我编写了一个代码，我尝试在片段1,2,3,4之间导航。导航类似于：1-> 2-> 3-> 4-> 2.
每个片段都有一个按钮，其onClickListener调用接口中的方法，该方法由mainactivity实现，其中position作为参数传递。
e.g。 onClick第4个片段中的按钮调用方法，其中我将位置参数传递为'2'以调用第二个片段。
现在，我已将事务1-＆gt; 2添加到backstack，使用backstack名称“second”。当我尝试从4> 2时，我使用函数popBackStackImmediate（“second”，0）。但是，布尔响应为false，并且不会从堆栈中弹出任何内容。
我的问题是：
我的代码中的MainActivity是：
`
public class MainActivity extends AppCompatActivity implements Frag1.OnFragmentInteractionListener, Frag2.OnFragmentInteractionListener, Frag3.OnFragmentInteractionListener, Frag4.OnFragmentInteractionListener {
LinearLayout layout;
Frag1 frag1;
Frag2 frag2;
Frag3 frag3;
Frag4 frag4;
android.support.v4.app.FragmentTransaction transaction;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
Log.i("I", "Main Act");
layout = (LinearLayout) findViewById(R.id.frag);
frag1 = Frag1.newInstance();
transaction = getSupportFragmentManager().beginTransaction();
// Replace whatever is in the fragment_container view with this fragment,
// and add the transaction to the back stack so the user can navigate back
transaction.add(R.id.frag, frag1, "first");
// frag1 = Frag1.newInstance();
// transaction.add(R.id.frag, frag1, "first1");
// transaction.add(R.id.frag, frag2, "second");
// transaction.add(R.id.frag, frag2, "second");
// transaction.add(R.id.frag, frag3, "third");
// Commit the transaction
// transaction.add(R.id.frag, frag3, "third");
// transaction.replace(R.id.frag, frag2, "second");
transaction.commit();
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.menu_main, menu);
return true;
}
@Override
public boolean onOptionsItemSelected(MenuItem item) {
// Handle action bar item clicks here. The action bar will
// automatically handle clicks on the Home/Up button, so long
// as you specify a parent activity in AndroidManifest.xml.
int id = item.getItemId();
//noinspection SimplifiableIfStatement
if (id == R.id.action_settings) {
return true;
}
return super.onOptionsItemSelected(item);
}
//片段到活动界面实现
@Override
public void onFragmentInteraction(int pos) {
if (pos == 2) {
// Fragment f = getSupportFragmentManager().findFragmentByTag("second");
FragmentManager manager = getSupportFragmentManager();
boolean isAvail = manager.popBackStackImmediate("second", 0);
if (isAvail) {
// frag2 = (Frag2) f;
Log.i("MainAct", "Instance of 2 yes");
}else{
transaction = getSupportFragmentManager().beginTransaction();
frag2 = Frag2.newInstance();
Log.i("MainAct", "Instance of 2 No");
transaction.replace(R.id.frag, frag2, "second");
transaction.addToBackStack("second");
transaction.commit();
}
} else if (pos == 3) {
Fragment f = getSupportFragmentManager().findFragmentByTag("third");
transaction = getSupportFragmentManager().beginTransaction();
if (f instanceof Frag3) {
frag3 = (Frag3) f;
Log.i("MainAct", "Instance of 3 yes");
}else{
frag3 = Frag3.newInstance();
Log.i("MainAct", "Instance of 3 No");
}
transaction.replace(R.id.frag, frag3, "third");
transaction.commit();
}
else if (pos == 4) {
Fragment f = getSupportFragmentManager().findFragmentByTag("four");
transaction = getSupportFragmentManager().beginTransaction();
if (f instanceof Frag3) {
frag4 = (Frag4) f;
Log.i("MainAct", "Instance of 4 yes");
}else{
frag4 = Frag4.newInstance();
Log.i("MainAct", "Instance of 4 No");
}
transaction.replace(R.id.frag, frag4, "four");
transaction.commit();
}
}
}`
答案 0 :(得分：0)
您正试图致电public interface PageTraveller {
public void openPage(int pageNo);
}
而是替换片段。
试试这个，
创建界面PageTraveller并在MainActivity中实现
@Override
public void openPage(int pageNo) {
android.support.v4.app.Fragment fragment;
switch (pageNo){
case 1:
fragment = getSupportFragmentManager().findFragmentByTag("fragmentOne");
fragmentManager.beginTransaction().replace(R.id.pageContainer,fragment).addToBackStack("fragmentOne").commit();
break;
case 2:
fragment = getSupportFragmentManager().findFragmentByTag("fragmentTwo");
if (fragment instanceof FragmentTwo)
fragmentTwo = (FragmentTwo)fragment;
else
fragmentTwo = new FragmentTwo();
fragmentManager.beginTransaction().replace(R.id.pageContainer,fragmentTwo).addToBackStack("fragmentTwo").commit();
break;
case 3:
fragment = getSupportFragmentManager().findFragmentByTag("fragmentThree");
if (fragment instanceof FragmentTwo)
fragmentThree = (FragmentThree)fragment;
else
fragmentThree = new FragmentThree();
fragmentManager.beginTransaction().replace(R.id.pageContainer,fragmentThree).addToBackStack("fragmentThree").commit();
break;
case 4:
fragment = getSupportFragmentManager().findFragmentByTag("fragmentFour");
if (fragment instanceof FragmentTwo)
fragmentFour = (FragmentFour)fragment;
else
fragmentFour = new FragmentFour();
fragmentManager.beginTransaction().replace(R.id.pageContainer,fragmentFour).addToBackStack("fragmentFour").commit();
break;
}
}
覆盖方法openPage（）
public class FragmentOne extends Fragment{
PageTraveller pageTraveller;
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
View viewOne = inflater.inflate(R.layout.fragment_one,null);
Button btnOne = (Button)viewOne.findViewById(R.id.text1);
btnOne.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
pageTraveller.openPage(2);
}
});
return viewOne;
}
@Override
public void onAttach(Context context) {
super.onAttach(context);
pageTraveller = (PageTraveller) context;
}
}创建第一个片段FragmentOne
<Button
android:id="@+id/btnOne"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:textSize="40dp"
android:layout_gravity="center|center_horizontal|center_vertical"
android:text="Fragment 1"/>
在XML fragment_one add
中
FragmentFour
pageTraveller.openPage(2);来电while True:
for i in ["\\","-","|","\\","|"]:
print "%s\r" % i
如需更多参考，请尝试1. go back to the previous fragment in the backstack
它对我的工作，尝试它可能会帮助你。