[안드로이드 프로그래밍] 10장 직접 풀어보기 10-3

한빛아카데미 Android Studio를 활용한 안드로이드 프로그래밍 6판

 

p.412 직접 풀어보기 10-3

 

두 수를 입력하고 더하기, 빼기, 곱하기,  나누기 라디오버튼을 선택한 후 <계산하기>를 클릭하면 세컨드 엑티비티에서 계산하고 값을 돌려받는 앱을 작성하라.

 

코드

MainActivity.java

package com.cookandroid.test;

import androidx.appcompat.app.AppCompatActivity;

import android.content.Intent;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.RadioGroup;
import android.widget.Toast;

public class MainActivity extends AppCompatActivity {
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        setTitle("메인 엑티비티");

        final EditText edtNum1 = findViewById(R.id.edtNum1);
        final EditText edtNum2 = findViewById(R.id.edtNum2);
        final RadioGroup rdoGroup = findViewById(R.id.rdoGroup);
        Button btnNewActivity = findViewById(R.id.btnNewActivity);

        btnNewActivity.setOnClickListener(new View.OnClickListener() {
            public void onClick(View v) {

                Intent intent = new Intent(getApplicationContext(), SecondActivity.class);
                switch (rdoGroup.getCheckedRadioButtonId()) {
                    case R.id.rdoAdd:
                        intent.putExtra("Calc", "+");
                        break;
                    case R.id.rdoSub:
                        intent.putExtra("Calc", "-");
                        break;
                    case R.id.rdoMul:
                        intent.putExtra("Calc", "*");
                        break;
                    case R.id.rdoDiv:
                        intent.putExtra("Calc", "/");
                        break;
                    default:
                        break;
                }

                intent.putExtra("Num1",
                        Integer.parseInt(edtNum1.getText().toString()));
                intent.putExtra("Num2",
                        Integer.parseInt(edtNum2.getText().toString()));

                startActivityForResult(intent, 0);
            }
        });
    }

    @Override
    protected void onActivityResult(int requestCode, int resultCode, Intent data) {
        if (resultCode == RESULT_OK) {
            int hap = data.getIntExtra("Hap", 0);
            Toast.makeText(getApplicationContext(), "결과 :" + hap,
                    Toast.LENGTH_SHORT).show();
        }
    }
}

 

activity_main.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical">

    <EditText
        android:id="@+id/edtNum1"
        android:layout_width="match_parent"
        android:layout_height="wrap_content" />

    <EditText
        android:id="@+id/edtNum2"
        android:layout_width="match_parent"
        android:layout_height="wrap_content" />

    <RadioGroup
        android:id="@+id/rdoGroup"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content">

        <RadioButton
            android:id="@+id/rdoAdd"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:checked="true"
            android:text="더하기" />

        <RadioButton
            android:id="@+id/rdoSub"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="빼기" />

        <RadioButton
            android:id="@+id/rdoMul"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="곱하기" />

        <RadioButton
            android:id="@+id/rdoDiv"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="나누기" />
    </RadioGroup>

    <Button
        android:id="@+id/btnNewActivity"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="계산하기" />

</LinearLayout>

 

SecondActivity.java

package com.cookandroid.test;

import androidx.appcompat.app.AppCompatActivity;
import android.content.Intent;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;

public class SecondActivity extends AppCompatActivity {
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.second);
        setTitle("Second 액티비티");

        Intent inIntent = getIntent();
        String calc = (inIntent.getStringExtra("Calc"));

        int calValue = 0;
        if (calc.equals("+")) {
            calValue = inIntent.getIntExtra("Num1", 0) + inIntent.getIntExtra("Num2", 0);
        } else if (calc.equals("-")) {
            calValue = inIntent.getIntExtra("Num1", 0) - inIntent.getIntExtra("Num2", 0);
        } else if (calc.equals("*")) {
            calValue = inIntent.getIntExtra("Num1", 0) * inIntent.getIntExtra("Num2", 0);
        } else {
            calValue = inIntent.getIntExtra("Num1", 0) / inIntent.getIntExtra("Num2", 0);
        }

        final int retValue = calValue;

        Button btnReturn = findViewById(R.id.btnReturn);
        btnReturn.setOnClickListener(new View.OnClickListener() {
            public void onClick(View v) {
                Intent outIntent = new Intent(getApplicationContext(), MainActivity.class);
                outIntent.putExtra("Hap", retValue);
                setResult(RESULT_OK, outIntent);
                finish();
            }
        });
    }
}

 

second.xml

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical" >

    <Button
        android:id="@+id/btnReturn"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="돌아가기" />

</LinearLayout>

 

결과