123456789".indexOf(lastChar) >= 0) return;
                }
                break;
            case R.id.bt_braketRight:
                if (sCurrNum.length() > 0) {
                    String lastChar = sCurrNum.substring(sCurrNum.length()-1, sCurrNum.length());
                    if ("+0*/".indexOf(lastChar) >= 0) return;
                }
                break;
        }

        arithmetic.setText( arithmetic.getText().toString() + ((Button)view).getText());
    }

    //---------------------------------------------------------------------------
    //  계산 버튼 클릭 시
    //---------------------------------------------------------------------------
    public void calculatorOnClick(View view) throws Exception{
        Calculator calculator = new Calculator();

        String sCurrNum = arithmetic.getText().toString();
        String resultVal = calculator.bracketCalMain(sCurrNum);
        result.setText(resultVal);
    }
}

2. Calculator.java

package com.example.farmer.keypadall;

import java.util.LinkedList;
import java.util.Queue;
import java.math.BigDecimal;

/**
* Created by kyh on 2017-01-02.
*/

public class Calculator {
    //------------------------------------------------------------------------
    // 괄호 까지 존재하는 사칙연사
    //------------------------------------------------------------------------
    @SuppressWarnings({ "rawtypes", "unchecked" })
    public static String bracketCalMain(String sNumList) throws Exception{
        //0. ( ) 괄호 갯수 검증
        if (checkBracket(sNumList) == false) return "괄호 () 갯수가 Match되지 않습니다.";

        // 1. 1차 문자열 Parsing
        Queue firstQueue = new LinkedList();
        firstQueue = stringParsing(sNumList);
        System.out.println("----------------------------------------------");
        System.out.println("괄호 1차  => " + firstQueue.toString());

        // 2. 2차 괄호안 계산
        Queue secondQueue = new LinkedList();
        String oneChar;
        while(firstQueue.peek() != null){
            oneChar  = firstQueue.poll().toString();
            //System.out.println("괄호  => " + oneChar);

            if ("()".indexOf(oneChar) >= 0){
                //괄호안 계산 (firstQueue)
                secondQueue.offer(braketInCal(firstQueue));
            }else{
                secondQueue.offer(oneChar);
            }
        }

        //3. Queue에 저장 된 값 중  곱셈. 나눗셈 계산
        secondQueue = multiplyDivideCal(secondQueue);

        //4. Queue에 저장 된 값 중  덧셈. 뺄샘 계산
        String sResult = addSubtractCal(secondQueue);
        System.out.println("괄호 최종결과 => " + sResult);
        return sResult;
    }

    //( ) 괄호 갯수 검증
    public static boolean checkBracket(String sNumList){
        int count1=0, count2=0;
        for(int i=0; i<sNumList.length(); i++){
            if ("(".equals(sNumList.substring(i, i+1))){
                count1 ++;
            }else if (")".equals(sNumList.substring(i, i+1))){
                count2 ++;
            }
        }

        if (count1 == count2)
            return true;
        else{
            System.out.println("괄호 () 갯수가 Match되지 않습니다.");
            return false;
        }
    }

    //------------------------------------------------------------------------
    // 1차. 문자열 Parsing
    //------------------------------------------------------------------------
    @SuppressWarnings({ "rawtypes", "unchecked" })
    public static Queue stringParsing(String sNumList){
        String sOneNum = "";  //하나의 숫자열
        Queue firstQueue = new LinkedList();
        for(int i=0; i<sNumList.length(); i++){
            String oneChar = sNumList.substring(i, i+1);
            if ("+-*/()".indexOf(oneChar) >= 0 ){

                // 3+(3  과 같이   4칙연산자와 괄호가 동시에 존재 하는 경우 때문
                if (!"".equals(sOneNum)) firstQueue.offer(sOneNum);   
                firstQueue.offer(oneChar);
                sOneNum = "";
            }else{
                sOneNum += oneChar;

                if (i+1 == sNumList.length()){
                    firstQueue.offer(sOneNum);
                }
            }
        }
        return firstQueue;
    }

    //------------------------------------------------------------------------
    // 2차. 괄호 내부 계산 (재귀적 호출)
    //------------------------------------------------------------------------
    @SuppressWarnings({ "unchecked", "rawtypes" })
    public static String braketInCal(Queue firstQueue) throws Exception{
        String oneChar;
        //1. 괄호 내부에 존재 하는 값을 Queue에 저장
        Queue secondQueue = new LinkedList();
        while(firstQueue.peek() != null){
            oneChar  = firstQueue.poll().toString();
            if ("(".equals(oneChar)){
                //괄호안 계산 (firstQueue)
                secondQueue.offer(braketInCal(firstQueue));
            }else if (")".equals(oneChar)){
                break; //닫기 괄호가 나오면 stop
            }else{
                secondQueue.offer(oneChar);
            }
        }
        System.out.println("괄호 2차  => " + secondQueue.toString());

