警报对话框中的错误

listview.setOnItemLongClickListener方法的“返回视图”中存在错误。该错误表示无法从具有无效结果类型的方法返回值。我正在尝试创建一个警告对话框，它将通知用户是否要删除。警报对话框中的错误

package com.example.user.swen; 


import android.app.AlertDialog; 
import android.app.ListActivity; 
import android.content.Context; 
import android.content.DialogInterface; 
import android.content.Intent; 
import android.os.Bundle; 
import android.text.Html; 
import android.view.LayoutInflater; 
import android.view.View; 
import android.view.ViewGroup; 
import android.widget.AdapterView; 
import android.widget.ArrayAdapter; 
import android.widget.Button; 
import android.widget.ListView; 
import android.widget.Toast; 


import java.util.ArrayList; 
import java.util.List; 



import com.example.user.swen.DB.RecordsDataSource; 
import com.example.user.swen.Model.Records; 

public class Record extends ListActivity { 

    public Button NewButton; 
    public RecordsDataSource Recordsdatasource; 
    ArrayAdapter<Records> RecordAdapter; 
    List<Records> records; 
    ListView listview; 
    Records selectedRecord; 


    @Override 
    protected void onCreate(Bundle savedInstanceState) { 
     super.onCreate(savedInstanceState); 
     setContentView(R.layout.activity_record); 
     Addrecords(); 


     //Referencing the Database 
     Recordsdatasource = new RecordsDataSource(this); 
     Recordsdatasource.open(); 

     LayoutInflater inflater = LayoutInflater.from(Record.this); 
     View view = inflater.inflate(R.layout.activity_record, null); 

     //set the listView to use the custom List Adapter 
     records = (List<Records>) Recordsdatasource.getAll(); 
     RecordAdapter = new RecordAdapter(this, 0, (ArrayList<Records>) records); 
     listview = (ListView) findViewById(android.R.id.list); 
     listview.setAdapter(RecordAdapter); 


     listview.setOnItemClickListener(new AdapterView.OnItemClickListener() { 
      @Override 
      public void onItemClick(AdapterView<?> parent, View view, int position, long id) { 
       selectedRecord = records.get(position); 
       AlertDialog.Builder a_builder = new AlertDialog.Builder(Record.this); 
       a_builder.setMessage("Duty: " + selectedRecord.getType()) 
         .setCancelable(false) 
         .setPositiveButton("Ok", new DialogInterface.OnClickListener() { 
          @Override 
          public void onClick(DialogInterface dialog, int which) { 
          } 
         }); 
       AlertDialog alert = a_builder.create(); 
       alert.setTitle(Html.fromHtml("<font color='#08ae9e'>Information</font>")); 
       alert.show(); 


      } 
     }); 


     listview.setOnItemLongClickListener(new AdapterView.OnItemLongClickListener() { 
      @Override 
      public boolean onItemLongClick(AdapterView<?> parent, View view, int position, long id) { 

       selectedRecord = records.get(position); 
       AlertDialog.Builder a_builder = new AlertDialog.Builder(Record.this); 
       a_builder.setMessage("Are you sure you want to delete?") 
         .setCancelable(false) 
         .setPositiveButton("Yes", new DialogInterface.OnClickListener() { 
          @Override 
          public void onClick(DialogInterface dialog, int which) { 
           deleteItem(selectedRecord); 
          } 
         }) 
         .setNegativeButton("No", new DialogInterface.OnClickListener() { 
          @Override 
          public void onClick(DialogInterface dialog, int which) { 
           dialog.cancel(); 
          } 
         }); 
       AlertDialog alert = a_builder.create(); 
       alert.setTitle(Html.fromHtml("<font color='#08ae9e'>Alert!!</font>")); 
       alert.show(); 
       return true; 
      } 
     }); 
     return view; 
    } 


    public void Addrecords() { 
     NewButton = (Button) findViewById(R.id.NewButton); 
     NewButton.setOnClickListener(new View.OnClickListener() { 

      @Override 
      public void onClick(View v) { 
       Intent addrecords = new Intent(Record.this, NewRecord.class); 
       startActivity(addrecords); 
      } 
     }); 
    } 


    public static void showToast(Context context, String text) { 
     Toast.makeText(context, text, Toast.LENGTH_LONG).show(); 
    } 

    private void deleteItem(Records selectedRecord) { 
     Recordsdatasource.removeRecords(selectedRecord); 
     showToast(this, "Usage deleted"); 
     RecordAdapter.notifyDataSetChanged(); 
     RecordAdapter.notifyDataSetInvalidated(); 
     refreshDisplay(); 
    } 


    private void refreshDisplay() { 
     records = Recordsdatasource.getAll(); 
     RecordAdapter.clear(); 
     RecordAdapter.addAll(records); 
    } 




}

来源

2016-06-08 user4535921

呼叫return view实际上位于onCreate。函数onCreate被声明为不返回（void）。因此，您无法返回View的实例。您只需删除该行或将其替换为return;而且，onItemLongClick必须返回boolean。所以你不能在那里移动return view。

来源

2016-06-08 14:32:49 Sunshinator

您正试图从您的活动的onCreate()方法返回视图。

@Override 
protected void onCreate(Bundle savedInstanceState) { 

    LayoutInflater inflater = LayoutInflater.from(Record.this); 
    View view = inflater.inflate(R.layout.activity_record, null); 

    //... 

    return view; 
}

正如你所看到的，onCreate()在活动中有一个void返回类型，这意味着你不应该在这个方法返回任何东西。

从代码的外观来看，您试图将此布局用作Activity的布局，但是您将View通胀代码与Fragment的onCreateView()方法中使用的代码混淆在一起，这确实需要您返回View。

在活动中，您需要拨打setContentView()来设置布局。您可以通过setContentView(R.layout.activity_record)使用资源ID设置布局，或者如果您想自己膨胀视图，则可以拨打setContentView(view)。

来源

2016-06-08 14:33:21

警报对话框中的错误

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