Android_Java(20) - MyIntent(3)

1. 명시적 인텐트 
    1) 다른 액티비티의 이름을 명확히 지정할 때 사용하는 방법 
    2) 명시적 인텐트와 데이터의 전달
        - 메인 액티비티에서 인텐트에 데이터를 실어서 넘긴 후, 세컨드 액티비티에서 받은 데이터 처리하는 방식(한쪽 방향)
        - 양방향 액티비티의 데이터 전달 
            - 서브 액티비티 시작 : startActivityForResult()
            - 액티비티에서 결과 받기 : onActivityResult()
        - 값을 저장하고, 값을 읽는 메서드
            - putExtra()
            - getIntExtra()
              getStringExtra().. 

 

[양방향성 명시적 인텐트]

 

<ResultActivity>

<?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="fill_parent"
    android:layout_height="fill_parent"
    android:orientation="vertical"
    tools:context=".MainActivity">

    <EditText
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:id="@+id/edtNum1">
    </EditText>
    <EditText
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:id="@+id/edtNum2">
    </EditText>

    <RadioGroup
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:id="@+id/rdoGroup">
        <RadioButton
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:id="@+id/radAdd"
            android:checked="true"
            android:text="더하기"/>
        <RadioButton
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:id="@+id/radSub"
            android:text="빼기"/>
        <RadioButton
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:id="@+id/radMul"
            android:text="곱하기"/>
        <RadioButton
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:id="@+id/radDiv"
            android:text="나누기"/>
    </RadioGroup>

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

package kr.co.myintent2;

import androidx.annotation.Nullable;
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
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        getSupportActionBar().setDisplayShowHomeEnabled(true);
        getSupportActionBar().setIcon(R.drawable.ic_launcher);
        setTitle("메인 액티비티");

        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() {
            //버튼을 클릭하면 SecondActivity를 시작함
            @Override
            public void onClick(View view) {
                //명시적 인텐트
                Intent intent = new Intent(getApplicationContext(), SecondActivity.class);
                switch (rdoGroup.getCheckedRadioButtonId()){
                    case R.id.radAdd:
                        intent.putExtra("Calc", "+");
                        break;
                    case R.id.radSub:
                        intent.putExtra("Calc", "-");
                        break;
                    case R.id.radMul:
                        intent.putExtra("Calc", "*");
                        break;
                    case R.id.radDiv:
                        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, @Nullable Intent data) {
        super.onActivityResult(requestCode, resultCode, data);

        if(resultCode == RESULT_OK){
            int answer = data.getIntExtra("answer", 0);
            Toast.makeText(getApplicationContext(), "결과 : " + answer, Toast.LENGTH_SHORT).show();
        }
    }
}

---

<SecondActivity>

<?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">

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

</LinearLayout>

package kr.co.myintent2;

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.activity_second);
        getSupportActionBar().setDisplayShowHomeEnabled(true);
        getSupportActionBar().setIcon(R.drawable.ic_launcher);
        setTitle("Second 액티비티");

        Intent intent = getIntent();
        String calc = intent.getStringExtra("Calc");
        int calValue = 0;

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

        final int retValue = calValue;
        Button btnReturn = findViewById(R.id.btnReturn);
        btnReturn.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                Intent outIntent = new Intent(getApplicationContext(), MainActivity.class);
                outIntent.putExtra("answer", retValue);
                setResult(RESULT_OK, outIntent);
                finish();
            }
        });

    }
}

---

[결과 출력]

01234567