        //2. Queue에 저장 된 값 중  곱셈. 나눗셈 계산
        secondQueue = multiplyDivideCal(secondQueue);

        //3. Queue에 저장 된 값 중  덧셈. 뺄샘 계산
        String sResult = addSubtractCal(secondQueue);

        return sResult;
    }


    //------------------------------------------------------------------------
    // 곱셈, 나눗셈 계산
    //------------------------------------------------------------------------
    @SuppressWarnings({ "rawtypes", "unchecked" })
    public static Queue multiplyDivideCal(Queue inQueue) throws Exception{
        Queue outQueue = new LinkedList();
        String oneChar;
        String sNum1 = "", sNum2 = "", sResult = "";
        String operator = "";
        BigDecimal nResult = new BigDecimal("0");
        while(inQueue.peek() != null){
            oneChar  = inQueue.poll().toString();

            if ("+-".indexOf(oneChar) >= 0 ){
                outQueue.offer(sNum1);
                outQueue.offer(oneChar);
                sNum1 = "";
            }else if ("*/".indexOf(oneChar) >= 0 ) {
                operator = oneChar;
            }else{
                if ("".equals(sNum1)){
                    sNum1 = oneChar;
                }else if ("".equals(sNum2)) {
                    sNum2 = oneChar;
                    if ("*".equals(operator)) {
                        nResult = (new BigDecimal(sNum1)).multiply(new BigDecimal(sNum2));
                    }else if ("/".equals(operator)) {
                        if ("0".equals(sNum2)){
                            throw new Exception("나눗셈 분모에 0 이 존재 합니다.");
                        }

                        nResult = (new BigDecimal(sNum1)).divide(new BigDecimal(sNum2), 6, BigDecimal.ROUND_UP);
                    }
                    sResult  = String.valueOf(nResult);


                    sNum1    = sResult;
                    sNum2    = "";
                    operator = "";
                }
            }

            if (inQueue.peek() == null) outQueue.offer(sNum1);
        }
        return outQueue;
    }


    //------------------------------------------------------------------------
    // 덧셈. 뺄샘 계산
    //------------------------------------------------------------------------
    @SuppressWarnings({ "rawtypes" })
    public static String addSubtractCal(Queue inQueue){
        String operator = "";
        String oneChar  = "";
        BigDecimal nResult  = new BigDecimal(inQueue.poll().toString());
        while(inQueue.peek() != null){
            oneChar  = inQueue.poll().toString();

            if ("+-".indexOf(oneChar) >= 0 ){
                operator = oneChar;
            }else{
                if ("+".equals(operator)){
                    nResult = nResult.add(new BigDecimal(oneChar));
                }else if ("-".equals(operator)){
                    nResult = nResult.subtract(new BigDecimal(oneChar));
                }
                operator = "";
            }
        }
        return nResult.toString();
    }
}

3. activity_main.xml 

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"

    android:id="@+id/activity_keypad"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:background="#d1cdcd"
    android:orientation="vertical"
    tools:context="com.example.farmer.keypadall.MainActivity">

    <!--   0차 : mqrquee -->
    <RelativeLayout
        android:layout_width="match_parent"
        android:layout_height="0dp"
        android:background="#00ffffff"
        android:layout_weight="1">

        <TextView
            android:id="@+id/tv_mqrquee"
            android:textSize="30dp"
            android:padding="10dp"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:layout_alignParentLeft="true"
            android:layout_centerInParent="true"
            android:text="농부의 4칙연산 계산기. 자체개발 완료..  으미 힘든거~~~~~~"
            android:ellipsize="marquee"
            android:focusable="true"
            android:marqueeRepeatLimit="marquee_forever"
            android:singleLine="true"/>
    </RelativeLayout>
    <!--  1차 : 산술식 -->
    <RelativeLayout
        android:layout_width="match_parent"
        android:layout_height="0dp"
        android:background="#b4b2b7"
        android:layout_weight="1">

        <TextView
            android:id="@+id/tv_num"
            android:padding="10dp"
            android:layout_width="90dp"
            android:layout_height="wrap_content"
            android:layout_alignParentLeft="true"
            android:layout_centerInParent="true"
            android:text="4칙 연산식"/>

