android_11 activityA调activityB，又返回activityA

ButtonDemoActivity(activityA)

在之前代码的基础上加这个

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case R.id.btn_to_sec_return:				intent = new Intent();				intent.setClass(getApplicationContext(), ButtonDemoActivity2.class);				intent.putExtra("back", "我是传递返回button的参数");				startActivityForResult(intent, REQUEST_CODE);				break;

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activityA接收返回，需要重写：

//传递返回所需要的方法	@Override	protected void onActivityResult(int requestCode, int resultCode, Intent data) {		if(requestCode == REQUEST_CODE && resultCode == ButtonDemoActivity2.RESULT_CODE) {			Toast t = Toast.makeText(getApplicationContext(), data.getStringExtra("back"), Toast.LENGTH_SHORT);			t.show();		}	}

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ButtonDemoActivity2(activityB)

package com.mhm.button.activity;import android.app.Activity;import android.content.Intent;import android.os.Bundle;import android.view.View;import android.view.View.OnClickListener;import android.widget.Button;import android.widget.TextView;import android.widget.Toast;public class ButtonDemoActivity2 extends Activity {	private TextView tv;		private Button btn_save_2;		private Button btn_back;		private String str;		public static final int RESULT_CODE = 1;		@Override	protected void onCreate(Bundle savedInstanceState) {		super.onCreate(savedInstanceState);		setContentView(R.layout.main2);		//接收到activityA传递过来的参数		Intent intent = getIntent();		Bundle b = intent.getExtras();		str = b.getString("str");		tv = (TextView)findViewById(R.id.tv_sec);		tv.setText(str);		btn_save_2 = (Button)findViewById(R.id.save_sec);		btn_save_2.setOnClickListener(listener);				btn_back = (Button)findViewById(R.id.btn_back);		btn_back.setOnClickListener(listener);			}		private OnClickListener listener = new OnClickListener() {		public void onClick(View v) {			Button b = (Button)v;			switch (b.getId()) {			case R.id.save_sec:				Toast t = Toast.makeText(getApplicationContext(), str, Toast.LENGTH_SHORT);				t.show();				break;							case R.id.btn_back:				Intent intent = new Intent();				System.out.println("back");				intent.putExtra("back", "我是从B返回到A的值");				setResult(RESULT_CODE, intent);				//结束此activity，返回到activityA				finish();				break;			default:				break;			}		}	};	}

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