Activity 간 전달

1. AndroidManifest.xml

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

    <application
        android:allowBackup="true"
        android:icon="@mipmap/ic_launcher"
        android:label="@string/app_name"
        android:roundIcon="@mipmap/ic_launcher_round"
        android:supportsRtl="true"
        android:theme="@style/AppTheme">
        <activity android:name=".SecondActivity"></activity>
        <activity android:name=".MainActivity">
            <intent-filter> 
                <action android:name="android.intent.action.MAIN" /><!-- 액티비티 사작점인을 뜻하는 메인 액티비티-->

                <category android:name="android.intent.category.LAUNCHER" /><!-- 런처(launcher,휴대폰 홈화면)에서 실행 될수 잇는 액티비티임을 정의-->
            </intent-filter>
        </activity>
    </application>

</manifest>

 

2. 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:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:hint="이름"
        android:id="@+id/name_edit"/>
    <EditText
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:hint="나이"
        android:id="@+id/age_edit"/>
    <Button
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:hint="전송"
        android:id="@+id/submit_edit"/>

</LinearLayout>

3. activity_second.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"
    android:orientation="vertical"
    tools:context=".SecondActivity">
    <!--tools:text="데이터" 프리뷰에서만 보이는 값-->
    <TextView
        tools:text="데이터"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:id="@+id/message_edit_text"/>
    <Button
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:id="@+id/result_button"
        android:text="결과전달"/>
</LinearLayout>

4. MainActivity.java

package com.example.activityexam;

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

import androidx.annotation.Nullable;
import androidx.appcompat.app.AppCompatActivity;

public class MainActivity extends AppCompatActivity implements View.OnClickListener {

    public static final int REQUEST_CODE = 1000;
    private EditText mNameEditText;
    private  EditText mAgeEditText;


    //OnCreate() 메서드는 액티비티가 생성될 때 호출되는 콜백 메서드(내가 메서드를 실행하지 않아도 어떤 순간에 스스로 호출됨)
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main); //레이아웃 구성(표시)
        //레이아웃에서 입려된 이름과 나이
        mNameEditText=findViewById(R.id.name_edit);
        mAgeEditText=findViewById(R.id.age_edit);
        //버튼 이벤
        findViewById(R.id.submit_edit).setOnClickListener(this);
    }

    @Override
    public void onClick(View view) {
        //SecondActivity로 전환하는 Intent / 여기서 this는 MainActivity 자신을 가르킴
        Intent intent=new Intent(this,SecondActivity.class);
        // 이름, 나이 Intent에 추가
        intent.putExtra("name",mNameEditText.getText().toString());
        intent.putExtra("age",mAgeEditText.getText().toString());

        //startActivity(intent);
        //Intent의 정보로 토대로 다른 Activity를 시작
        startActivityForResult(intent,REQUEST_CODE);
    }

    //SecondActivity에서 돌려받은 결과 처
    @Override
    protected void onActivityResult(int requestCode, int resultCode, @Nullable Intent data) {
        super.onActivityResult(requestCode, resultCode, data);
        // 실패했을 경우 RESULT_CANCEL
        if(requestCode == REQUEST_CODE && resultCode==RESULT_OK && data !=null){
            //약속된 키값 result로 결과를 받음
            String result = data.getStringExtra("result");
            Toast.makeText(this,result,Toast.LENGTH_SHORT).show();
        }
    }
}

5. SecondActivity.java

package com.example.activityexam;

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

import androidx.appcompat.app.AppCompatActivity;

public class SecondActivity extends AppCompatActivity implements View.OnClickListener {
    private TextView mMessageTextView;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_second);
        //넘어온 값을 표시
        Intent intent=getIntent();
        String name=intent.getStringExtra("name");
        String age=intent.getStringExtra("age");

        mMessageTextView = findViewById(R.id.message_edit_text);
        mMessageTextView.setText(age+"살 "+name);

        findViewById(R.id.result_button).setOnClickListener(this);

    }

    @Override
    public void onClick(View view) {
        Intent intent=new Intent();
        intent.putExtra("result",mMessageTextView.getText().toString());
        //RESULT_OK, RESULT_CANCEL AppCompatActivity에 상수로 정의 
        setResult(RESULT_OK,intent);
        finish();
    }
}