发送通知，需要先新建一个通知的类：
public class MyReceiver extends BroadcastReceiver {

@Override
public void onReceive(Context context, Intent intent) {


    System.out.println("接收到了消息,消息的内容是："+intent.getStringExtra("data"));
}

}
之后使用sendBroadcast发送：
public class MainActivity extends AppCompatActivity implements View.OnClickListener {

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


    findViewById(R.id.btnSendMsg).setOnClickListener(this);
}

@Override
public void onClick(View v) {
    switch (v.getId()){
        case R.id.btnSendMsg:
            Intent i = new Intent(this,MyReceiver.class);
            i.putExtra("data","jikexueyuan");

            sendBroadcast(i);
            break;
    }
}

}