[안드로이드프로그래밍6판] 명시적 인텐트, 양방향 액티비티

1. 양방향 액티비티

1) 형태

<메인> - 초기 데이터 전달, 다시 받는 곳

 a. 데이터 전달

Intent intent = new Intent(MainActivity.this, SecondActivity.class);
intent.putExtra("first", Integer.parseInt(etName1.getText().toString()));
intent.putExtra("second", Integer.parseInt(etName2.getText().toString()));
startActivityForResult(intent, 0);

 b. 다시 받을 때 (onCreate 외부에 메서드 선언 필요)

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

 

<세컨드> - 초기 데이터 받고, 정정해서 다시 전달하는 곳

 a. 초기 데이터 받음

Intent intent = getIntent();
int hapValue = intent.getIntExtra("first", 0) + intent.getIntExtra("second", 0);

 b. 메인으로 재 전달 - btn 메서드 안 코드들임.

Intent outIntent = new Intent(getApplicationContext(), MainActivity.class);
outIntent.putExtra("Hap", hapValue);
setResult(RESULT_OK, outIntent);
finish();

 

 

2. 예제

 

실행 화면

메인	세컨드	메인

 

<MainActivity.java>

package com.cookandroid.practice10_2;

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.Toast;

public class MainActivity extends AppCompatActivity {

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

        Button btnSubmit = findViewById(R.id.submit);
        EditText etName1 = findViewById(R.id.etName1);
        EditText etName2 = findViewById(R.id.etName2);
        btnSubmit.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                Intent intent = new Intent(MainActivity.this, SecondActivity.class);
                intent.putExtra("first", Integer.parseInt(etName1.getText().toString()));
                intent.putExtra("second", Integer.parseInt(etName2.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);
            Toast.makeText(getApplicationContext(), "합계 : " + hap, Toast.LENGTH_SHORT).show();
        }
    }
}

 

 

<SecondActivity.java>

package com.cookandroid.practice10_2;

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

import androidx.annotation.Nullable;

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

        Intent intent = getIntent();
        int hapValue = intent.getIntExtra("first", 0)
                + intent.getIntExtra("second", 0);
        Button btnBack = findViewById(R.id.back);
        btnBack.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                Intent outIntent = new Intent(getApplicationContext(), MainActivity.class);
                outIntent.putExtra("Hap", hapValue);
                setResult(RESULT_OK, outIntent);
                finish();
            }
        });

    }
}