我想知道为什么我的应用程序在运行时抛出运行时异常?我习惯于在我的应用程序的以下链接中使用代码,动态地将视图添加到viewpager并将其删除。
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
ActionBar ab=getActionBar();
pagerAdapter = new MainPagerAdapter();
pager = (ViewPager) findViewById (R.id.pager);
pager.setAdapter (pagerAdapter);
inflater = (LayoutInflater)getSystemService
(Context.LAYOUT_INFLATER_SERVICE);
v0 = (FrameLayout) inflater.inflate (R.layout.listlayout, null);
Button button=(Button)findViewById(R.id.button1);
button.setOnClickListener(this);
pagerAdapter.addView (v0, 0);
pagerAdapter.notifyDataSetChanged();
}
@Override
public void onClick(View v) {
if(v.getId()==R.id.button1)
{
pagerAdapter.addView (v0);
pagerAdapter.notifyDataSetChanged();
}
}
日志:
FATAL EXCEPTION: main
java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.todolistworkable/com.example.todolistworkable.MainActivity}: java.lang.NullPointerException
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1970)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:1995)
at android.app.ActivityThread.access$600(ActivityThread.java:128)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1161)
at android.os.Handler.dispatchMessage(Handler.java:99)
at android.os.Looper.loop(Looper.java:137)
at android.app.ActivityThread.main(ActivityThread.java:4514)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:511)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:790)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:557)
at dalvik.system.NativeStart.main(Native Method)Caused by: java.lang.NullPointerException
at com.example.todolistworkable.MainActivity.onCreate(MainActivity.java:43)
at android.app.Activity.performCreate(Activity.java:4465)
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1053)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1934)
1条答案
按热度按时间kzipqqlq1#
oncreate方法中代码第43行的对象为空。很可能你的findviewbyid调用的目标没有返回你期望的结果。
有关详细信息,请参阅此。如何解释logcat