据我所知，我一直按照 Facebook android 教程进行登录身份验证。但是，我遇到了问题。当我有 elogge din 时，我的“您现在已登录”片段永远不会显示。我相信这与 showFragment 方法有关。请在下面找到它：
private void showFragment(int fragmentIndex, boolean addToBackStack) {
FragmentManager fm = getSupportFragmentManager();
FragmentTransaction transaction = fm.beginTransaction();
for (int i = 0; i < fragments.length; i++) {
if (i == fragmentIndex) {
transaction.show(fragments[i]);
} else {
transaction.hide(fragments[i]);
}
}
if (addToBackStack) {
transaction.addToBackStack(null);
}
transaction.commit();
}
将 sys.out 放入其中时，fragmentIndex 也是 0，因此永远不会显示我的 else 片段。我有什么明显的遗漏吗？任何帮助将不胜感激。
请找到课程的其余部分和 XML 以防万一：
package com.example.social;
import android.content.Intent;
import android.os.Bundle;
import android.support.v4.app.Fragment;
import android.support.v4.app.FragmentActivity;
import android.support.v4.app.FragmentManager;
import android.support.v4.app.FragmentTransaction;
import android.view.Menu;
import android.view.MenuItem;
import com.facebook.Session;
import com.facebook.SessionState;
import com.facebook.UiLifecycleHelper;
public class DashBoard extends FragmentActivity {
private static final int SPLASH = 0;
private static final int SELECTION = 1;
private static final int FRAGMENT_COUNT = SELECTION + 1;
private boolean isResumed = false;
private Fragment[] fragments = new Fragment[FRAGMENT_COUNT];
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
uiHelper = new UiLifecycleHelper(this, callback);
uiHelper.onCreate(savedInstanceState);
setContentView(R.layout.activity_dash_board);
FragmentManager fm = getSupportFragmentManager();
fragments[SPLASH] = fm.findFragmentById(R.id.splashFragment);
fragments[SELECTION] = fm.findFragmentById(R.id.selectionFragment);
FragmentTransaction transaction = fm.beginTransaction();
for (int i = 0; i < fragments.length; i++) {
transaction.hide(fragments[i]);
}
transaction.commit();
}
private void showFragment(int fragmentIndex, boolean addToBackStack) {
FragmentManager fm = getSupportFragmentManager();
FragmentTransaction transaction = fm.beginTransaction();
for (int i = 0; i < fragments.length; i++) {
if (i == fragmentIndex) {
transaction.show(fragments[i]);
} else {
transaction.hide(fragments[i]);
}
}
if (addToBackStack) {
transaction.addToBackStack(null);
}
transaction.commit();
}
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.main, menu);
return true;
}
public void facebookIntent(MenuItem item) {
startActivity(new Intent(this, Facebook.class));
}
public void twitterIntent(MenuItem item) {
startActivity(new Intent(this, Twitter.class));
}
public void dashboardIntent(MenuItem item) {
startActivity(new Intent(this, DashBoard.class));
}
public void redditIntent(MenuItem item) {
startActivity(new Intent(this, Reddit.class));
}
@Override
public void onResume() {
super.onResume();
isResumed = true;
uiHelper.onResume();
}
@Override
public void onPause() {
super.onPause();
uiHelper.onPause();
isResumed = false;
}
private void onSessionStateChange(Session session, SessionState state,
Exception exception) {
// Only make changes if the activity is visible
if (isResumed) {
FragmentManager manager = getSupportFragmentManager();
// Get the number of entries in the back stack
int backStackSize = manager.getBackStackEntryCount();
// Clear the back stack
for (int i = 0; i < backStackSize; i++) {
manager.popBackStack();
}
if (state.isOpened()) {
// If the session state is open:
// Show the authenticated fragment
showFragment(SELECTION, false);
} else if (state.isClosed()) {
// If the session state is closed:
// Show the login fragment
showFragment(SPLASH, false);
}
}
}
@Override
protected void onResumeFragments() {
super.onResumeFragments();
Session session = Session.getActiveSession();
if (session != null && session.isOpened()) {
// if the session is already open,
// try to show the selection fragment
showFragment(SELECTION, false);
} else {
// otherwise present the splash screen
// and ask the person to login.
showFragment(SPLASH, false);
}
}
private UiLifecycleHelper uiHelper;
private Session.StatusCallback callback = new Session.StatusCallback() {
@Override
public void call(Session session, SessionState state,
Exception exception) {
onSessionStateChange(session, state, exception);
}
};
@Override
public void onActivityResult(int requestCode, int resultCode, Intent data) {
super.onActivityResult(requestCode, resultCode, data);
uiHelper.onActivityResult(requestCode, resultCode, data);
}
@Override
public void onDestroy() {
super.onDestroy();
uiHelper.onDestroy();
}
@Override
protected void onSaveInstanceState(Bundle outState) {
super.onSaveInstanceState(outState);
uiHelper.onSaveInstanceState(outState);
}
}
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:orientation="vertical"
tools:context=".DashBoard" >
<fragment
android:id="@+id/selectionFragment"
android:name="com.example.social.SelectionFragment"
android:layout_width="match_parent"
android:layout_height="match_parent" />
<fragment
android:id="@+id/splashFragment"
android:name="com.example.social.SplashFragment"
android:layout_width="match_parent"
android:layout_height="match_parent" />
</LinearLayout>