我得到以下空指针异常。每当我点击按钮（我意图启动）。我得到一个FC和这个nullpointer异常。可能是因为使用了那个文本文件吗？
04-25 20:02:40.762: I/Adreno200-EGLSUB(29671): <ConfigWindowMatch:2081>: Format RGBA_8888.
04-25 20:02:40.772: D/memalloc(29671): /dev/pmem: Mapped buffer base:0x514e1000 size:3649536 offset:3035136 fd:56
04-25 20:02:40.982: D/memalloc(29671): /dev/pmem: Mapped buffer base:0x51b08000 size:4325376 offset:3710976 fd:59
04-25 20:02:41.632: I/Adreno200-EGLSUB(29671): <ConfigWindowMatch:2081>: Format RGBA_8888.
04-25 20:02:41.632: D/memalloc(29671): /dev/pmem: Mapped buffer base:0x5212e000 size:4939776 offset:4325376 fd:62
04-25 20:02:41.692: D/memalloc(29671): /dev/pmem: Mapped buffer base:0x52615000 size:5554176 offset:4939776 fd:68
04-25 20:02:41.712: D/memalloc(29671): /dev/pmem: Unmapping buffer base:0x514e1000 size:3649536 offset:3035136
04-25 20:02:41.712: D/memalloc(29671): /dev/pmem: Unmapping buffer base:0x51b08000 size:4325376 offset:3710976
04-25 20:02:42.842: D/memalloc(29671): /dev/pmem: Mapped buffer base:0x513e1000 size:4325376 offset:3710976 fd:53
04-25 20:02:42.882: W/dalvikvm(29671): threadid=1: thread exiting with uncaught exception (group=0x40dbb9d8)
04-25 20:02:42.902: E/AndroidRuntime(29671): FATAL EXCEPTION: main
04-25 20:02:42.902: E/AndroidRuntime(29671): java.lang.RuntimeException: Unable to instantiate activity ComponentInfo{com.dreamgoogle.gihf/com.dreamgoogle.gihf.Stories}: java.lang.NullPointerException
04-25 20:02:42.902: E/AndroidRuntime(29671): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1884)
04-25 20:02:42.902: E/AndroidRuntime(29671): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:1985)
04-25 20:02:42.902: E/AndroidRuntime(29671): at android.app.ActivityThread.access$600(ActivityThread.java:127)
04-25 20:02:42.902: E/AndroidRuntime(29671): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1151)
04-25 20:02:42.902: E/AndroidRuntime(29671): at android.os.Handler.dispatchMessage(Handler.java:99)
04-25 20:02:42.902: E/AndroidRuntime(29671): at android.os.Looper.loop(Looper.java:137)
04-25 20:02:42.902: E/AndroidRuntime(29671): at android.app.ActivityThread.main(ActivityThread.java:4476)
04-25 20:02:42.902: E/AndroidRuntime(29671): at java.lang.reflect.Method.invokeNative(Native Method)
04-25 20:02:42.902: E/AndroidRuntime(29671): at java.lang.reflect.Method.invoke(Method.java:511)
04-25 20:02:42.902: E/AndroidRuntime(29671): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:816)
04-25 20:02:42.902: E/AndroidRuntime(29671): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:583)
04-25 20:02:42.902: E/AndroidRuntime(29671): at dalvik.system.NativeStart.main(Native Method)
04-25 20:02:42.902: E/AndroidRuntime(29671): Caused by: java.lang.NullPointerException
04-25 20:02:42.902: E/AndroidRuntime(29671): at android.app.Activity.findViewById(Activity.java:1965)
04-25 20:02:42.902: E/AndroidRuntime(29671): at com.dreamgoogle.gihf.Stories.<init>(Stories.java:14)
04-25 20:02:42.902: E/AndroidRuntime(29671): at java.lang.Class.newInstanceImpl(Native Method)
04-25 20:02:42.902: E/AndroidRuntime(29671): at java.lang.Class.newInstance(Class.java:1319)
04-25 20:02:42.902: E/AndroidRuntime(29671): at android.app.Instrumentation.newActivity(Instrumentation.java:1025)
04-25 20:02:42.902: E/AndroidRuntime(29671): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1875)
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="wrap_content"
android:layout_height="wrap_content" >
<TextView
android:id="@+id/jobsdes"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentLeft="true"
android:layout_alignParentTop="true"
android:text="@string/sj1" />
</RelativeLayout>
public class Stories extends Activity {
TextView t1 = (TextView) findViewById(R.id.jobsdes);
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_stories);
MyPagerAdapter adapter = new MyPagerAdapter();
ViewPager myPager = (ViewPager) findViewById(R.id.pager1);
myPager.setAdapter(adapter);
myPager.setCurrentItem(0);
t1.setText(R.raw.jobs);
}
private class MyPagerAdapter extends PagerAdapter {
public int getCount() {
return 4;
}
public Object instantiateItem(View collection, int position) {
LayoutInflater inflater = (LayoutInflater) collection.getContext()
.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
int resId = 0;
switch (position) {
case 0:
resId = R.layout.activity_stories;
break;
case 1:
resId = R.layout.sto2;
break;
case 2:
resId = R.layout.sto3;
break;
case 3:
resId = R.layout.sto4;
break;
}
View view = inflater.inflate(resId, null);
((ViewPager) collection).addView(view, 0);
return view;
}
public void destroyItem(View arg0, int arg1, Object arg2) {
((ViewPager) arg0).removeView((View) arg2);
}
public boolean isViewFromObject(View arg0, Object arg1) {
return arg0 == ((View) arg1);
}
public Parcelable saveState() {
return null;
}
}
}
这里是寻呼机xml文件。
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:paddingBottom="@dimen/activity_vertical_margin"
android:paddingLeft="@dimen/activity_horizontal_margin"
android:paddingRight="@dimen/activity_horizontal_margin"
android:paddingTop="@dimen/activity_vertical_margin"
tools:context=".Stories" >
<android.support.v4.view.ViewPager
android:id="@+id/pager1"
android:layout_width="match_parent"
android:layout_height="match_parent" />
</RelativeLayout>
答案 0 :(得分：4)
异常
04-25 20：02：42.902：E / AndroidRuntime（29671）：引起： java.lang.NullPointerException 04-25 20：02：42.902： E / AndroidRuntime（29671）：at android.app.Activity.findViewById（Activity.java:1965）
代码
findViewById(R.id.pager1)
XML
android:id="@+id/jobsdes"
我想说，你的findViewbyId返回零
答案 1 :(得分：2)
您试图在活动中找到TextView之前：
public class Stories extends Activity {
TextView t1 = (TextView) findViewById(R.id.jobsdes); //RIGHT HERE
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_stories);
您需要在setContentView之后找到它，如下所示：
public class Stories extends Activity {
TextView t1;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_stories);
t1 = (TextView) findViewById(R.id.josdes);
答案 2 :(得分：0)
在setcontentview之后访问TextView并且这样做。