我正在尝试为我的listview创建一个删除功能，但有一些问题，我无法找到，甚至我发现logcat中的问题，我不知道问题在哪里，因为问题是指针在一行在其他活动中运行正常。请帮助我，并提前感谢：）
以下是错误指向：
**07-10 14:49:48.705 25554-25554/com.fingervoiz.app.tamla E/AndroidRuntime: FATAL EXCEPTION: main
Process: com.fingervoiz.app.tamla, PID: 25554
java.lang.NullPointerException: Attempt to read from field 'android.widget.TextView com.fingervoiz.app.tamla.Adapter.ListDIDadapter$Holder.txtFname' on a null object reference
at com.fingervoiz.app.tamla.Adapter.ListDIDadapter.getView(ListDIDadapter.java:61)**
at android.widget.AbsListView.obtainView(AbsListView.java:2467)
at android.widget.ListView.makeAndAddView(ListView.java:1894)
at android.widget.ListView.fillSpecific(ListView.java:1360)
at android.widget.ListView.layoutChildren(ListView.java:1673)
at android.widget.AbsListView.onLayout(AbsListView.java:2230)
at android.view.View.layout(View.java:16001)
at android.view.ViewGroup.layout(ViewGroup.java:5181)
at android.widget.LinearLayout.setChildFrame(LinearLayout.java:1959)
at android.widget.LinearLayout.layoutVertical(LinearLayout.java:1813)
at android.widget.LinearLayout.onLayout(LinearLayout.java:1722)
at android.view.View.layout(View.java:16001)
at android.view.ViewGroup.layout(ViewGroup.java:5181)
at android.widget.FrameLayout.layoutChildren(FrameLayout.java:639)
at android.widget.FrameLayout.onLayout(FrameLayout.java:574)
at android.view.View.layout(View.java:16001)
at android.view.ViewGroup.layout(ViewGroup.java:5181)
at android.widget.LinearLayout.setChildFrame(LinearLayout.java:1959)
at android.widget.LinearLayout.layoutVertical(LinearLayout.java:1813)
at android.widget.LinearLayout.onLayout(LinearLayout.java:1722)
at android.view.View.layout(View.java:16001)
at android.view.ViewGroup.layout(ViewGroup.java:5181)
at android.widget.FrameLayout.layoutChildren(FrameLayout.java:639)
at android.widget.FrameLayout.onLayout(FrameLayout.java:574)
at android.view.View.layout(View.java:16001)
at android.view.ViewGroup.layout(ViewGroup.java:5181)
at android.view.ViewRootImpl.performLayout(ViewRootImpl.java:2492)
at android.view.ViewRootImpl.performTraversals(ViewRootImpl.java:2189)
at android.view.ViewRootImpl.doTraversal(ViewRootImpl.java:1301)
at android.view.ViewRootImpl$TraversalRunnable.run(ViewRootImpl.java:6673)
at android.view.Choreographer$CallbackRecord.run(Choreographer.java:800)
at android.view.Choreographer.doCallbacks(Choreographer.java:603)
at android.view.Choreographer.doFrame(Choreographer.java:572)
at android.view.Choreographer$FrameDisplayEventReceiver.run(Choreographer.java:786)
at android.os.Handler.handleCallback(Handler.java:815)
at android.os.Handler.dispatchMessage(Handler.java:104)
at android.os.Looper.loop(Looper.java:194)
at android.app.ActivityThread.main(ActivityThread.java:5637)
at java.lang.reflect.Method.invoke(Native Method)
at java.lang.reflect.Method.invoke(Method.java:372)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:959)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:754)
我在listview适配器中的代码
public class ListDIDadapter extends ArrayAdapter<TamlaDataIdntModel> {
Context context;
int layoutResourceId;
ArrayList<TamlaDataIdntModel> data = new ArrayList<TamlaDataIdntModel>();
public ListDIDadapter (Context context,int layoutResourceId,ArrayList<TamlaDataIdntModel> data){
super(context,layoutResourceId,data);
this.layoutResourceId = layoutResourceId;
this.context = context;
this.data = data;
}
@Override
public View getView(int position, View convertView, ViewGroup parent) {
View view = convertView;
Holder holder;
if (view == null){
LayoutInflater inflater = ((Activity)context).getLayoutInflater();
view = inflater.inflate(layoutResourceId,parent,false);
holder = new Holder();
