我有一个使用 listview 元素的活动，如下所示
public class List1 extends Activity
{
Context context=this;
@Override
public void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
setContentView(R.layout.listview);
try{
//DB
final SQLiteDatabase db;
db = openOrCreateDatabase(
"Secret.db"
, SQLiteDatabase.CREATE_IF_NECESSARY
, null
);
db.setVersion(1);
db.setLocale(Locale.getDefault());
db.setLockingEnabled(true);
Cursor cur = db.query("tbl_user",null,null,null,null,null,null);
//DB Over
ListView listView = (ListView) findViewById(R.id.mylist);
listView.setTextFilterEnabled(true);
final String[] values = new String[50];
int i=0;
while(cur.moveToNext())
{
values[i]=Integer.toString(cur.getInt(0))+":"+cur.getString(1)+":"+cur.getString(2);
i++;
}
cur.close();
ArrayAdapter<String> adapter = new ArrayAdapter<String>(context,R.layout.list_item,values);
listView.setAdapter(adapter);
listView.setVisibility(0);
listView.setOnItemClickListener(new AdapterView.OnItemClickListener() {
public void onItemClick(AdapterView<?> parent, View view, int position,long id)
//public void onItemClick(ListView<?> listview, View view, int position,long id)
{
try
{
Intent i=new Intent(List1.this,Form1.class);
i.putExtra("uid","85");
startActivity(i);
finish();
}
catch(Exception e)
{
String insert2="insert into login values("+"\""+e.toString()+"\""+");";
db.execSQL(insert2);
}
}
});
db.close();
//required
}
catch(Exception e)
{
Toast.makeText(getApplicationContext(), e.toString(), Toast.LENGTH_LONG).show();}
}
}
这是我的 listview.xml 文件
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="fill_parent"
android:layout_height="fill_parent" >
<ListView
android:id="@+id/mylist"
android:layout_width="fill_parent"
android:layout_height="wrap_content" >
</ListView>
</RelativeLayout>
这是我的 list_item.xml 文件，其中包含所需的 textview
<?xml version="1.0" encoding="utf-8"?>
<TextView xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:id="@+id/tv1"
android:padding="10dp"
android:background="@drawable/textview1"
style="@style/textview_text"
android:textSize="16dp">
</TextView>
但是 ListView 不起作用。我的意思是在参加此活动后，应用程序显示错误，显示“APP_NAME 意外停止”。相同的代码工作一两次，然后连续显示上述错误。我可以知道为什么会这样吗？
编辑
这是 logcat 文件
W/dalvikvm( 2694): threadid=3: thread exiting with uncaught exception (group=0x4
001b188)
E/AndroidRuntime( 2694): Uncaught handler: thread main exiting due to uncaught e
xception
E/AndroidRuntime( 2694): java.lang.NullPointerException
E/AndroidRuntime( 2694): at android.widget.ArrayAdapter.createViewFromRes
ource(ArrayAdapter.java:355)
E/AndroidRuntime( 2694): at android.widget.ArrayAdapter.getView(ArrayAdap
ter.java:323)
E/AndroidRuntime( 2694): at android.widget.AbsListView.obtainView(AbsList
View.java:1274)
E/AndroidRuntime( 2694): at android.widget.ListView.makeAndAddView(ListVi
ew.java:1668)
E/AndroidRuntime( 2694): at android.widget.ListView.fillDown(ListView.jav
a:637)
E/AndroidRuntime( 2694): at android.widget.ListView.fillFromTop(ListView.
java:694)
E/AndroidRuntime( 2694): at android.widget.ListView.layoutChildren(ListVi
ew.java:1521)
E/AndroidRuntime( 2694): at android.widget.AbsListView.onLayout(AbsListVi
ew.java:1113)
E/AndroidRuntime( 2694): at android.view.View.layout(View.java:6830)
E/AndroidRuntime( 2694): at android.widget.RelativeLayout.onLayout(Relati
veLayout.java:900)
E/AndroidRuntime( 2694): at android.view.View.layout(View.java:6830)
E/AndroidRuntime( 2694): at android.widget.FrameLayout.onLayout(FrameLayo
ut.java:333)
E/AndroidRuntime( 2694): at android.view.View.layout(View.java:6830)
E/AndroidRuntime( 2694): at android.widget.LinearLayout.setChildFrame(Lin
earLayout.java:1119)
E/AndroidRuntime( 2694): at android.widget.LinearLayout.layoutVertical(Li
nearLayout.java:998)
E/AndroidRuntime( 2694): at android.widget.LinearLayout.onLayout(LinearLa
yout.java:918)
E/AndroidRuntime( 2694): at android.view.View.layout(View.java:6830)
E/AndroidRuntime( 2694): at android.widget.FrameLayout.onLayout(FrameLayo
ut.java:333)
E/AndroidRuntime( 2694): at android.view.View.layout(View.java:6830)
E/AndroidRuntime( 2694): at android.view.ViewRoot.performTraversals(ViewR
oot.java:996)
E/AndroidRuntime( 2694): at android.view.ViewRoot.handleMessage(ViewRoot.
