我的活动中有一些碎片
[1], [2], [3], [4], [5], [6]
如果当前活动片段是[2],那么在返回按钮上按下我必须从[2]返回到[1],否则什么也不做。
最好的做法是什么?
编辑:应用程序不能从[3]…[6]返回[2]
我的活动中有一些碎片
[1], [2], [3], [4], [5], [6]
如果当前活动片段是[2],那么在返回按钮上按下我必须从[2]返回到[1],否则什么也不做。
最好的做法是什么?
编辑:应用程序不能从[3]…[6]返回[2]
当前回答
对于那些谁使用静态片段
在这种情况下,如果你有一个静态片段,那么它会更可取。 为片段创建一个实例对象
private static MyFragment instance=null;
在MyFragment的onCreate()中初始化该实例
instance=this;
也可以创建一个函数来获取Instance
public static MyFragment getInstance(){
return instance;
}
也可以创建函数
public boolean allowBackPressed(){
if(allowBack==true){
return true;
}
return false;
}
//allowBack is a boolean variable that will be set to true at the action
//where you want that your backButton should not close activity. In my case I open
//Navigation Drawer then I set it to true. so when I press backbutton my
//drawer should be get closed
public void performSomeAction(){
//.. Your code
///Here I have closed my drawer
}
在你能做的活动中
@Override
public void onBackPressed() {
if (MyFragment.getInstance().allowBackPressed()) {
MyFragment.getInstance().performSomeAction();
}
else{
super.onBackPressed();
}
}
其他回答
当你在Fragments之间转换时,调用addToBackStack()作为FragmentTransaction的一部分:
FragmentTransaction tx = fragmentManager.beginTransation();
tx.replace( R.id.fragment, new MyFragment() ).addToBackStack( "tag" ).commit();
如果你需要更详细的控制(例如,当一些片段可见时,你想要抑制返回键),你可以在你的片段的父视图上设置一个OnKeyListener:
//You need to add the following line for this solution to work; thanks skayred
fragment.getView().setFocusableInTouchMode(true);
fragment.getView().requestFocus();
fragment.getView().setOnKeyListener( new OnKeyListener()
{
@Override
public boolean onKey( View v, int keyCode, KeyEvent event )
{
if( keyCode == KeyEvent.KEYCODE_BACK )
{
return true;
}
return false;
}
} );
rootView.setFocusableInTouchMode(true);
rootView.requestFocus();
rootView.setOnKeyListener(new View.OnKeyListener() {
@Override
public boolean onKey(View v, int keyCode, KeyEvent event) {
if (keyCode == KeyEvent.KEYCODE_BACK) {
Fragment NameofFragment = new NameofFragment;
FragmentTransaction transaction=getFragmentManager().beginTransaction();
transaction.replace(R.id.frame_container,NameofFragment);
transaction.commit();
return true;
}
return false;
}
});
return rootView;
我宁愿这样做:
private final static String TAG_FRAGMENT = "TAG_FRAGMENT";
private void showFragment() {
final Myfragment fragment = new MyFragment();
final FragmentTransaction transaction = getSupportFragmentManager().beginTransaction();
transaction.replace(R.id.fragment, fragment, TAG_FRAGMENT);
transaction.addToBackStack(null);
transaction.commit();
}
@Override
public void onBackPressed() {
final Myfragment fragment = (Myfragment) getSupportFragmentManager().findFragmentByTag(TAG_FRAGMENT);
if (fragment.allowBackPressed()) { // and then you define a method allowBackPressed with the logic to allow back pressed or not
super.onBackPressed();
}
}
工作代码:
package com.example.keralapolice;
import android.app.Fragment;
import android.app.FragmentManager;
import android.app.FragmentManager.OnBackStackChangedListener;
import android.content.Intent;
import android.os.Bundle;
import android.util.Log;
import android.view.Gravity;
import android.view.KeyEvent;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.Toast;
public class ChiefFragment extends Fragment {
View view;
// public OnBackPressedListener onBackPressedListener;
@Override
public View onCreateView(LayoutInflater inflater,
ViewGroup container, Bundle args) {
view = inflater.inflate(R.layout.activity_chief, container, false);
getActivity().getActionBar().hide();
view.setFocusableInTouchMode(true);
view.requestFocus();
view.setOnKeyListener(new View.OnKeyListener() {
@Override
public boolean onKey(View v, int keyCode, KeyEvent event) {
Log.i(getTag(), "keyCode: " + keyCode);
if (keyCode == KeyEvent.KEYCODE_BACK) {
getActivity().getActionBar().show();
Log.i(getTag(), "onKey Back listener is working!!!");
getFragmentManager().popBackStack(null, FragmentManager.POP_BACK_STACK_INCLUSIVE);
// String cameback="CameBack";
Intent i = new Intent(getActivity(), home.class);
// i.putExtra("Comingback", cameback);
startActivity(i);
return true;
} else {
return false;
}
}
});
return view;
}
}
在您的活动中添加此代码
@Override
public void onBackPressed() {
if (getFragmentManager().getBackStackEntryCount() == 0) {
super.onBackPressed();
} else {
getFragmentManager().popBackStack();
}
}
并在commit()之前在Fragment中添加这一行
ft.addToBackStack(任何名称);