显示前一个片段

Question

如何删除当前并显示前一个片段？就像如果我按“返回”按钮

我使用这样的结构：

FragmentManager fm=getFragmentManager(); 
FragmentTransaction ft=fm.beginTransaction(); 
ft.remove(fragment).commit(); 

但它只是删除当前片段，没有表现出以往

Answer 1

你必须调用FragmentTransaction.addToBackStack(null)在其中添加该片段，然后在您想要删除它时调用FragmentManager.popBackStack()。

Answer 2

在您的活动添加这个方法：

@Override 
    public boolean onKeyDown(int keyCode, KeyEvent event) { 
     if (keyCode == KeyEvent.KEYCODE_BACK && event.getRepeatCount() == 0) { 
      if(this.getFragmentManager().getBackStackEntryCount() != 0){ 
       this.getFragmentManager().popBackStack(); 
       return true; 
      } 
      // If there are no fragments on stack perform the original back button event 
     } 

     return super.onKeyDown(keyCode, event); 
    } 

然后你在哪里改变片段做到这一点：

FragmentTransaction transaction = getFragmentManager().beginTransaction(); 
transaction.replace(android.R.id.content, new YourFragmentName()); 
transaction.addToBackStack(null); // this is needed for the above code to work 
transaction.commit(); 

Answer 3

尽量表现之后删除以前的片段：

FragmentManager fm=getSupportFragmentManager(); 
    FragmentTransaction ft=fm.beginTransaction(); 
    ft.remove(fragment).commit(); 

    previousFragment=(SherlockFragment)getSupportFragmentManager() 
    .findFragmentByTag(""+currentTagNum); 
    getSupportFragmentManager().beginTransaction() 
      .show(mFragment) 
      .commit();