        <EditText
            android:id="@+id/et_arithmetic"
            android:layout_marginRight="10dp"
            android:layout_width="match_parent"
            android:layout_height="30dp"
            android:hint="4칙 연산식을 입력 하시오."
            android:paddingLeft="10dp"
            android:background="#ffffff"
            android:layout_centerInParent="true"
            android:layout_toRightOf="@+id/tv_num" />

    </RelativeLayout>

    <!--   2차 : 결과 -->
    <RelativeLayout
        android:layout_width="match_parent"
        android:layout_height="0dp"
        android:background="#d7c6ed"
        android:layout_weight="1">

        <TextView
            android:id="@+id/tv_resultLabel"
            android:padding="10dp"
            android:layout_width="90dp"
            android:layout_height="wrap_content"
            android:layout_centerInParent="true"
            android:layout_alignParentLeft="true"
            android:text="Result"/>

        <TextView
            android:id="@+id/tv_result"
            android:textSize="20dp"
            android:layout_marginRight="10dp"
            android:layout_width="match_parent"
            android:layout_height="30dp"
            android:text=""
            android:paddingLeft="10dp"
            android:background="#e4e4dd"
            android:layout_centerInParent="true"
            android:layout_toRightOf="@+id/tv_resultLabel"/>

    </RelativeLayout>

    <!--   3차 : 빈 공백 -->
    <RelativeLayout
        android:layout_width="match_parent"
        android:layout_height="0dp"
        android:background="#fcfcfc"
        android:layout_weight="0.2">
    </RelativeLayout>

    <!--   4차 : 기타   C, ( ) /   "#6a00ff" -->
    <RelativeLayout
        android:layout_width="match_parent"
        android:layout_height="0dp"
        android:background="@drawable/border_layout"
        android:layout_weight="1">

        <Button
            android:id="@+id/bt_clear"
            android:onClick="allClearOnClick"
            android:text="C"
            android:textSize="30dp"
            android:layout_width="75dp"
            android:layout_height="45dp"
            android:layout_marginLeft="30dp"
            android:layout_alignParentLeft="true"
            android:layout_centerVertical="true"
            android:background="@drawable/border_calbutton"/>
        <Button
            android:id="@+id/bt_braketLeft"
            android:onClick="bracketOnclick"
            android:text="("
            android:textSize="30dp"
            android:layout_width="75dp"
            android:layout_height="45dp"
            android:layout_toRightOf="@+id/bt_clear"
            android:layout_centerVertical="true"
            android:background="@drawable/border_calbutton"/>
        <Button
            android:id="@+id/bt_braketRight"
            android:onClick="bracketOnclick"
            android:text=")"
            android:textSize="30dp"
            android:layout_width="75dp"
            android:layout_height="45dp"
            android:layout_toRightOf="@+id/bt_braketLeft"
            android:layout_centerVertical="true"
            android:background="@drawable/border_calbutton"/>
        <Button
            android:id="@+id/bt_divide"
            android:onClick="arithmeticOrganOnClick"
            android:text="/"
            android:textSize="30dp"
            android:layout_width="75dp"
            android:layout_height="45dp"
            android:layout_toRightOf="@+id/bt_braketRight"
            android:layout_centerVertical="true"
            android:background="@drawable/border_calbutton"/>

    </RelativeLayout>

    <!--   5차 : 7,8,9, *  -->
    <RelativeLayout
        android:layout_width="match_parent"
        android:layout_height="0dp"
        android:background="@drawable/border_layout"
        android:layout_weight="1">

        <Button
            android:id="@+id/bt_seven"
            android:onClick="numberOnClick"
            android:text="7"
            android:textSize="30dp"
            android:layout_width="75dp"
            android:layout_height="match_parent"
            android:layout_marginLeft="30dp"
            android:layout_alignParentLeft="true"
            android:layout_centerVertical="true" />
        <Button
            android:id="@+id/bt_eight"
            android:onClick="numberOnClick"
            android:text="8"
            android:textSize="30dp"
            android:layout_width="75dp"
            android:layout_height="match_parent"
            android:layout_toRightOf="@+id/bt_seven"
            android:layout_centerVertical="true" />
        <Button
            android:id="@+id/bt_nine"
            android:onClick="numberOnClick"
            android:text="9"
            android:textSize="30dp"
            android:layout_width="75dp"
            android:layout_height="match_parent"
            android:layout_toRightOf="@+id/bt_eight"
            android:layout_centerVertical="true" />
        <Button
            android:id="@+id/bt_multiply"
            android:onClick="arithmeticOrganOnClick"
            android:text="*"
            android:textSize="30dp"
            android:layout_width="75dp"
            android:layout_height="45dp"
            android:layout_toRightOf="@+id/bt_nine"
            android:layout_centerVertical="true"
            android:background="@drawable/border_calbutton"/>

