[英]actionbar NullPointerException with NewsReader Demo project
我尝试使用NewsReader来为我正在处理的事情派生代码,并且我遇到了操作栏的问题。 所以我决定只是重新创建NewsReader代码(对包名称进行合理的编辑等),我仍然遇到了同样的问题。
我在这个调用时遇到错误:
setUpActionBar(mIsDualPane, catIndex);
因为这条线:
actionBar.setDisplayShowTitleEnabled(false);
完整方法 :
public void setUpActionBar(boolean showTabs, int selTab) {
if (Build.VERSION.SDK_INT < 11) {
// No action bar for you!
// But do not despair. In this case the layout includes a bar across the
// top that looks and feels like an action bar, but is made up of regular views.
return;
}
android.app.ActionBar actionBar = getActionBar();
actionBar.setDisplayShowTitleEnabled(false);
// Set up a CompatActionBarNavHandler to deliver us the Action Bar nagivation events
CompatActionBarNavHandler handler = new CompatActionBarNavHandler(this);
if (showTabs) {
actionBar.setNavigationMode(android.app.ActionBar.NAVIGATION_MODE_TABS);
int i;
for (i = 0; i < CATEGORIES.length; i++) {
actionBar.addTab(actionBar.newTab().setText(CATEGORIES[i]).setTabListener(handler));
}
actionBar.setSelectedNavigationItem(selTab);
}
else {
actionBar.setNavigationMode(android.app.ActionBar.NAVIGATION_MODE_LIST);
SpinnerAdapter adap = new ArrayAdapter<String>(this, R.layout.actionbar_list_item,
CATEGORIES);
actionBar.setListNavigationCallbacks(adap, handler);
}
// Show logo instead of icon+title.
actionBar.setDisplayUseLogoEnabled(true);
}
似乎一些actionBar的东西也被弃用了,所以这可能是问题的一部分。 我该如何修复/更新?
堆栈跟踪:
06-16 09:24:21.211 24376-24376/com.anothergamedesigner.newsreader E/AndroidRuntime: FATAL EXCEPTION: main
Process: com.anothergamedesigner.newsreader, PID: 24376
java.lang.RuntimeException: Unable to start activity ComponentInfo{com.anothergamedesigner.newsreader/com.anothergamedesigner.newsreader.NewsReaderActivity}: java.lang.NullPointerException: Attempt to invoke virtual method 'void android.app.ActionBar.setDisplayShowTitleEnabled(boolean)' on a null object reference
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:3254)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:3350)
at android.app.ActivityThread.access$1100(ActivityThread.java:222)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1795)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:158)
at android.app.ActivityThread.main(ActivityThread.java:7229)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1230)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1120)
Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'void android.app.ActionBar.setDisplayShowTitleEnabled(boolean)' on a null object reference
at com.anothergamedesigner.newsreader.NewsReaderActivity.setUpActionBar(NewsReaderActivity.java:119)
at com.anothergamedesigner.newsreader.NewsReaderActivity.onCreate(NewsReaderActivity.java:81)
at android.app.Activity.performCreate(Activity.java:6876)
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1135)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:3207)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:3350)
at android.app.ActivityThread.access$1100(ActivityThread.java:222)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1795)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:158)
at android.app.ActivityThread.main(ActivityThread.java:7229)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1230)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1120)
更改
android.app.ActionBar actionBar = getActionBar();
至
ActionBar actionBar = getSupportActionBar();
编辑:
您还需要编辑styles.xml和AndroidManifest.xml。
在styles.xml中,进行更改
<style name="NewsReaderStyle" parent="android:Theme.Light.NoTitleBar">
至
<style name="NewsReaderStyle" parent="android:Theme.Light.DarkActionBar">
并在您的AndroidManifest.xml中进行更改
android:theme="@style/NewsReaderStyle_NoActionBar"
至
android:theme="@style/NewsReaderStyle"
AppCompat样式:
<style name="AppTheme" parent="Theme.AppCompat.Light.DarkActionBar">
<!-- Customize your theme here. -->
</style>
<style name="NoActionBarTheme" parent="Theme.AppCompat.Light.NoActionBar">
<!-- Customize your theme here. -->
</style>
现在将android:theme =“@ style / AppTheme”添加到您的清单中。
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