How Android callback Activity in Service, BroadCast, Application in

1. Define Interface

public interface NetEvevt {
    public void onNetChange(int netMobile);
}

2. Implement a callback interface

public class MainActivity extends AppCompatActivity implements NetEvevt{
    // 定义静态变量
    public static NetEvevt evevt;
    CustomerReceiver customerReceiver=null;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        // 赋值给变量
        evevt=this;
        if(customerReceiver==null){
            customerReceiver=new CustomerReceiver();
            IntentFilter filter = new IntentFilter("com.denganzhi.greendao.CustomerReceiver.action");
            registerReceiver(customerReceiver, filter);
        }
    }
    // 实现接口,重写方法
    @Override
    public void onNetChange(int netMobile) {
        Toast.makeText(MainActivity.this,"netMobile:"+netMobile,Toast.LENGTH_SHORT).show();
    }

    public void methodClick(View view){
        Intent intent = new Intent("com.denganzhi.greendao.CustomerReceiver.action");
        sendBroadcast(intent);
    }

    @Override
    protected void onDestroy() {
        super.onDestroy();

        if(customerReceiver!=null){
            unregisterReceiver(customerReceiver);
            customerReceiver=null;
        }
    }
}

3. broadcast transmission

CustomerReceiver the extends the BroadcastReceiver {class public 

    public NetEvevt evevt = MainActivity.evevt; 


    @Override 
    public void the onReceive (the Context context, the Intent Intent) { 
        // the TODO: This Method The IS Called When Receiving the BroadcastReceiver IS 
        // Broadcast AN the Intent. 
   // Toast. makeText (context, "receive", Toast.LENGTH_LONG) the .Show (); 
        // get a class implementation method, a method invocation 
        IF (evevt = null!) { 
            evevt.onNetChange (110); 
        } 

    } 

    // custom interface 
public interface NetEvevt {// 
// public void onNetChange (int netMobile); 
//} 

}