java:1633)
E/AndroidRuntime( 2694): at android.os.Handler.dispatchMessage(Handler.ja
va:99)
E/AndroidRuntime( 2694): at android.os.Looper.loop(Looper.java:123)
E/AndroidRuntime( 2694): at android.app.ActivityThread.main(ActivityThrea
d.java:4363)
E/AndroidRuntime( 2694): at java.lang.reflect.Method.invokeNative(Native
Method)
E/AndroidRuntime( 2694): at java.lang.reflect.Method.invoke(Method.java:5
21)
E/AndroidRuntime( 2694): at com.android.internal.os.ZygoteInit$MethodAndA
rgsCaller.run(ZygoteInit.java:860)
E/AndroidRuntime( 2694): at com.android.internal.os.ZygoteInit.main(Zygot
eInit.java:618)
E/AndroidRuntime( 2694): at dalvik.system.NativeStart.main(Native Method)
D/dalvikvm( 2694): GC freed 6621 objects / 343272 bytes in 126ms
I/dalvikvm( 2694): Uncaught exception thrown by finalizer (will be discarded):
I/dalvikvm( 2694): Ljava/lang/IllegalStateException;: Finalizing cursor android.
database.sqlite.SQLiteCursor@44c60cd0 on login that has not been deactivated or
closed
I/dalvikvm( 2694): at android.database.sqlite.SQLiteCursor.finalize(SQLiteC
ursor.java:596)
I/dalvikvm( 2694): at dalvik.system.NativeStart.run(Native Method)
I/dalvikvm( 2694): Uncaught exception thrown by finalizer (will be discarded):
I/dalvikvm( 2694): Ljava/lang/IllegalStateException;: Finalizing cursor android.
database.sqlite.SQLiteCursor@44c58028 on login that has not been deactivated or
closed
I/dalvikvm( 2694): at android.database.sqlite.SQLiteCursor.finalize(SQLiteC
ursor.java:596)
I/dalvikvm( 2694): at dalvik.system.NativeStart.run(Native Method)
I/dalvikvm( 2694): Uncaught exception thrown by finalizer (will be discarded):
I/dalvikvm( 2694): Ljava/lang/IllegalStateException;: Finalizing cursor android.
database.sqlite.SQLiteCursor@44c37fa0 on login that has not been deactivated or
closed
I/dalvikvm( 2694): at android.database.sqlite.SQLiteCursor.finalize(SQLiteC
ursor.java:596)
I/dalvikvm( 2694): at dalvik.system.NativeStart.run(Native Method)
I/Process ( 52): Sending signal. PID: 2694 SIG: 3
I/dalvikvm( 2694): threadid=7: reacting to signal 3
I/dalvikvm( 2694): Wrote stack trace to '/data/anr/traces.txt'
I/Process ( 2694): Sending signal. PID: 2694 SIG: 9
I/ActivityManager( 52): Process com.notification (pid 2694) has died.
I/WindowManager( 52): WIN DEATH: Window{44d90538 com.notification/com.notifica
tion.List1 paused=false}
I/UsageStats( 52): Unexpected resume of com.android.launcher while already res
umed in com.notification
W/InputManagerService( 52): Window already focused, ignoring focus gain of: co
m.android.internal.view.IInputMethodClient$Stub$Proxy@44d933c8
I/ActivityManager( 52): Start proc com.notification for broadcast com.notifica
tion/.AlarmReceiver: pid=2706 uid=10034 gids={3003}
D/ddm-heap( 2706): Got feature list request
D/dalvikvm( 1152): GC freed 194 objects / 8728 bytes in 88ms
I/ActivityManager( 52): Starting activity: Intent { act=android.intent.action.
