startActivityForResult

MainActivity整個代碼

package com.example.day05_activityresult;

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


public class MainActivity extends Activity {

    private Button btc;
    private Button btn;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        init();
    }
    public void init(){
        btc=(Button)findViewById(R.id.btc);
        btn=(Button)findViewById(R.id.btn);
    }
   public void citychoose(View v){
        Intent intent=new Intent(MainActivity.this, CityActivity.class);
        startActivityForResult(intent, 1);//參數一:Intent(要跳轉的)  參數二:請求碼
    }
    public void nationchoose(View v){
        Intent intent=new Intent(MainActivity.this, NationActivity.class);
        startActivityForResult(intent, 2);
    }
    @Override//參數一:請求碼(區分是哪個activity返回的結果) ;參數二:結果碼;參數三:返回的結果值
    protected void onActivityResult(int requestCode, int resultCode, Intent data) {
        if(requestCode==1){
             btc.setText(data.getStringExtra("city"));
        }
        if(requestCode==2){
         btn.setText(data.getStringExtra("nation"));
    }
        super.onActivityResult(requestCode, resultCode, data);
    }

}

CityActivity的代碼

 package com.example.day05_activityresult;

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

public class CityActivity extends Activity {

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

    public void pess(View v){
        Intent intent=getIntent();//getIntent()
        switch (v.getId()) {
        case R.id.bj:
            intent.putExtra("city", "北京");
            break;
        case R.id.sh:
            intent.putExtra("city", "上海");
            break;
        case R.id.gz:
            intent.putExtra("city", "廣州");
            break;
        default:
            break;
        }
        setResult(RESULT_OK, intent);//參數一:結果碼,參數二:Intent
        finish();//關閉當前Activity
    }

}