Java actionBar.setNavigationMode(ActionBar.NAVIGATION_MODE_TABS) 已弃用

actionBar.setNavigationMode(ActionBar.NAVIGATION_MODE_TABS) deprecated

提问by RashaadBryan

I'm following the tutorial https://www.youtube.com/watch?v=VVahIc8yENkand I'm getting the error

我正在按照教程https://www.youtube.com/watch?v=VVahIc8yENk 进行操作，但出现错误

java.lang.NullPointerException: Attempt to invoke virtual method 'void android.app.ActionBar.setNavigationMode(int)' on a null object reference

java.lang.NullPointerException：尝试在空对象引用上调用虚拟方法“void android.app.ActionBar.setNavigationMode(int)”

I'm using Android Studio to write this program and I have tried from API 11 to 21 and none of them work.

我正在使用 Android Studio 来编写这个程序，我已经尝试过从 API 11 到 21，但都没有工作。

public class Tabtest extends FragmentActivity implements ActionBar.TabListener {

    ActionBar actionBar;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_tab_test);

        actionBar=getActionBar();
        actionBar.setNavigationMode(ActionBar.NAVIGATION_MODE_TABS);

        ActionBar.Tab tab1=actionBar.newTab();
        tab1.setText("tab1");
        tab1.setTabListener(this);

        ActionBar.Tab tab2=actionBar.newTab();
        tab2.setText("tab2");
        tab2.setTabListener(this);

        ActionBar.Tab tab3=actionBar.newTab();
        tab3.setText("tab3");
        tab3.setTabListener(this);

        ActionBar.Tab tab4=actionBar.newTab();
        tab4.setText("tab4");
        tab4.setTabListener(this);

        actionBar.addTab(tab1);
        actionBar.addTab(tab2);
        actionBar.addTab(tab3);
        actionBar.addTab(tab4);
    }

    @Override
    public void onTabSelected(ActionBar.Tab tab, FragmentTransaction ft) {
        Log.d("VIVZ", "onTabReselected at "+" position "+tab.getPosition()+" name "+tab.getText());
    }

    @Override
    public void onTabUnselected(ActionBar.Tab tab, FragmentTransaction ft) {
        Log.d("VIVZ", "onTabReselected at "+" position "+tab.getPosition()+" name "+tab.getText());
    }

    @Override
    public void onTabReselected(ActionBar.Tab tab, FragmentTransaction ft) {
        Log.d("VIVZ", "onTabReselected at "+" position "+tab.getPosition()+" name "+tab.getText());
    }
}

回答by CommonsWare

java.lang.NullPointerException: Attempt to invoke virtual method 'void android.app.ActionBar.setNavigationMode(int)' on a null object reference

Your theme apparently is one that does not have an action bar. Since you are not using appcompat-v7, make sure that you are using a theme that supports the native action bar, such as one of the Theme.Holoseries.

您的主题显然是没有操作栏的主题。由于您没有使用appcompat-v7，请确保您使用的是支持本机操作栏的主题，例如Theme.Holo系列之一。

If, instead, you are trying to use appcompat-v7, you need to inherit from ActionBarActivityand you need to use getSupportActionBar(), not getActionBar().

相反，如果您尝试使用appcompat-v7，则需要继承自，ActionBarActivity并且需要使用getSupportActionBar()，而不是getActionBar()。

Also note that action bar tabs were deprecated as of Android 5.0. You should consider another tab solution, such as the combination of ViewPagerand PagerTabStrip.

另请注意，自 Android 5.0 起，不推荐使用操作栏选项卡。你应该考虑另一个选项卡的解决方案，比如组合ViewPager和PagerTabStrip。

回答by CommonsWare

I was following Vivz example in youtube but when the method deprecated i had to find another way. Instead of adding tabs to the actionbar try:

我在 youtube 上关注 Vivz 示例，但是当该方法被弃用时，我不得不找到另一种方法。不要向操作栏添加选项卡，请尝试：

Modify your adapter:

修改您的适配器：

public class CollectionPagerAdapter extends FragmentStatePagerAdapter {

    private String[] titles = {"Item 1", "Item 2", "Item 3" };

    public CollectionPagerAdapter(FragmentManager fm) {
        super(fm);
    }

    @Override
    public Fragment getItem(int i) {
        switch(i){
          case 0:
             return new FragmentA();
          case 1:
             return new FragmentB();
          case 2:
             return new FragmentC();        
        }
        return null;
    }

    @Override
    public int getCount() {
        return titles.length;
    }

    @Override
    public CharSequence getPageTitle(int position) {
        return titles[position];
    }
}

And in the activity that you would like to implement the tabs try

在您想要实现选项卡的活动中尝试

public class Tabtest extends ActionBarActivity{
@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_tab_test);

    ViewPager pager = (ViewPager) findViewById(R.id.your_view_pager);
    pager.setAdapter(new CollectionPagerAdapter(getSupportFragmentManager()));

    PagerSlidingTabStrip tabs = (PagerSlidingTabStrip) findViewById(R.id.tabs);
    tabs.setViewPager(pager);
}

Now if you would like to style your tabs like Google Play store with a moving indicator under the tab name and move while the user scrolls compile this library

现在，如果您想在选项卡名称下使用移动指示器设置像 Google Play 商店一样的选项卡样式，并在用户滚动时移动，请编译此库

compile 'com.astuetz:pagerslidingtabstrip:1.0.1'

And modify your viewpager layout file like this:

并像这样修改您的 viewpager 布局文件：

<LinearLayout
  //obviously add width and height and other necessery stuff
  android:orientation="vertical">

<com.astuetz.PagerSlidingTabStrip
    android:id="@+id/tabs"
    android:layout_width="match_parent"
    android:layout_height="48dip" />

<android.support.v4.view.ViewPager
    xmlns:android="http://schemas.android.com/apk/res/android"
    android:id="@+id/pager"
    android:layout_width="match_parent"
    android:layout_height="match_parent" />


</LinearLayout>

And then you are going to have the desired effect.

然后你就会有想要的效果。

Hope it helps!!!

希望能帮助到你！！！

回答by Hojjat Mehri

finally i found answer. 1st your android sdk

最后我找到了答案。第一个你的安卓 sdk

<uses-sdk android:minSdkVersion="11" />

it must higher than 11. 2nd your theme must have actionbar like

它必须高于 11。第二你的主题必须有像这样的操作栏

android:theme="Theme.AppCompat"

3rd don't use this code in your activity

第三，不要在您的活动中使用此代码

requestWindowFeature(Window.FEATURE_NO_TITLE);

4th instead of import android.support.v4.app.ActionBaruse import android.support.v7.app.ActionBarin your activity

4th 而不是在您的活动中import android.support.v4.app.ActionBar使用import android.support.v7.app.ActionBar

5th change this actionBar=getActionBar();to actionbar=getSupportActionBar();

5th 将此更改actionBar=getActionBar();为actionbar=getSupportActionBar();

回答by David Hackro

you can use "PagerSlidingTabStrip" replacing "setNavigationMode"

您可以使用“ PagerSlidingTabStrip”替换“ setNavigationMode”

here a tutorialand here a examplein Github

这里有教程，这里有Github 中的示例