MAIN cat=[android.intent.category.LAUNCHER] flg=0x10200000 cmp=com.notification/
.NotificationActivity }
I/ActivityManager( 52): Starting activity: Intent { cmp=com.notification/.Back
ground }
I/ActivityManager( 52): Displayed activity com.notification/.Background: 262 m
s (total 8081 ms)
D/dalvikvm( 234): GC freed 44 objects / 2064 bytes in 134ms
D/AndroidRuntime( 2718):
D/AndroidRuntime( 2718): >>>>>>>>>>>>>> AndroidRuntime START <<<<<<<<<<<<<<
D/AndroidRuntime( 2718): CheckJNI is ON
D/AndroidRuntime( 2718): --- registering native functions ---
D/ddm-heap( 2718): Got feature list request
D/PackageParser( 52): Scanning package: /data/app/vmdl67950.tmp
I/PackageManager( 52): Removing non-system package:com.notification
D/PackageManager( 52): Removing package com.notification
D/PackageManager( 52): Services: com.notification.BackService
D/PackageManager( 52): Receivers: com.notification.AlarmReceiver
D/PackageManager( 52): Activities: com.notification.NotificationActivity com
.notification.Form1 com.notification.Background com.notification.Bg com.notifica
tion.List1
W/InputManagerService( 52): Window already focused, ignoring focus gain of: co
m.android.internal.view.IInputMethodClient$Stub$Proxy@44eb1868
D/PackageManager( 52): Scanning package com.notification
I/PackageManager( 52): /data/app/vmdl67950.tmp changed; unpacking
D/installd( 32): DexInv: --- BEGIN '/data/app/vmdl67950.tmp' ---
D/dalvikvm( 2724): DexOpt: load 40ms, verify 159ms, opt 2ms
D/installd( 32): DexInv: --- END '/data/app/vmdl67950.tmp' (success) ---
D/PackageManager( 52): Services: com.notification.BackService
D/PackageManager( 52): Receivers: com.notification.AlarmReceiver
D/PackageManager( 52): Activities: com.notification.NotificationActivity com
.notification.Form1 com.notification.Background com.notification.Bg com.notifica
tion.List1
D/ActivityManager( 52): Uninstalling process com.notification
D/ActivityManager( 52): Force removing process ProcessRecord{44e9eb48 2706:com
.notification/10034} (com.notification/10034)
I/Process ( 52): Sending signal. PID: 2706 SIG: 9
D/ActivityManager( 52): Received spurious death notification for thread androi
d.os.BinderProxy@44eec8b8
I/installd( 32): move /data/dalvik-cache/data@app@vmdl67950.tmp@classes.dex ->
/data/dalvik-cache/data@app@com.notification.apk@classes.dex
D/PackageManager( 52): New package installed in /data/app/com.notification.apk
D/AndroidRuntime( 2718): Shutting down VM
D/dalvikvm( 2718): DestroyJavaVM waiting for non-daemon threads to exit
D/dalvikvm( 2718): DestroyJavaVM shutting VM down
D/dalvikvm( 2718): HeapWorker thread shutting down
D/dalvikvm( 2718): HeapWorker thread has shut down
D/jdwp ( 2718): JDWP shutting down net...
I/dalvikvm( 2718): Debugger has detached; object registry had 1 entries
D/dalvikvm( 2718): VM cleaning up
D/dalvikvm( 2718): LinearAlloc 0x0 used 623916 of 5242880 (11%)
D/ActivityManager( 52): Uninstalling process com.notification
I/dalvikvm( 2718): JNI: AttachCurrentThread (from ???.???)