    </RelativeLayout>

    <!--   6차 : 4,5,6,-  -->
    <RelativeLayout
        android:layout_width="match_parent"
        android:layout_height="0dp"
        android:background="@drawable/border_layout"
        android:layout_weight="1">

        <Button
            android:id="@+id/bt_four"
            android:onClick="numberOnClick"
            android:text="4"
            android:textSize="30dp"
            android:layout_width="75dp"
            android:layout_height="match_parent"
            android:layout_marginLeft="30dp"
            android:layout_alignParentLeft="true"
            android:layout_centerVertical="true" />
        <Button
            android:id="@+id/bt_five"
            android:onClick="numberOnClick"
            android:text="5"
            android:textSize="30dp"
            android:layout_width="75dp"
            android:layout_height="match_parent"
            android:layout_toRightOf="@+id/bt_four"
            android:layout_centerVertical="true" />
        <Button
            android:id="@+id/bt_six"
            android:onClick="numberOnClick"
            android:text="6"
            android:textSize="30dp"
            android:layout_width="75dp"
            android:layout_height="match_parent"
            android:layout_toRightOf="@+id/bt_five"
            android:layout_centerVertical="true" />
        <Button
            android:id="@+id/bt_minus"
            android:onClick="arithmeticOrganOnClick"
            android:text="-"
            android:textSize="30dp"
            android:layout_width="75dp"
            android:layout_height="45dp"
            android:layout_toRightOf="@+id/bt_six"
            android:layout_centerVertical="true"
            android:background="@drawable/border_calbutton"/>

    </RelativeLayout>

    <!--   7차 : 1,2,3,+  -->
    <RelativeLayout
        android:layout_width="match_parent"
        android:layout_height="0dp"
        android:background="@drawable/border_layout"
        android:layout_weight="1">

        <Button
            android:id="@+id/bt_one"
            android:onClick="numberOnClick"
            android:text="1"
            android:textSize="30dp"
            android:layout_width="75dp"
            android:layout_height="match_parent"
            android:layout_marginLeft="30dp"
            android:layout_alignParentLeft="true"
            android:layout_centerVertical="true" />
        <Button
            android:id="@+id/bt_two"
            android:onClick="numberOnClick"
            android:text="2"
            android:textSize="30dp"
            android:layout_width="75dp"
            android:layout_height="match_parent"
            android:layout_toRightOf="@+id/bt_one"
            android:layout_centerVertical="true" />
        <Button
            android:id="@+id/bt_three"
            android:onClick="numberOnClick"
            android:text="3"
            android:textSize="30dp"
            android:layout_width="75dp"
            android:layout_height="match_parent"
            android:layout_toRightOf="@+id/bt_two"
            android:layout_centerVertical="true" />
        <Button
            android:id="@+id/bt_plus"
            android:onClick="arithmeticOrganOnClick"
            android:text="+"
            android:textSize="30dp"
            android:layout_width="75dp"
            android:layout_height="45dp"
            android:layout_toRightOf="@+id/bt_three"
            android:layout_centerVertical="true"
            android:background="@drawable/border_calbutton"/>

    </RelativeLayout>

    <!--   8차 : 0, . <- =  -->
    <RelativeLayout
        android:layout_width="match_parent"
        android:layout_height="0dp"
        android:background="@drawable/border_layout"
        android:layout_weight="1">

        <Button
            android:id="@+id/bt_zero"
            android:onClick="numberOnClick"
            android:text="0"
            android:textSize="30dp"
            android:layout_width="75dp"
            android:layout_height="match_parent"
            android:layout_marginLeft="30dp"
            android:layout_alignParentLeft="true"
            android:layout_centerVertical="true" />
        <Button
            android:id="@+id/bt_point"
            android:onClick="pointOnClick"
            android:text="."
            android:textSize="30dp"
            android:layout_width="75dp"
            android:layout_height="45dp"
            android:layout_toRightOf="@+id/bt_zero"
            android:layout_centerVertical="true"
            android:background="@drawable/border_calbutton"/>
        <Button
            android:id="@+id/bt_back"
            android:onClick="oneCharClearOnClick"
            android:text="←"
            android:textSize="30dp"
            android:layout_width="75dp"
            android:layout_height="45dp"
            android:layout_toRightOf="@+id/bt_point"
            android:layout_centerVertical="true"
            android:background="@drawable/border_calbutton"/>
        <Button
            android:id="@+id/bt_calculator"
            android:onClick="calculatorOnClick"
            android:text="="
            android:textSize="30dp"
            android:layout_width="75dp"
            android:layout_height="45dp"
            android:layout_toRightOf="@+id/bt_back"
            android:layout_centerVertical="true"
            android:background="@drawable/border_calbutton"/>

