Android从Java类回调到Activity [英] Android make callback to an Activity from java class

问题描述

如何通过Java类对Activity进行回调?

How can i make a callback to an Activity form a Java Class?

示例:

    public class TestClass{
    String text = "Test";
    public TestClass(Context context){
            startActivity(new Intent(context, SomeActivity.class));
    }

    private void sendToSomeActivity(){
      //Call some method of SomeActivity and pas text as string
    }

   }

当调用 sendToSomeActivity()时，我想对已经启动的 SomeActivity 进行回调，并将一些文本传递给Activity.在 SomeActivity 中，我要使用文本.

When sendToSomeActivity() is called, i want to make a callback to the already started SomeActivity and pass some text to the Activity. In SomeActivity i want to use the text.

注意:我要使用的TestClass对象已经在另一个类中创建.

Note: The TestClass object that i want to use is already created in another class.

这怎么办?

推荐答案

我选择的解决方案如下:

The solution I chose is as follows:

使用BroadcastReceivers在Java类和Activity之间进行通信.

Use BroadcastReceivers to communicate between Java classes and Activities.

示例:

public class SomeActivity extends Activity{
    private MyBroadcastReceiver receiver;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        receiver = new MyBroadcastReceiver();
        this.registerReceiver(receiver, new IntentFilter(MyBroadcastReceiver.ACTION));
    }

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

    private class MyBroadcastReceiver extends BroadcastReceiver{
        public static final String ACTION = "com.example.ACTION_SOMETHING"
        @Override
        public void onReceive(Context context, Intent intent) {
            String test = intent.getStringExtra("dataToPass");
        }
    }
} 

public class TestClass{
    private String test = "TEST";
    private Context context;

    public TestClass(Context context){
      this.context = context;
    }
    private void sendToSomeActivity(){
       Intent intent = new Intent();
       intent.setAction(SomeActivity.MyBroadcastReceiver.ACTION);
       intent.putExtra("dataToPass", test);
       context.sendBroadcast(intent); 
    }

}

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