E/AndroidRuntime( 2718): ERROR: thread attach failed
W/ResourceType( 52): Resources don't contain package for resource number 0x7f0
700e5
W/ResourceType( 52): Resources don't contain package for resource number 0x7f0
20031
W/ResourceType( 52): Resources don't contain package for resource number 0x7f0
20030
W/ResourceType( 52): Resources don't contain package for resource number 0x7f0
50000
W/ResourceType( 52): Resources don't contain package for resource number 0x7f0
60000
W/ResourceType( 52): Resources don't contain package for resource number 0x7f0
60001
D/dalvikvm( 1152): GC freed 139 objects / 5928 bytes in 230ms
D/dalvikvm( 52): GC freed 14606 objects / 863536 bytes in 259ms
W/ResourceType( 52): Resources don't contain package for resource number 0x7f0
700e5
W/ResourceType( 52): Resources don't contain package for resource number 0x7f0
20031
W/ResourceType( 52): Resources don't contain package for resource number 0x7f0
20030
W/ResourceType( 52): Resources don't contain package for resource number 0x7f0
50000
D/dalvikvm( 52): GC freed 425 objects / 17320 bytes in 275ms
W/ResourceType( 52): Resources don't contain package for resource number 0x7f0
60000
W/ResourceType( 52): Resources don't contain package for resource number 0x7f0
60001
D/AndroidRuntime( 2729):
D/AndroidRuntime( 2729): >>>>>>>>>>>>>> AndroidRuntime START <<<<<<<<<<<<<<
D/AndroidRuntime( 2729): CheckJNI is ON
D/AndroidRuntime( 2729): --- registering native functions ---
D/ddm-heap( 2729): Got feature list request
I/ActivityManager( 52): Starting activity: Intent { act=android.intent.action.
MAIN cat=[android.intent.category.LAUNCHER] flg=0x10000000 cmp=com.notification/
.NotificationActivity }
I/ActivityManager( 52): Start proc com.notification for activity com.notificat
ion/.NotificationActivity: pid=2735 uid=10034 gids={3003}
D/AndroidRuntime( 2729): Shutting down VM
D/dalvikvm( 2729): DestroyJavaVM waiting for non-daemon threads to exit
D/dalvikvm( 2729): DestroyJavaVM shutting VM down
D/dalvikvm( 2729): HeapWorker thread shutting down
D/dalvikvm( 2729): HeapWorker thread has shut down
D/jdwp ( 2729): JDWP shutting down net...
I/dalvikvm( 2729): Debugger has detached; object registry had 1 entries
D/dalvikvm( 2729): VM cleaning up
E/AndroidRuntime( 2729): ERROR: thread attach failed
D/dalvikvm( 2729): LinearAlloc 0x0 used 639500 of 5242880 (12%)
D/dalvikvm( 30): GC freed 299 objects / 11576 bytes in 264ms
D/ddm-heap( 2735): Got feature list request
D/dalvikvm( 30): GC freed 57 objects / 2432 bytes in 160ms
D/dalvikvm( 30): GC freed 2 objects / 48 bytes in 360ms
I/ActivityManager( 52): Displayed activity com.notification/.NotificationActiv
ity: 1204 ms (total 1204 ms)
W/KeyCharacterMap( 2735): No keyboard for id 0
W/KeyCharacterMap( 2735): Using default keymap: /system/usr/keychars/qwerty.kcm.
bin
I/ActivityManager( 52): Starting activity: Intent { cmp=com.notification/.Bg (
has extras) }
I/ActivityManager( 52): Displayed activity com.notification/.Bg: 329 ms (total
329 ms)
D/dalvikvm( 1152): GC freed 2454 objects / 141000 bytes in 600ms
I/ActivityManager( 52): Starting activity: Intent { cmp=com.notification/.List
1 bnds=[0,152][480,248] }
W/ActivityManager( 52): startActivity called from non-Activity context; forcin
g Intent.FLAG_ACTIVITY_NEW_TASK for: Intent { cmp=com.notification/.List1 bnds=[
0,152][480,248] }
D/AndroidRuntime( 2735): Shutting down VM
W/dalvikvm( 2735): threadid=3: thread exiting with uncaught exception (group=0x4
001b188)
E/AndroidRuntime( 2735): Uncaught handler: thread main exiting due to uncaught e
xception
E/AndroidRuntime( 2735): java.lang.NullPointerException
E/AndroidRuntime( 2735): at android.widget.ArrayAdapter.createViewFromRes
ource(ArrayAdapter.java:355)
E/AndroidRuntime( 2735): at android.widget.ArrayAdapter.getView(ArrayAdap