    </RelativeLayout>

    <!--   9차 : 빈공백 -->
    <RelativeLayout
        android:layout_width="match_parent"
        android:layout_height="0dp"
        android:background="#00ffffff"
        android:layout_weight="0.5">
    </RelativeLayout>
</LinearLayout>

4. drawable/border_calbutton.xml

<?xml version="1.0" encoding="utf-8"?>
<layer-list xmlns:android="http://schemas.android.com/apk/res/android">
    <!-- 설정된 위젯의 background를 설정
         1. 아래 body설정 부분에서 전체영역이 설정 되면  이 background는 아무 표시가 안난다.
         2. 아래 body설정 부분에서 top,bottom,left,right에 2dp씩 설정 되었기에
            이 2dp만큼  아래 부분에 설정된 모양(rectangle)과 색깔(#f9c7cc)이 보인다.
    -->
    <item>
        <shape android:shape="rectangle">
            <solid android:color="#f9c7cc" />
        </shape>
    </item>

    <!-- 설정된 위젯의 Body를 설정
         1. top,bottom,left,right 에 2dp 설정
         2. shape : body를 사각형으로 설정
         3. color : body에 color지정
    -->
    <item android:top="2dp" android:bottom="2dp" android:left="2dp" android:right="2dp">
        <shape android:shape="rectangle">
            <solid android:color="#d4d2d2" />
        </shape>
    </item>
</layer-list>

5. drawable/border_layout.xml 

<?xml version="1.0" encoding="utf-8"?>
<layer-list xmlns:android="http://schemas.android.com/apk/res/android">
    <!-- 설정된 위젯의 background를 설정
         1. 아래 body설정 부분에서 전체영역이 설정 되면  이 background는 아무 표시가 안난다.
         2. 아래 body설정 부분에서 top, bottom에 2dp씩 설정 되었기에
            이 2dp만큼  아래 부분에 설정된 모양(oval)과 색깔(#6a00ff)이 보인다.
    -->
    <item>
        <shape android:shape="oval">
            <solid android:color="#6a00ff" />
        </shape>
    </item>

    <!-- 설정된 위젯의 Body를 설정
         1. top, bottom 에 2dp 설정
         2. shape : body를 사각형으로 설정
         3. color : body에 color지정
    -->
    <item android:top="2dp" android:bottom="2dp">
        <shape android:shape="rectangle">
            <solid android:color="#eeffffff" />
        </shape>
    </item>
</layer-list>

6. values/colors.xml

<?xml version="1.0" encoding="utf-8"?>
<resources>
    <color name="colorPrimary">#3F51B5</color>
    <color name="colorPrimaryDark">#303F9F</color>
    <color name="colorAccent">#FF4081</color>
    <drawable name="bg_select">#2196F3</drawable>
    <drawable name="bg">#EEEEEE</drawable>
</resources>

  1. MainActivity.java

 package com.example.farmer.queuecalculatorstep;

import android.graphics.Color;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.Gravity;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.TextView;
import android.widget.Toast;

import java.math.BigDecimal;
import java.util.LinkedList;
import java.util.Queue;

public class MainActivity extends AppCompatActivity {
    Queue<String> firstQueue = new LinkedList();
    Queue<String> secondQueue = new LinkedList();

    TextView tv_queue1;
    TextView tv_queue2;
    TextView tv_pop1;
    TextView tv_pop2;
    TextView tv_onecalulator;
    TextView tv_result;

    int stepIdx = -1;
    int seq = 0;
    String sResult;

    @Override
    protected void onCreate(Bundle savedInstanceState){
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        //public member 생성
        tv_queue1 = (TextView)findViewById(R.id.tv_queue1);
        tv_queue2 = (TextView)findViewById(R.id.tv_queue2);
        tv_pop1 = (TextView)findViewById(R.id.tv_pop1);
        tv_pop2 = (TextView)findViewById(R.id.tv_pop2);
        tv_onecalulator = (TextView)findViewById(R.id.tv_onecalulator);
        tv_result = (TextView)findViewById(R.id.tv_result);

        //Button Listener 연동
        Button btnStep  = (Button)findViewById(R.id.btnStep);
        Button btnClear = (Button)findViewById(R.id.btnClear);
        btnStep.setOnClickListener(calOnclickListener);
        btnClear.setOnClickListener(clearOnclickListener);
    }

