锁定和解锁屏幕后恢复片段

Question

我有 3(A,B,C) 片段和一个 activity.fragment A 添加到 activity 然后片段 B,C replaced.now 片段 A 替换为片段 B.in 片段 B 我添加了一些细节。然后我在解锁屏幕后锁定屏幕 ..它是打开的 activity 片段 A（已添加）。如何在锁定和解锁屏幕后恢复片段 B

Answer 1

你应该保存扩展 Application class 的 class 中的状态，因为 activity 将在显示更改后释放（发生锁定屏幕，或方向更改） .

您的新申请 class：

public class myApp extends Application {
   public int state; //field that keeps saved state

你的 activity class:

//add this method to save changed state
//then call it every time you change the fragment index
private void onChangeFragment(int stateid) {
    myApp sapp = (myApp) this.getApplication(); 
    sapp.state = stateid;
}

@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);                            

    myApp sapp = (myApp) this.getApplication();              
    //restore fragment from sapp.state value
    switch (sapp.state) {
        case 0 : //fragment A
            {  setContentView(R.layout.fragmentA);
               //maybe Fragment newFragment = new MyFragmentA(); ... and so on
               break;  
            }
        case 1 : //fragment B
            {  setContentView(R.layout.fragmentB);
               //maybe Fragment newFragment = new MyFragmentB(); ... and so on
               break;  
            }
    }

并在清单中 <application android:icon="@drawable/icon" android:label="@string/app_name" ...android:name=".myApp"`>

其他方法是使用activity之前通过Bundle savedInstanceState保存的状态。

你的 activity class:

private int state; //field that keeps saved state

@Override
public void onRestoreInstanceState(Bundle savedInstanceState) {
    state = savedInstanceState.getInteger(FRAGMENT_STATE_KEY);
    //restore the fragment from state value here
    //switch (state) {....
    //....
}

// invoked when the activity may be temporarily destroyed, save the instance state here
@Override
public void onSaveInstanceState(Bundle outState) {
    out.putInteger(FRAGMENT_STATE_KEY, state);

    // call superclass to save any view hierarchy
    super.onSaveInstanceState(out);

锁定和解锁屏幕后恢复片段

Restore fragment after lock and unlock screen

android

android-service