我正在我正在处理的应用程序中将标签视图或（ViewPager）添加到我的Fragment中。
我想将标签视图放在Contact Fragment
中我打开了一个导航抽屉，您会看到选项列表......
主
服务
与
您点击的所有内容都会转到片段
然后在该片段中加载.XML文件，并使用相应的类对.XML文件中的所有内容进行编程。
我正在关注在线教程[点击这里] [3]
显然是2年多前了。 Android代码从那时起发生了变化。我开始时遇到了一些错误，而不是我现在拥有的错误。
我遇到了 getSupportFragmentManager（）的问题， getActionBar（）此时真的很困惑，所有导入都在那里。它不会认识到这两者。显然，这让我觉得缺少了一些东西，但我不确定需要让编译器看到那些所需的方法。
设置ViewPager setAdapter时，我仍然会显示Null。
我想要完成的是一个标签视图，其中包含两个用于联系人和社交媒体的标签。如果我能够简单地理解标签正常工作所需的内容。
我已经搜索了问题，他们并没有完全触及我的具体问题，所以我正在寻求帮助。任何帮助肯定是赞赏。
FragmentContact
package com.megliosolutions.bitsnbytes.Fragments;
import android.app.Activity;
import android.os.Bundle;
import android.support.v4.app.FragmentActivity;
import android.support.v4.app.FragmentManager;
import android.support.v4.view.ViewPager;
import android.support.v7.app.ActionBar;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import com.megliosolutions.bitsnbytes.MainActivity;
import com.megliosolutions.bitsnbytes.R;
import com.megliosolutions.bitsnbytes.ViewPagerClasses.TabsPagerAdapter;
/**
* Created by Jarvis on 6/21/15.
*/
public class FragmentContact extends Fragment {
private ViewPager viewPager;
TabsPagerAdapter mAdapter;
private ActionBar actionBar;
private String[] tabs = {"Contact", "Social Media"};
public static FragmentContact newInstance(){
FragmentContact fragment = new FragmentContact();
return fragment;
}
public FragmentContact(){};
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View rootView = inflater.inflate(R.layout.fragment_contact, container, false);
LoadTabs(rootView);
return rootView;
}
private void LoadTabs(View rootView) {
FragmentManager fragmentManager = getSupportFragmentManager();
// Initilization
viewPager = (ViewPager) rootView.findViewById(R.id.pager);
actionBar = getActionBar();
mAdapter = new TabsPagerAdapter(fragmentManager);
viewPager.setAdapter(mAdapter);
actionBar.setHomeButtonEnabled(false);
actionBar.setNavigationMode(ActionBar.NAVIGATION_MODE_TABS);
// Adding Tabs
for (String tab_name : tabs) {
actionBar.addTab(actionBar.newTab().setText(tab_name)
.setTabListener((ActionBar.TabListener) this));
}
}
@Override
public void onAttach(FragmentActivity activity) {
super.onAttach(activity);
((MainActivity) activity).onSectionAttached(5);
}
}
TabsPagerAdapter
package com.megliosolutions.bitsnbytes.ViewPagerClasses;
import android.support.v4.app.Fragment;
import android.support.v4.app.FragmentManager;
import android.support.v4.app.FragmentPagerAdapter;
import android.view.View;
/**
* Created by Jarvis on 6/28/15.
*/
public class TabsPagerAdapter extends FragmentPagerAdapter {
public TabsPagerAdapter(FragmentManager fm) {
super(fm);
}
@Override
public Fragment getItem(int index) {
switch (index) {
case 0:
// Contact fragment activity
return new ContactFragment();
case 1:
// Social Media fragment activity
return new SocialMediaFragment();
}
return null;
}
@Override
public int getCount() {
// get item count - equal to number of tabs
return 2;
}
@Override
public boolean isViewFromObject(View view, Object object) {
return false;
}
}
MAINACTIVITY
package com.megliosolutions.bitsnbytes;
import android.app.Activity;
import android.os.Bundle;
import android.support.v4.app.ActionBarDrawerToggle;
import android.support.v4.app.Fragment;
import android.support.v4.app.FragmentManager;
import android.support.v4.widget.DrawerLayout;
import android.support.v7.app.ActionBar;
import android.support.v7.app.ActionBarActivity;
import android.view.LayoutInflater;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.view.ViewGroup;
import com.megliosolutions.bitsnbytes.Fragments.FragmentAbout;
import com.megliosolutions.bitsnbytes.Fragments.FragmentContact;
import com.megliosolutions.bitsnbytes.Fragments.FragmentHome;
import com.megliosolutions.bitsnbytes.Fragments.FragmentProducts;
import com.megliosolutions.bitsnbytes.Fragments.FragmentServices;
import com.megliosolutions.bitsnbytes.Fragments.FragmentWarranties;
public class MainActivity extends ActionBarActivity
implements NavigationDrawerFragment.NavigationDrawerCallbacks {
/**
* Fragment managing the behaviors, interactions and presentation of the navigation drawer.
*/
private NavigationDrawerFragment mNavigationDrawerFragment;
/**
* Used to store the last screen title. For use in {@link #restoreActionBar()}.