    Button.OnClickListener calOnclickListener = new View.OnClickListener(){
        @Override
        public void onClick(View view) {
            stepIdx++;
            seq = 0;
            calculatorMain();

            //tv_result.setText(sResult);
        }
    };

    //------------------------------------------------------------------------
    // 사칙연사 시작
    //------------------------------------------------------------------------
    @SuppressWarnings({ "rawtypes", "unchecked" })
    public void calculatorMain(){
        firstQueue.clear();
        secondQueue.clear();

        //1. 산술식을 queue에 넣기
        stringParsing();
        tv_queue1.setText(firstQueue.toString());
        if (stepIdx==0) return;  //step 1

        //2. Queue에 저장 된 값 중  곱셈. 나눗셈 계산
        multiplyDivideCal();

        //3 Queue에 저장 된 값 중  덧셈. 뺄샘 계산
        sResult = addSubtractCal();
        //System.out.println("괄호 최종결과 => " + sResult);
    }

    //------------------------------------------------------------------------
    // 1차. 문자열 Parsing
    //------------------------------------------------------------------------
    @SuppressWarnings({ "rawtypes", "unchecked" })
    public Queue stringParsing(){
        String sNumList = ((EditText)findViewById(R.id.et_arithmetic)).getText().toString();
        String sOneNum = "";  //하나의 숫자열
        for(int i=0; i<sNumList.length(); i++){
            String oneChar = sNumList.substring(i, i+1);
            if ("+-*/()".indexOf(oneChar) >= 0 ){

                // 3+(3  과 같이   4칙연산자와 괄호가 동시에 존재 하는 경우 때문
                if (!"".equals(sOneNum)) firstQueue.offer(sOneNum);   
                firstQueue.offer(oneChar);
                sOneNum = "";
            }else{
                sOneNum += oneChar;

                if (i+1 == sNumList.length()){
                    firstQueue.offer(sOneNum);
                }
            }
        }
        return firstQueue;
    }

    //------------------------------------------------------------------------
    // 곱셈, 나눗셈 계산
    //------------------------------------------------------------------------
    @SuppressWarnings({ "rawtypes", "unchecked" })
    public Queue multiplyDivideCal(){
        String oneChar;
        String sNum1 = "", sNum2 = "", sResult = "";
        String operator = "";
        BigDecimal nResult = new BigDecimal("0");
        while(firstQueue.peek() != null){
            oneChar  = firstQueue.poll().toString();
            seq++;
            if (stepIdx == seq) tv_queue1.setText(firstQueue.toString());  //step
            if (stepIdx == seq) tv_pop1.setText(oneChar);  //step
            if (stepIdx == seq) tv_pop2.setText("");

            if ("+-".indexOf(oneChar) >= 0 ){
                secondQueue.offer(sNum1);
                secondQueue.offer(oneChar);
                sNum1 = "";
            }else if ("*/".indexOf(oneChar) >= 0 ) {
                operator = oneChar;
            }else{
                if ("".equals(sNum1)){
                    sNum1 = oneChar;
                }else if ("".equals(sNum2)) {
                    sNum2 = oneChar;
                    if ("*".equals(operator)) {
                        nResult = (new BigDecimal(sNum1)).multiply(new BigDecimal(sNum2));
                    }else if ("/".equals(operator)) {
                        nResult = (new BigDecimal(sNum1)).divide(new BigDecimal(sNum2), 0, BigDecimal.ROUND_UP);
                    }

                    if (stepIdx == seq) tv_pop2.setText(sNum1 + " " + operator + " " + sNum2);
                    sResult  = String.valueOf(nResult);

                    sNum1    = sResult;
                    sNum2    = "";
                    operator = "";
                }
            }

            if (firstQueue.peek() == null) secondQueue.offer(sNum1);

            if (stepIdx == seq) tv_queue2.setText(secondQueue.toString());  //step
        }
        return secondQueue;
    }

    //------------------------------------------------------------------------
    // 덧셈. 뺄샘 계산
    //------------------------------------------------------------------------
    @SuppressWarnings({ "rawtypes" })
    public String addSubtractCal(){
        String operator = "";
        String oneChar  = "";
        //if (secondQueue.peek() == null) return "";
        //System.out.println("secondQueue.poll().toString()=" + secondQueue.toString());
        BigDecimal nResult  = new BigDecimal(secondQueue.poll().toString());
        seq++;
        if (stepIdx == seq) tv_queue2.setText(secondQueue.toString());  //step
        if (stepIdx == seq) tv_pop1.setText(nResult.toString());  //step
        if (stepIdx == seq) tv_pop2.setText("");

