[Android Studio] RegisterForActivityResult

activity_main.xml

<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout 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">

    <TextView
        android:id="@+id/tv_result"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Hello World!"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent" />

    <Button
        android:id="@+id/btn_move"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Button"
        app:layout_constraintEnd_toEndOf="@+id/tv_result"
        app:layout_constraintStart_toStartOf="@+id/tv_result"
        app:layout_constraintTop_toBottomOf="@+id/tv_result" />

</androidx.constraintlayout.widget.ConstraintLayout>

 

activity_sub.xml

<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout 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:id="@+id/e"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".SubActivity">

  <EditText
      android:id="@+id/et_input"
      android:layout_width="wrap_content"
      android:layout_height="wrap_content"
      android:ems="10"
      android:inputType="text"
      android:text="Name"
      app:layout_constraintBottom_toBottomOf="parent"
      app:layout_constraintEnd_toEndOf="parent"
      app:layout_constraintStart_toStartOf="parent"
      app:layout_constraintTop_toTopOf="parent" />

  <Button
      android:id="@+id/btn_back"
      android:layout_width="wrap_content"
      android:layout_height="wrap_content"
      android:layout_marginTop="32dp"
      android:text="Button"
      app:layout_constraintEnd_toEndOf="@+id/et_input"
      app:layout_constraintStart_toStartOf="@+id/et_input"
      app:layout_constraintTop_toBottomOf="@+id/et_input" />
</androidx.constraintlayout.widget.ConstraintLayout>

 

MainActivity.java

package com.example.registerforactivityresult;

import androidx.activity.result.ActivityResultLauncher;
import androidx.activity.result.contract.ActivityResultContracts;
import androidx.appcompat.app.AppCompatActivity;

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

public class MainActivity extends AppCompatActivity {

    TextView tv_result;

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

        tv_result = findViewById(R.id.tv_result);

        findViewById(R.id.btn_move).setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                Intent intent = new Intent(MainActivity.this, SubActivity.class);
                getSubActivityResult.launch(intent); // startActivityForResult 랑 동일한 기능 수행..!
            }
        });

    }

    private final ActivityResultLauncher<Intent> getSubActivityResult = registerForActivityResult(
            new ActivityResultContracts.StartActivityForResult(),
            result -> {
                // 서브 액티비티로부터 돌아올 때의 서브 액티비티에서 벌어지는 어떠한 결과 값을 받아 올 수 있는 통로..!
                if (result.getResultCode() == RESULT_OK) {
                    // 서브 액티비티의 입력 값을 메인에서 받아서 텍스트뷰에 표시...!
                    tv_result.setText(result.getData().getStringExtra("value")); //getStringExtra로 받아옴
                }
            }
    );

}

만약 버튼 별로 여러가지 기능을 만들고 싶다면

 

private final ActivityResultLauncher<Intent> getSubActivityResult = registerForActivityResult(
            new ActivityResultContracts.StartActivityForResult(),
            result -> {
                // 서브 액티비티로부터 돌아올 때의 서브 액티비티에서 벌어지는 어떠한 결과 값을 받아 올 수 있는 통로..!
                if (result.getResultCode() == RESULT_OK) {
                    // 서브 액티비티의 입력 값을 메인에서 받아서 텍스트뷰에 표시...!
                    tv_result.setText(result.getData().getStringExtra("value")); //getStringExtra로 받아옴
                }
            }
    );

}

 

여기서 getSubActivityResult와 같은 변수 명을 목적에 맞게 이름을 설정한 후, 구현하면 된다.

 

SubActivity.java

package com.example.registerforactivityresult;

import androidx.appcompat.app.AppCompatActivity;

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

public class SubActivity extends AppCompatActivity {

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

        EditText et_input = findViewById(R.id.et_input);
        findViewById(R.id.btn_back).setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                String strInputValue = et_input.getText().toString();

                // 메인 액티비티로 다시 돌아갈 때 입력필드의 입력 값을 되돌려 준다..!
                Intent intent = new Intent();
                intent.putExtra("value",strInputValue);
                setResult(RESULT_OK,intent);
                finish(); // 이 부분에서 SubActivity가 종료되고, MainActivity로 돌아갑니다.
            }
        });

    }
}

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결과