當我添加行list.add(sb.toString());
程序停止工作。
當我刪除它的數據加載到StringBuilder,但我無法顯示它。
我搜索了一個解決方案,但每個代碼示例都是一樣的。
我找不到問題。Android。當我嘗試將項目添加到ArrayList時,爲什麼會出現錯誤?
public ArrayList<String> list;
public ArrayAdapter<String> adapter;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_contact_list);
listView = (ListView) findViewById(R.id.contactList);
// listView.setOnItemClickListener(this);
Cursor phones = getContentResolver().query(
ContactsContract.CommonDataKinds.Phone.CONTENT_URI, null, null,
null, null);
while (phones.moveToNext()) {
String name = phones
.getString(phones
.getColumnIndex(ContactsContract.CommonDataKinds.Phone.DISPLAY_NAME));
String phoneNumber = phones
.getString(phones
.getColumnIndex(ContactsContract.CommonDataKinds.Phone.NUMBER));
StringBuilder sb = new StringBuilder();
sb.append(name).append(" ").append(phoneNumber);
list.add(sb.toString());
Log.d("Added:", sb.toString());
}
adapter = new ArrayAdapter<String>(this,
android.R.layout.simple_list_item_1, list);
listView.setAdapter(adapter);
phones.close();
堆棧跟蹤:
02-05 10:41:03.505: E/AndroidRuntime(29762): FATAL EXCEPTION: main
02-05 10:41:03.505: E/AndroidRuntime(29762): java.lang.NullPointerException
02-05 10:41:03.505: E/AndroidRuntime(29762): at com.example.anewapp.CameraPreview.surfaceCreated(CameraPreview.java:30)
02-05 10:41:03.505: E/AndroidRuntime(29762): at android.view.SurfaceView.updateWindow(SurfaceView.java:547)
02-05 10:41:03.505: E/AndroidRuntime(29762): at android.view.SurfaceView.access$000(SurfaceView.java:85)
02-05 10:41:03.505: E/AndroidRuntime(29762): at android.view.SurfaceView$3.onPreDraw(SurfaceView.java:173)
02-05 10:41:03.505: E/AndroidRuntime(29762): at android.view.ViewTreeObserver.dispatchOnPreDraw(ViewTreeObserver.java:671)
02-05 10:41:03.505: E/AndroidRuntime(29762): at android.view.ViewRootImpl.performTraversals(ViewRootImpl.java:1821)
02-05 10:41:03.505: E/AndroidRuntime(29762): at android.view.ViewRootImpl.doTraversal(ViewRootImpl.java:999)
02-05 10:41:03.505: E/AndroidRuntime(29762): at android.view.ViewRootImpl$TraversalRunnable.run(ViewRootImpl.java:4217)
02-05 10:41:03.505: E/AndroidRuntime(29762): at android.view.Choreographer$CallbackRecord.run(Choreographer.java:725)
02-05 10:41:03.505: E/AndroidRuntime(29762): at android.view.Choreographer.doCallbacks(Choreographer.java:555)
02-05 10:41:03.505: E/AndroidRuntime(29762): at android.view.Choreographer.doFrame(Choreographer.java:525)
02-05 10:41:03.505: E/AndroidRuntime(29762): at android.view.Choreographer$FrameDisplayEventReceiver.run(Choreographer.java:711)
02-05 10:41:03.505: E/AndroidRuntime(29762): at android.os.Handler.handleCallback(Handler.java:615)
02-05 10:41:03.505: E/AndroidRuntime(29762): at android.os.Handler.dispatchMessage(Handler.java:92)
02-05 10:41:03.505: E/AndroidRuntime(29762): at android.os.Looper.loop(Looper.java:137)
02-05 10:41:03.505: E/AndroidRuntime(29762): at android.app.ActivityThread.main(ActivityThread.java:4802)
02-05 10:41:03.505: E/AndroidRuntime(29762): at java.lang.reflect.Method.invokeNative(Native Method)
02-05 10:41:03.505: E/AndroidRuntime(29762): at java.lang.reflect.Method.invoke(Method.java:511)
02-05 10:41:03.505: E/AndroidRuntime(29762): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:813)
02-05 10:41:03.505: E/AndroidRuntime(29762): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:580)
02-05 10:41:03.505: E/AndroidRuntime(29762): at dalvik.system.NativeStart.main(Native Method)
這裏有一個nullpointerexception @ camerapreview.java第30行 – Raghunandan
你在哪裏使用了你的列表,即public ArrayList list,請寫list = new ArrayList ; afert line setContentView(R.layout.activity_contact_list); –
theLazyFinder
鹿neeni!你的解決方案几乎可行,但需要list = new ArrayList(); :D謝謝! –
user3270899