        while(secondQueue.peek() != null){
            oneChar  = secondQueue.poll().toString();
            seq++;
            if (stepIdx == seq) tv_queue2.setText(secondQueue.toString());  //step
            if (stepIdx == seq) tv_pop1.setText(oneChar);  //step
            if (stepIdx == seq) tv_pop2.setText("");

            if ("+-".indexOf(oneChar) >= 0 ){
                operator = oneChar;
            }else{
                if (stepIdx == seq) tv_pop2.setText(nResult + " " + operator + " " + oneChar);
                if ("+".equals(operator)){
                    nResult = nResult.add(new BigDecimal(oneChar));
                }else if ("-".equals(operator)){
                    nResult = nResult.subtract(new BigDecimal(oneChar));
                }
                operator = "";
            }
        }
        return nResult.toString();
    }

    Button.OnClickListener clearOnclickListener = new View.OnClickListener(){
        @Override
        public void onClick(View view) {
            stepIdx = -1;
            seq = 0;
            tv_queue1.setText("");
            tv_queue2.setText("");
            tv_pop1.setText("");
            tv_pop2.setText("");
            tv_onecalulator.setText("");
            tv_result.setText("");

            //Toast toast = Toast(getApplicationContext());
            //toast.setText(sResult);
            //toast.setDuration(Toast.LENGTH_LONG);

            Toast toast = Toast.makeText(getApplicationContext(), sResult, Toast.LENGTH_SHORT);
            toast.setGravity(Gravity.TOP | Gravity.RIGHT, 0, 0);
            View viewToast = toast.getView();

            //Toast BackgroundColor 변경
            //color표기시 xml에서는 "#ffffff"로 하지만
            //java코드에서는 아래와 같이 rgb로 변환하여 사용해줘야 한다.
            viewToast.setBackgroundColor(Color.rgb(255,0,255));

            //Toast Font Color변경
            TextView tvToast = (TextView)viewToast.findViewById(android.R.id.message);
            tvToast.setTextColor(Color.RED);

            toast.show();

            //Toast.makeText(getApplicationContext(), sResult, Toast.LENGTH_LONG).show();
            tv_result.setText(sResult);
        }
    };
}

  2. activity_main.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"

    android:id="@+id/activity_keypad"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:background="#fde002"
    android:orientation="vertical"
    tools:context="com.example.farmer.queuecalculatorstep.MainActivity">>

    <!--  1차 : 산술식 -->
    <RelativeLayout
        android:layout_width="match_parent"
        android:layout_height="0dp"
        android:background="#b4b2b7"
        android:layout_weight="1">

        <TextView
            android:id="@+id/tv_num"
            android:padding="10dp"
            android:layout_width="90dp"
            android:layout_height="wrap_content"
            android:layout_alignParentLeft="true"
            android:layout_centerInParent="true"
            android:text="4칙 연산식"/>

        <EditText
            android:id="@+id/et_arithmetic"
            android:text="16+12/1-2*2"
            android:layout_marginRight="10dp"
            android:layout_width="match_parent"
            android:layout_height="30dp"
            android:paddingLeft="10dp"
            android:background="#ffffff"
            android:layout_centerInParent="true"
            android:layout_toRightOf="@+id/tv_num" />

    </RelativeLayout>

    <!--  2차 : queue1 -->
    <RelativeLayout
        android:layout_width="match_parent"
        android:layout_height="0dp"
        android:background="#e9e0f7"
        android:layout_marginTop="5dp"
        android:layout_weight="1">

        <TextView
            android:id="@+id/tv_lavel1"
            android:padding="10dp"
            android:layout_width="90dp"
            android:layout_height="wrap_content"
            android:layout_alignParentLeft="true"
            android:layout_centerInParent="true"
            android:text="queue 1"/>

        <TextView
            android:id="@+id/tv_queue1"
            android:padding="10dp"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:paddingLeft="10dp"
            android:layout_marginRight="10dp"
            android:layout_centerInParent="true"
            android:layout_toRightOf="@+id/tv_lavel1"
            android:background="#ffffff"
            android:text="queue 1"/>
    </RelativeLayout>

    <!--  3차 : queue2 -->
    <RelativeLayout
        android:layout_width="match_parent"
        android:layout_height="0dp"
        android:background="#e9e0f7"
        android:layout_marginTop="5dp"
        android:layout_weight="1">

        <TextView
            android:id="@+id/tv_lavel2"
            android:padding="10dp"
            android:layout_width="90dp"
            android:layout_height="wrap_content"
            android:layout_alignParentLeft="true"
            android:layout_centerInParent="true"
            android:text="queue 2"/>