holder.txtFname = (TextView) view.findViewById(R.id.did_item_fname);
holder.txtMname = (TextView) view.findViewById(R.id.did_item_mname);
holder.txtLname = (TextView) view.findViewById(R.id.did_item_lname);
holder.txtGender = (TextView) view.findViewById(R.id.did_item_gender);
holder.txtBplace = (TextView) view.findViewById(R.id.did_item_bplace);
holder.txtBday = (TextView) view.findViewById(R.id.did_item_bday);
holder.txtAddress = (TextView) view.findViewById(R.id.did_item_address);
holder.imgProfile = (CircleImageView) view.findViewById(R.id.did_item_profilepic);
}else {
holder = (Holder) view.getTag();
}
//Feed Data
TamlaDataIdntModel dids = data.get(position);
holder.txtFname.setText("GIVEN NAME: "+dids.get_fname());
holder.txtMname.setText("MIDDLE NAME: "+dids.get_mname());
holder.txtLname.setText("FAMILY NAME: "+dids.get_lname());
holder.txtGender.setText("Gender: "+dids.get_gender());
holder.txtBplace.setText("Place of Birth: "+dids.get_bplace());
holder.txtBday.setText("Birthday: "+dids.get_bday());
holder.txtAddress.setText("Address: "+dids.get_address());
byte[] outImage = dids.get_dp();
ByteArrayInputStream imageStream = new ByteArrayInputStream(outImage);
Bitmap theImage = BitmapFactory.decodeStream(imageStream);
holder.imgProfile.setImageBitmap(theImage);
return view;
}
static class Holder{
CircleImageView imgProfile;
TextView txtFname,txtMname,txtLname,txtGender,txtBplace,txtBday,txtAddress;
}
}
代码
/*DELETE DATA IDENTITY*/
public void deleteDID(long id){
SQLiteDatabase db = this.mDBHelper.getWritableDatabase();
db.delete(TamlaDatabaseHelper.TABLE_DATAIDNT,TamlaDatabaseHelper.COLUMN_DI_ID + " = ?",
new String[]{String.valueOf(id)});
db.close();
}
，这是ListView活动
public class ListDataIdntActivity extends Activity{
ArrayList<TamlaDataIdntModel> imgArray = new ArrayList<TamlaDataIdntModel>();
ListDIDadapter adapter;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_list_did);
DataIdntDAO db = new DataIdntDAO(this);
List<TamlaDataIdntModel> inData = db.getAllDID();
for (TamlaDataIdntModel cn : inData){
imgArray.add(cn);
}
/*BACK BUTTON*/
Button back = (Button)findViewById(R.id.back_list_did);
back.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
Intent intent = new Intent(getApplicationContext(),MainActivity.class);
startActivity(intent);
finish();
}
});
/*LIST ADAPTER*/
adapter = new ListDIDadapter(this,R.layout.list_item_did_details,imgArray);
final ListView dataList = (ListView) findViewById(R.id.list_did);
dataList.setAdapter(adapter);
/*LIST ADAPTER ITEM LONG CLICK*/
dataList.setOnItemLongClickListener(new AdapterView.OnItemLongClickListener() {
@Override
public boolean onItemLongClick(AdapterView<?> parent, View view, final int position, long id) {
final TamlaDataIdntModel num = (TamlaDataIdntModel) parent.getItemAtPosition(position);
final CharSequence[] items = {"EDIT","DELETE","CANCEL"};
AlertDialog.Builder builder = new AlertDialog.Builder(ListDataIdntActivity.this);
builder.setTitle("YOUR CHOICE");
builder.setItems(items, new DialogInterface.OnClickListener() {
@Override
public void onClick(DialogInterface dialog, int item) {
if (items[item].equals("EDIT")) {
/*Intent pass = new Intent(ListDataIdntActivity.this, UserEdit.class);
pass.putExtra("Edit_Ses", idd);
startActivity(pass);*/
} else if (items[item].equals("DELETE")) {
DataIdntDAO db = new DataIdntDAO(ListDataIdntActivity.this);
db.deleteDID(position);
adapter.notifyDataSetChanged();
} else if (items[item].equals("CANCEL")) {
dialog.dismiss();
}
}
});
builder.show();
return true;
}
});
}
}
答案 0 :(得分：11)
ListDIDadapter $ Holder.txtFname＆＃39;在空对象引用上
由于这一行
holder = (Holder) view.getTag();
view.getTag()返回null，因为view.setTag(holder)未调用if-block