Question

比方说，如果我希望CountDownTimer在完成后更新一些UI元素，但在倒计时中间有一个配置更改，强制重新创建活动。

public class MyActivity extends Activity {

    private TextView textView;

    ....

    public void onButtonClicked(View view)
    {
        // start CountDownTimer
        new CountDownTimer(10000, 10000) {
            public void onTick(long millisUntilFinished) {
                // do nothing
            }
            public void onFinish() {
                textView.setText("Hello World!");
            }
        }.start();
    }

}

我发现当CountDownTimer完成时，它会在刚被销毁的活动中设置textView，但不会重新创建一个

Answer 1

http://developer.android.com/guide/topics/resources/runtime-changes.html

@Override
public void onSaveInstanceState(Bundle savedInstanceState) {
super.onSaveInstanceState(savedInstanceState);
// Save UI state changes to the savedInstanceState.
// This bundle will be passed to onCreate if the process is
// killed and restarted.
savedInstanceState.putString("timer",1223);

// etc.
}

@Override
public void onRestoreInstanceState(Bundle savedInstanceState) {
super.onRestoreInstanceState(savedInstanceState);
// Restore UI state from the savedInstanceState.
// This bundle has also been passed to onCreate.
 time = savedInstanceState.getString("time");
}

当您拥有大量数据时，例如来自数据库或arraylist的数据。

@Override 
public Object onRetainNonConfigurationInstance() {
final MyDataObject data = collectMyLoadedData(); 
return data;
}

在onCreate

 final MyDataObject data = (MyDataObject) getLastNonConfigurationInstance();
if (data == null) {
    data = loadMyData();
}

Answer 2

如果您的计数在文件中完成或未完成，您可以存储

http://developer.android.com/guide/topics/data/data-storage.html

并在

之后引用此文件

Answer 3

我已经实现了一个可调用的CountDownTimer，并在调用onPause（）/ onResume（）时暂停/恢复它，并使用setRetainInstance（true）在片段中引用它。它现在可以在屏幕旋转或任何配置更改后保持其进度。

如何创建在配置更改后保留的CountDownTimer

3 个答案: