方法未定义类型对象

Question

I am using the tutorial from the link http://thinkandroid.wordpress.com/2010/01/24/handling-screen-off-and-screen-on-intents/ and try to get the screen on and off data in android phone. But I come up with the The method onpause is undefined for the type object , the same error happens in the OnResume method. I set the android level from 10-17.

Here is the whole code for that:

package com.example.myfirstapp;

import android.content.BroadcastReceiver;
import android.content.Intent;
import android.content.IntentFilter;

public class ExampleActivity {
    protected void onCreate() {
        // INITIALIZE RECEIVER
        IntentFilter filter = new IntentFilter(Intent.ACTION_SCREEN_ON);
        filter.addAction(Intent.ACTION_SCREEN_OFF);
        ScreenReceiver mReceiver = new ScreenReceiver();
        registerReceiver(mReceiver, filter);
        // YOUR CODE
    }

    private void registerReceiver(ScreenReceiver mReceiver, IntentFilter filter) {
        // TODO Auto-generated method stub

    }

    protected void onPause() {
        // WHEN THE SCREEN IS ABOUT TO TURN OFF
        if (ScreenReceiver.wasScreenOn) {
            // THIS IS THE CASE WHEN ONPAUSE() IS CALLED BY THE SYSTEM DUE TO A SCREEN STATE CHANGE
            System.out.println("SCREEN TURNED OFF");
        } else {
            // THIS IS WHEN ONPAUSE() IS CALLED WHEN THE SCREEN STATE HAS NOT CHANGED
        }
        super.onPause();
    }

    protected void onResume() {
        // ONLY WHEN SCREEN TURNS ON
        if (!ScreenReceiver.wasScreenOn) {
            // THIS IS WHEN ONRESUME() IS CALLED DUE TO A SCREEN STATE CHANGE
            System.out.println("SCREEN TURNED ON");
        } else {
            // THIS IS WHEN ONRESUME() IS CALLED WHEN THE SCREEN STATE HAS NOT CHANGED
        }
        super.onResume();
    }
}

Answer 1

First off,

public class ExampleActivity {
...

For any activities you define in Android, you must extend from the Activity class

public class ExampleActivity extends Activity {

OnCreate, OnResume and OnPause are override methods, so change them accordingly

@Override
protected void onCreate() {
...

@Override
protected void onPause() {
...

@Override
protected void onResume() {
...

Answer 2

The issues is that you have to extend Activity (check the article to confirm this), you also have to Override each of the inherited methods (using the @Override notation).

Also, you have to remove "registerReciever" as this call is inherited from (and handled by) the Activity.

I have posted what I believe is the correct coding.

package com.example.myfirstapp;

import android.content.BroadcastReceiver;
import android.content.Intent;
import android.content.IntentFilter;

public class ExampleActivity extends Activity {
@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    // INITIALIZE RECEIVER
    IntentFilter filter = new IntentFilter(Intent.ACTION_SCREEN_ON);
    filter.addAction(Intent.ACTION_SCREEN_OFF);
    ScreenReceiver mReceiver = new ScreenReceiver();
    registerReceiver(mReceiver, filter);
    // YOUR CODE
}


@Override
protected void onPause() {
    // WHEN THE SCREEN IS ABOUT TO TURN OFF
    if (ScreenReceiver.wasScreenOn) {
        // THIS IS THE CASE WHEN ONPAUSE() IS CALLED BY THE SYSTEM DUE TO A SCREEN STATE CHANGE
        System.out.println("SCREEN TURNED OFF");
    } else {
        // THIS IS WHEN ONPAUSE() IS CALLED WHEN THE SCREEN STATE HAS NOT CHANGED
    }
    super.onPause();
}

@Override
protected void onResume() {
    // ONLY WHEN SCREEN TURNS ON
    if (!ScreenReceiver.wasScreenOn) {
        // THIS IS WHEN ONRESUME() IS CALLED DUE TO A SCREEN STATE CHANGE
        System.out.println("SCREEN TURNED ON");
    } else {
        // THIS IS WHEN ONRESUME() IS CALLED WHEN THE SCREEN STATE HAS NOT CHANGED
    }
    super.onResume();
}
}