setHomeButtonEnabled:java.lang.NullPointerException
每当我构建Android应用程序时,它都会生成以下错误:setHomeButtonEnabled:java.lang.NullPointerException,java,android,Java,Android,每当我构建Android应用程序时,它都会生成以下错误: 03-16 10:01:01.329 1312-1312/nl.mikehagendoorn.efteltijden E/AndroidRuntime﹕ FATAL EXCEPTION: main Process: nl.mikehagendoorn.efteltijden, PID: 1312 java.lang.RuntimeException: Unable to start activity Componen
03-16 10:01:01.329 1312-1312/nl.mikehagendoorn.efteltijden E/AndroidRuntime﹕ FATAL EXCEPTION: main
Process: nl.mikehagendoorn.efteltijden, PID: 1312
java.lang.RuntimeException: Unable to start activity ComponentInfo{nl.mikehagendoorn.efteltijden/nl.mikehagendoorn.efteltijden.MainActivity}: java.lang.NullPointerException
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2195)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2245)
at android.app.ActivityThread.access$800(ActivityThread.java:135)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1196)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:136)
at android.app.ActivityThread.main(ActivityThread.java:5017)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:515)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:779)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:595)
at dalvik.system.NativeStart.main(Native Method)
Caused by: java.lang.NullPointerException
at nl.mikehagendoorn.efteltijden.MainActivity.onCreate(MainActivity.java:85)
at android.app.Activity.performCreate(Activity.java:5231)
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1087)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2159)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2245)
at android.app.ActivityThread.access$800(ActivityThread.java:135)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1196)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:136)
at android.app.ActivityThread.main(ActivityThread.java:5017)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:515)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:779)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:595)
at dalvik.system.NativeStart.main(Native Method)
My MainActivity.java:
package nl.mikehagendoorn.efteltijden;
import android.app.ActionBar;
import android.app.FragmentTransaction;
import android.os.Bundle;
import android.support.v4.app.FragmentActivity;
import android.support.v4.view.ViewPager;
import android.widget.ListView;
import android.widget.ProgressBar;
import android.widget.TextView;
public class MainActivity extends FragmentActivity implements
ActionBar.TabListener {
private ListView listView1;
private ProgressBar loadingDialog;
private ViewPager viewPager;
private TabsPagerAdapter mAdapter;
private ActionBar actionBar;
TextView tvIsConnected;
TextView txtTitle;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
viewPager = (ViewPager) findViewById(R.id.pager);
actionBar = getActionBar();
mAdapter = new TabsPagerAdapter(getSupportFragmentManager());
viewPager.setAdapter(mAdapter);
actionBar.setHomeButtonEnabled(false);
actionBar.setNavigationMode(ActionBar.NAVIGATION_MODE_TABS);
// Tab titles
String[] tabs = {
getResources().getString(R.string.attractions),
getResources().getString(R.string.shows),
getResources().getString(R.string.horeca),
getResources().getString(R.string.stores),
getResources().getString(R.string.information)
};
// Adding Tabs
for (String tab_name : tabs) {
actionBar.addTab(actionBar.newTab().setText(tab_name)
.setTabListener(this));
}
/**
* on swiping the viewpager make respective tab selected
* */
viewPager.setOnPageChangeListener(new ViewPager.OnPageChangeListener() {
@Override
public void onPageSelected(int position) {
// on changing the page
// make respected tab selected
actionBar.setSelectedNavigationItem(position);
}
@Override
public void onPageScrolled(int arg0, float arg1, int arg2) {
}
@Override
public void onPageScrollStateChanged(int arg0) {
}
});
}
@Override
public void onTabSelected(ActionBar.Tab tab, FragmentTransaction ft) {
// on tab selected
// show respected fragment view
viewPager.setCurrentItem(tab.getPosition());
}
@Override
public void onTabUnselected(ActionBar.Tab tab, FragmentTransaction ft) {
}
@Override
public void onTabReselected(ActionBar.Tab tab, FragmentTransaction ft) {
}
}
然而,当我为安卓5.0构建它时,它不会抛出错误,它只是工作。
有人能告诉我我的代码出了什么问题吗
编辑——我正在使用SDK 16在模拟器中测试它。MinSDK版本为14,targetSdkVersion版本为21,您的模拟器可能运行的是Android<3.0,因此如果您想在那里使用ActionBar,请使用支持库和
actionBar=getActionBar()
可能应该是actionBar=getSupportActionBar
要像您这样使用AppCompat主题,您的活动需要从ActionBarActivity而不是FragmentActivity扩展(内部ActionBarActivity是FragmentActivity的扩展)你需要使用android.support.v7.app.ActionBar而不是android.app.ActionBar
也可以使用@Kim已经提到的getSupportActionBar()来代替getActionBar()。您在哪里测试它?它崩溃的测试设备的SDK是什么?你的min-required SDK是什么?我已经编辑了我的问题。编辑——我正在使用SDK 16的模拟器中测试它。模拟器的Android版本是4.1.2,你在MainActivity中使用的是哪个主题?也许这个主题不支持ActionBar?@Kim在我的清单中我添加了这一行:
android:theme=“@style/AppTheme”
你的AppTheme的父项是什么?