        <TextView
            android:id="@+id/tv_queue2"
            android:padding="10dp"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:paddingLeft="10dp"
            android:layout_marginRight="10dp"
            android:layout_centerInParent="true"
            android:layout_toRightOf="@+id/tv_lavel2"
            android:background="#ffffff"
            android:text="queue 2"/>
    </RelativeLayout>

    <!--  5차 : pop1 -->
    <RelativeLayout
        android:layout_width="match_parent"
        android:layout_height="0dp"
        android:background="#e3ebf4"
        android:layout_marginTop="5dp"
        android:layout_weight="1">

        <TextView
            android:id="@+id/tv_poplavel1"
            android:padding="10dp"
            android:layout_width="90dp"
            android:layout_height="wrap_content"
            android:layout_alignParentLeft="true"
            android:layout_centerInParent="true"
            android:text="pop"/>

        <TextView
            android:id="@+id/tv_pop1"
            android:padding="10dp"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:paddingLeft="10dp"
            android:layout_marginRight="10dp"
            android:layout_centerInParent="true"
            android:layout_toRightOf="@+id/tv_poplavel1"
            android:background="#ffffff"
            android:text=""/>
    </RelativeLayout>

    <!--  5차 : pop2 -->
    <RelativeLayout
        android:layout_width="match_parent"
        android:layout_height="0dp"
        android:background="#e3ebf4"
        android:layout_marginTop="5dp"
        android:layout_weight="1">

        <TextView
            android:id="@+id/tv_poplavel3"
            android:padding="10dp"
            android:layout_width="90dp"
            android:layout_height="wrap_content"
            android:layout_alignParentLeft="true"
            android:layout_centerInParent="true"
            android:text="계산"/>

        <TextView
            android:id="@+id/tv_pop2"
            android:padding="10dp"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:paddingLeft="10dp"
            android:layout_marginRight="10dp"
            android:layout_centerInParent="true"
            android:layout_toRightOf="@+id/tv_poplavel3"
            android:background="#ffffff"
            android:text=""/>
    </RelativeLayout>

    <!--  6차 : 4칙연산 하나 계산 -->
    <RelativeLayout
        android:layout_width="match_parent"
        android:layout_height="0dp"
        android:background="#dbdee1"
        android:layout_marginTop="5dp"
        android:layout_weight="1">

        <TextView
            android:id="@+id/tv_onelavel"
            android:padding="10dp"
            android:layout_width="90dp"
            android:layout_height="wrap_content"
            android:layout_alignParentLeft="true"
            android:layout_centerInParent="true"
            android:text="4칙연산"/>

        <TextView
            android:id="@+id/tv_onecalulator"
            android:padding="10dp"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:paddingLeft="10dp"
            android:layout_marginRight="10dp"
            android:layout_centerInParent="true"
            android:layout_toRightOf="@+id/tv_onelavel"
            android:background="#ffffff"
            android:text=""/>
    </RelativeLayout>

    <!--  7차 : 최종 계산 -->
    <RelativeLayout
        android:layout_width="match_parent"
        android:layout_height="0dp"
        android:background="#dbdee1"
        android:layout_marginTop="5dp"
        android:layout_weight="1">

        <TextView
            android:id="@+id/tv_resultlabel"
            android:padding="10dp"
            android:layout_width="90dp"
            android:layout_height="wrap_content"
            android:layout_alignParentLeft="true"
            android:layout_centerInParent="true"
            android:text="결과"/>

        <TextView
            android:id="@+id/tv_result"
            android:padding="10dp"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:paddingLeft="10dp"
            android:layout_marginRight="10dp"
            android:layout_centerInParent="true"
            android:layout_toRightOf="@+id/tv_resultlabel"
            android:background="#ffffff"
            android:text=""/>
    </RelativeLayout>

    <!--  8차 : step -->
    <RelativeLayout
        android:layout_width="match_parent"
        android:layout_height="0dp"
        android:background="#dbdee1"
        android:layout_marginTop="5dp"
        android:layout_weight="1">

        <Button
            android:id="@+id/btnStep"
            android:text="POP"
            android:layout_centerHorizontal="true"
            android:layout_width="wrap_content"
            android:paddingRight="20dp"
            android:layout_height="wrap_content" />

        <Button
            android:id="@+id/btnClear"
            android:text="Clear"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_toRightOf="@id/btnStep" />
    </RelativeLayout>

    <!--   9차 : 빈공백 -->
    <RelativeLayout
        android:layout_width="match_parent"
        android:layout_height="0dp"
        android:background="#ffffff"
        android:layout_weight="0.5">
    </RelativeLayout>
</LinearLayout>