ter.java:323)
E/AndroidRuntime( 2735): at android.widget.AbsListView.obtainView(AbsList
View.java:1256)
E/AndroidRuntime( 2735): at android.widget.ListView.measureHeightOfChildr
en(ListView.java:1147)
E/AndroidRuntime( 2735): at android.widget.ListView.onMeasure(ListView.ja
va:1060)
E/AndroidRuntime( 2735): at android.view.View.measure(View.java:7964)
E/AndroidRuntime( 2735): at android.widget.RelativeLayout.measureChild(Re
lativeLayout.java:554)
E/AndroidRuntime( 2735): at android.widget.RelativeLayout.onMeasure(Relat
iveLayout.java:377)
E/AndroidRuntime( 2735): at android.view.View.measure(View.java:7964)
E/AndroidRuntime( 2735): at android.view.ViewGroup.measureChildWithMargin
s(ViewGroup.java:3023)
E/AndroidRuntime( 2735): at android.widget.FrameLayout.onMeasure(FrameLay
out.java:245)
E/AndroidRuntime( 2735): at android.view.View.measure(View.java:7964)
E/AndroidRuntime( 2735): at android.widget.LinearLayout.measureVertical(L
inearLayout.java:464)
E/AndroidRuntime( 2735): at android.widget.LinearLayout.onMeasure(LinearL
ayout.java:278)
E/AndroidRuntime( 2735): at android.view.View.measure(View.java:7964)
E/AndroidRuntime( 2735): at android.view.ViewGroup.measureChildWithMargin
s(ViewGroup.java:3023)
E/AndroidRuntime( 2735): at android.widget.FrameLayout.onMeasure(FrameLay
out.java:245)
E/AndroidRuntime( 2735): at android.view.View.measure(View.java:7964)
E/AndroidRuntime( 2735): at android.view.ViewRoot.performTraversals(ViewR
oot.java:763)
E/AndroidRuntime( 2735): at android.view.ViewRoot.handleMessage(ViewRoot.
java:1633)
E/AndroidRuntime( 2735): at android.os.Handler.dispatchMessage(Handler.ja
va:99)
E/AndroidRuntime( 2735): at android.os.Looper.loop(Looper.java:123)
E/AndroidRuntime( 2735): at android.app.ActivityThread.main(ActivityThrea
d.java:4363)
E/AndroidRuntime( 2735): at java.lang.reflect.Method.invokeNative(Native
Method)
E/AndroidRuntime( 2735): at java.lang.reflect.Method.invoke(Method.java:5
21)
E/AndroidRuntime( 2735): at com.android.internal.os.ZygoteInit$MethodAndA
rgsCaller.run(ZygoteInit.java:860)
E/AndroidRuntime( 2735): at com.android.internal.os.ZygoteInit.main(Zygot
eInit.java:618)
E/AndroidRuntime( 2735): at dalvik.system.NativeStart.main(Native Method)
I/Process ( 52): Sending signal. PID: 2735 SIG: 3
I/dalvikvm( 2735): threadid=7: reacting to signal 3
I/dalvikvm( 2735): Wrote stack trace to '/data/anr/traces.txt'
W/ActivityManager( 52): Launch timeout has expired, giving up wake lock!
W/ActivityManager( 52): Activity idle timeout for HistoryRecord{44dcace0 com.n
otification/.List1}
I/Process ( 2735): Sending signal. PID: 2735 SIG: 9
I/ActivityManager( 52): Process com.notification (pid 2735) has died.
I/WindowManager( 52): WIN DEATH: Window{44d8db78 com.notification/com.notifica
tion.List1 paused=false}
I/UsageStats( 52): Unexpected resume of com.android.launcher while already res
umed in com.notification
I/ActivityManager( 52): Start proc com.notification for broadcast com.notifica
tion/.AlarmReceiver: pid=2745 uid=10034 gids={3003}
W/InputManagerService( 52): Window already focused, ignoring focus gain of: co
m.android.internal.view.IInputMethodClient$Stub$Proxy@44f2e3d8
E/gralloc ( 52): [unregister] handle 0x423290 still locked (state=40000001)
D/ddm-heap( 2745): Got feature list request
D/dalvikvm( 1152): GC freed 212 objects / 9560 bytes in 82ms
I/ActivityManager( 52): Starting activity: Intent { act=android.intent.action.
MAIN cat=[android.intent.category.LAUNCHER] flg=0x10200000 cmp=com.notification/
.NotificationActivity }
I/ActivityManager( 52): Starting activity: Intent { cmp=com.notification/.Back
ground }
I/ActivityManager( 52): Displayed activity com.notification/.Background: 240 m
s (total 16387 ms)
D/dalvikvm( 234): GC freed 43 objects / 2024 bytes in 152ms