[안드로이드 스튜디오] 양방향 액티비티

양방향 액티비티와 데이터 전달

• 메인 액티비티에서 세컨드 액티비티로 데이터를 넘긴 후에 다시 세컨드 액티비티에서 메인 액티비티로 데이터를 돌려주는 경우도 있음

---

양방향 데이터 전달 예제

• 메인 액티비티의 에디트텍스트의 두 수를 세컨드 액티비티에서 더한 후에 다시 메인 액티비티로 돌려줌

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"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".MainActivity"
    android:orientation="vertical">

    <EditText
        android:id="@+id/edtNum1"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:ems="10"
        android:inputType="number"
        android:text=""
        tools:layout_editor_absoluteX="4dp"
        tools:layout_editor_absoluteY="23dp" />

    <EditText
        android:id="@+id/edtNum2"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:ems="10"
        android:inputType="number"
        android:text=""
        tools:layout_editor_absoluteX="10dp"
        tools:layout_editor_absoluteY="95dp" />

    <Button
        android:id="@+id/btnNewActivity"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="더하기"
        tools:layout_editor_absoluteX="44dp"
        tools:layout_editor_absoluteY="172dp" />
</LinearLayout>

MainActivity.java

package com.example.a10_17;

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

import androidx.appcompat.app.AppCompatActivity;

public class MainActivity extends AppCompatActivity {
    EditText edtNum1;
    EditText edtNum2;
    Button btnNewActivity;

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

        btnNewActivity = (Button) findViewById(R.id.btnNewActivity);
        edtNum1 = (EditText) findViewById(R.id.edtNum1);
        edtNum2 = (EditText) findViewById(R.id.edtNum2);
        btnNewActivity.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                Intent intent = new Intent(getApplicationContext(), secondActivity.class);
                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) {
        super.onActivityResult(requestCode, resultCode, data);
        if (resultCode == RESULT_OK) {
            int hap = data.getIntExtra("HAP", 0); // 이거 변수가 틀린거였음
            Toast.makeText(getApplicationContext(), "합계 : " + hap, Toast.LENGTH_SHORT).show();
        }
    }

}

second.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:layout_width="match_parent"
    android:layout_height="match_parent">

    <Button
        android:id="@+id/btnReturn"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="돌아가기"
        tools:layout_editor_absoluteX="129dp"
        tools:layout_editor_absoluteY="31dp" />
</LinearLayout>

secondActivtiy.java

package com.example.a10_17;

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

import androidx.appcompat.app.AppCompatActivity;

public class secondActivity extends AppCompatActivity {
    Button btnReturn;

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

        Intent inIntent = getIntent();
        final int hapValue = inIntent.getIntExtra("NUM1", 0) + inIntent.getIntExtra("NUM2", 0);

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

    }

}

AndroidManifest.xml

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

    <application
        android:allowBackup="true"
        android:dataExtractionRules="@xml/data_extraction_rules"
        android:fullBackupContent="@xml/backup_rules"
        android:icon="@mipmap/ic_launcher"
        android:label="@string/app_name"
        android:roundIcon="@mipmap/ic_launcher_round"
        android:supportsRtl="true"
        android:theme="@style/Theme._10_17"
        tools:targetApi="31">
        <activity
            android:name=".MainActivity"
            android:exported="true">
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />

                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>
        <activity android:name=".secondActivity" android:label="secondActivity">
        </activity>
    </application>

</manifest>