利用 BroadcastReceiver 在一个 Activity 当中显示结果

package com.android.broadcastmul;

import android.app.Activity;
import android.content.Intent;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.EditText;

public class MainActivity extends Activity {
	
	
	EditText edit1, edit2;
	
	@Override
	protected void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		setContentView(R.layout.activity_main);
		
		Button send = (Button)findViewById(R.id.send);
		edit1 = (EditText)findViewById(R.id.edit1);
		edit2 = (EditText)findViewById(R.id.edit2);
		
		send.setOnClickListener(new OnClickListener() {
			@Override
			public void onClick(View v) {
				
				Intent intent = new Intent(MainActivity.this, ActivityB.class);
				
				startActivity(intent);
				// UI 线程不安全，所以启动一个子线程
				new Thread(new Runnable() {
					
					@Override
					public void run() {
						
						Intent it = new Intent();
						it.setAction("com.android.broadcastmul");
						
						String str1 = edit1.getText().toString();
						String str2 = edit2.getText().toString();
						
						it.putExtra("first", str1);
						it.putExtra("second", str2);
						sendBroadcast(it);
						
						try {
							Thread.sleep(2000);
						} catch (InterruptedException e) {
							e.printStackTrace();
						}
					}
				}).start();
			}
		});
	}
	
}





package com.android.broadcastmul;

import android.app.Activity;
import android.content.BroadcastReceiver;
import android.content.Context;
import android.content.Intent;
import android.content.IntentFilter;
import android.os.Bundle;
import android.os.Handler;
import android.os.Message;
import android.util.Log;
import android.widget.EditText;
import android.widget.TextView;

public class ActivityB extends Activity {
	
	private Handler handler;
	TextView textView;
	MyReceiver receiver;
	
	@Override
	protected void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		setContentView(R.layout.activity_main2);
		// 动态注册，就不需要在 AndroidManifest.xml 中注册（四大组件都要注册）
		IntentFilter filter = new IntentFilter();
		filter.addAction("com.android.broadcastmul");
		receiver = new MyReceiver();
		registerReceiver(receiver, filter);
		
		textView = (TextView)findViewById(R.id.textView);
		
		handler = new Handler(){
			@Override
			public void handleMessage(Message msg) {
				if (msg.what == 0x123){
					textView.setText(msg.obj + "");
				}
				
			}
			
		};
	}
	
	private class MyReceiver extends BroadcastReceiver{
		@Override
		public void onReceive(Context context, Intent intent) {
			
			String str1 = intent.getStringExtra("first");
			String str2 = intent.getStringExtra("second");
			
			int sum =subCount(str1, str2);
			
			Message msg = handler.obtainMessage();
			msg.what = 0x123;
			msg.obj = sum;
			handler.sendMessage(msg);
		}
		
	}
	
	private int subCount(String str1, String str2){
		int a1 = Integer.parseInt(str1);
		int a2 = Integer.parseInt(str2);
		int sum = a1 + a2;

		return sum;
	}

	@Override
	protected void onDestroy() {
		super.onDestroy();
		unregisterReceiver(receiver);
	}
	
}