java - 在 Android 应用程序中获取 ClassCastException

Question

启动以下 Activity 时，我收到了 ClassCastException。

我的布局:

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

我的 Activity 类:

public class NewDialogsActivity extends ActionBarActivity {

    private SectionsPagerAdapter sectionsPagerAdapter;
    private ViewPager viewPager;

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

        final ActionBar actionBar = getSupportActionBar();
        actionBar.setNavigationMode(ActionBar.NAVIGATION_MODE_TABS);

        List<Fragment> tabs = new ArrayList<Fragment>();
        tabs.add(UserFragment.getInstance());

        sectionsPagerAdapter = new SectionsPagerAdapter(getSupportFragmentManager(), tabs);

        viewPager = (ViewPager) findViewById(R.id.pager);
        viewPager.setAdapter(sectionsPagerAdapter);

        viewPager.setOnPageChangeListener(new ViewPager.SimpleOnPageChangeListener() {
            @Override
            public void onPageSelected(int position) {
                actionBar.setSelectedNavigationItem(position);
            }
        });
    }

    public static class SectionsPagerAdapter extends FragmentPagerAdapter {

        private List<Fragment> fragments;

        public SectionsPagerAdapter(FragmentManager fm, List<Fragment> fragments) {
            super(fm);
            this.fragments = fragments;
        }

        @Override
        public Fragment getItem(int position) {
            return fragments.get(position);
        }

        @Override
        public int getCount() {
            return fragments.size();
        }

        @Override
        public CharSequence getPageTitle(int position) {
            return "Users";
        }
    }

    @Override
    public void onBackPressed() {
        Intent i = new Intent(NewDialogsActivity.this, DialogsActivity.class);
        startActivity(i);
        finish();

    }
}

我在我的代码中使用了这个主题

<style name="AppTheme" parent="Theme.AppCompat.Light.DarkActionBar">
    <item name="android:windowNoTitle">false</item>
    <item name="android:windowActionBar">true</item>
</style>

日志

E/AndroidRuntime﹕ FATAL EXCEPTION: main
java.lang.ClassCastException: android.support.v7.internal.widget.ActionBarOverlayLayout$LayoutParams cannot be cast to com.android.internal.widget.ActionBarOverlayLayout$LayoutParams
        at com.android.internal.widget.ActionBarOverlayLayout.applyInsets(ActionBarOverlayLayout.java:147)
        at com.android.internal.widget.ActionBarOverlayLayout.onMeasure(ActionBarOverlayLayout.java:292)
        at android.view.View.measure(View.java:16030)
        at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5012)
        at android.widget.FrameLayout.onMeasure(FrameLayout.java:314)
        at com.android.internal.policy.impl.PhoneWindow$DecorView.onMeasure(PhoneWindow.java:2196)
        at android.view.View.measure(View.java:16030)
        at android.view.ViewRootImpl.performMeasure(ViewRootImpl.java:1915)
        at android.view.ViewRootImpl.measureHierarchy(ViewRootImpl.java:1109)
        at android.view.ViewRootImpl.performTraversals(ViewRootImpl.java:1290)
        at android.view.ViewRootImpl.doTraversal(ViewRootImpl.java:1009)
        at android.view.ViewRootImpl$TraversalRunnable.run(ViewRootImpl.java:5508)
        at android.view.Choreographer$CallbackRecord.run(Choreographer.java:749)
        at android.view.Choreographer.doCallbacks(Choreographer.java:562)
        at android.view.Choreographer.doFrame(Choreographer.java:532)
        at android.view.Choreographer$FrameDisplayEventReceiver.run(Choreographer.java:735)
        at android.os.Handler.handleCallback(Handler.java:730)
        at android.os.Handler.dispatchMessage(Handler.java:92)
        at android.os.Looper.loop(Looper.java:213)
        at android.app.ActivityThread.main(ActivityThread.java:5225)
        at java.lang.reflect.Method.invokeNative(Native Method)
        at java.lang.reflect.Method.invoke(Method.java:525)
        at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:741)
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:557)
        at dalvik.system.NativeStart.main(Native Method)

谁能帮我看看这段代码有什么问题。

minSdk=14
targetSdk=21

Answer 1

原因如下:

java.lang.ClassCastException: android.support.v7.internal.widget.ActionBarOverlayLayout$LayoutParams cannot be cast to com.android.internal.widget.ActionBarOverlayLayout$LayoutParams

所以基本上您不应该将“原生”ActionBar 与支持库的 ActionBar 混合使用。选择并使用其中一个。很可能你的代码中的 import 不正确，因此请检查你的源代码是否有 import com.android.internal.widget.ActionBarOverlayLayout; 左右并删除然后添加正确的 import android.support.v7.internal.widget.ActionBarOverlayLayout; 或者使用你的 IDE 的“organize imports”功能，然后确保使用支持库的相关功能(IDE 会询问)