*/
private CharSequence mTitle;
private ActionBarDrawerToggle mDrawerToggle;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
mNavigationDrawerFragment = (NavigationDrawerFragment)
getSupportFragmentManager().findFragmentById(R.id.navigation_drawer);
mTitle = getTitle();
// Set up the drawer.
mNavigationDrawerFragment.setUp(
R.id.navigation_drawer,
(DrawerLayout) findViewById(R.id.drawer_layout));
}
@Override
public void onNavigationDrawerItemSelected(int position) {
// update the main content by replacing fragments
FragmentManager fragmentManager = getSupportFragmentManager();
if(position == 0) {
fragmentManager.beginTransaction()
.replace(R.id.container, FragmentHome.newInstance())
.commit();
}
else if(position == 1){
fragmentManager.beginTransaction()
.replace(R.id.container, FragmentServices.newInstance())
.commit();
}
else if(position == 2){
fragmentManager.beginTransaction()
.replace(R.id.container, FragmentProducts.newInstance())
.commit();
}
else if(position == 3){
fragmentManager.beginTransaction()
.replace(R.id.container, FragmentWarranties.newInstance())
.commit();
}
else if(position == 4){
fragmentManager.beginTransaction()
.replace(R.id.container, FragmentContact.newInstance())
.commit();
}
else if(position == 5){
fragmentManager.beginTransaction()
.replace(R.id.container, FragmentAbout.newInstance())
.commit();
}
}
public void onSectionAttached(int number) {
switch (number) {
case 1:
mTitle = getString(R.string.title_section1);
break;
case 2:
mTitle = getString(R.string.title_section2);
break;
case 3:
mTitle = getString(R.string.title_section3);
break;
case 4:
mTitle = getString(R.string.title_section4);
break;
case 5:
mTitle = getString(R.string.title_section5);
break;
case 6:
mTitle = getString(R.string.title_section6);
}
}
public void restoreActionBar() {
ActionBar actionBar = getSupportActionBar();
actionBar.setNavigationMode(ActionBar.NAVIGATION_MODE_STANDARD);
actionBar.setDisplayShowTitleEnabled(true);
actionBar.setTitle(mTitle);
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
if (!mNavigationDrawerFragment.isDrawerOpen()) {
// Only show items in the action bar relevant to this screen
// if the drawer is not showing. Otherwise, let the drawer
// decide what to show in the action bar.
getMenuInflater().inflate(R.menu.main, menu);
restoreActionBar();
return true;
}
return super.onCreateOptionsMenu(menu);
}
@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);
}
/**
* A placeholder fragment containing a simple view.
*/
public static class PlaceholderFragment extends Fragment {
/**
* The fragment argument representing the section number for this
* fragment.
*/
private static final String ARG_SECTION_NUMBER = "section_number";
/**
* Returns a new instance of this fragment for the given section
* number.
*/
public static PlaceholderFragment newInstance(int sectionNumber) {
PlaceholderFragment fragment = new PlaceholderFragment();
Bundle args = new Bundle();
args.putInt(ARG_SECTION_NUMBER, sectionNumber);
fragment.setArguments(args);
return fragment;
}
public PlaceholderFragment() {
}
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View rootView = inflater.inflate(R.layout.fragment_main, container, false);
return rootView;
}
@Override
public void onAttach(Activity activity) {
super.onAttach(activity);
((MainActivity) activity).onSectionAttached(
getArguments().getInt(ARG_SECTION_NUMBER));
}
}
}
现在onNavigationDrawerItemSelected（）中的FragmentContact.newInstance（）存在问题
06-28 15:35:24.695 11744-11744/com.megliosolutions.bitsnbytes E/AndroidRuntime﹕ FATAL EXCEPTION: main
Process: com.megliosolutions.bitsnbytes, PID: 11744
java.lang.NullPointerException: Attempt to invoke virtual method 'void android.support.v4.view.ViewPager.setAdapter(android.support.v4.view.PagerAdapter)' on a null object reference
at com.megliosolutions.bitsnbytes.Fragments.FragmentContact.LoadTabs(FragmentContact.java:55)
at com.megliosolutions.bitsnbytes.Fragments.FragmentContact.onCreateView(FragmentContact.java:43)
at android.support.v4.app.Fragment.performCreateView(Fragment.java:1789)
at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:955)
at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:1138)
at android.support.v4.app.BackStackRecord.run(BackStackRecord.java:740)
at android.support.v4.app.FragmentManagerImpl.execPendingActions(FragmentManager.java:1501)
at android.support.v4.app.FragmentManagerImpl$1.run(FragmentManager.java:458)
at android.os.Handler.handleCallback(Handler.java:739)
at android.os.Handler.dispatchMessage(Handler.java:95)
at android.os.Looper.loop(Looper.java:135)
at android.app.ActivityThread.main(ActivityThread.java:5254)
at java.lang.reflect.Method.invoke(Native Method)
at java.lang.reflect.Method.invoke(Method.java:372)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:903)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:698)
答案 0 :(得分：1)
来自logcat错误它的清晰ViewPager不存在于R.layout.fragment_contact中。请验证。
答案 1 :(得分：0)
由于我需要引用存在于activity_main.xml上的viewPager而不是当前片段，因此我设法解决了该错误：
我添加了一个新视图的声明，该声明引用了ViewPager存在的活动，如下所示：
View viewNext = inflater.inflate(R.layout.activity_main, container, false);
然后，关于上述声明，我声明了viewPager：
viewPager = (ViewPager) viewNext.findViewById(R.id.viewPager);
然后，我设置了适配器。