在将数据提取到Fragment时进行NPE

时间：2014-03-31 05:16:22

标签： android list android-fragments android-sqlite

我正在尝试从数据库中获取名称并在List中显示结果。但我得到Null Pointer Exception。我使用自定义的ArrayAdapter在List中显示名称。

FragmentGroups.java： - 

package com.sunmobile.navigationdrawer;
import java.util.ArrayList;
import java.util.List;

import android.app.Fragment;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.os.Bundle;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.view.View.OnClickListener;
import android.widget.ArrayAdapter;
import android.widget.Button;
import android.widget.ListAdapter;
import android.widget.ListView;
import android.widget.TextView;


import com.sunmobileappnow.mobileappnow.R;

public class FragmentGroups extends Fragment {

     SendJobDataBase db; 
     Cursor cursor;
     ArrayList<member> membr;
     ListView list1 ;
     ListView list2 ;
     Button group1;
     Button group2;
     GroupAdapter groupadapter;


    public FragmentGroups(){}

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
            Bundle savedInstanceState) {

        View rootView = inflater.inflate(R.layout.group_fragment, container, false);

        group1 = (Button) rootView.findViewById(R.id.Gp1);
        group2 = (Button) rootView.findViewById(R.id.Gp2);


    list1 = (ListView) rootView.findViewById(R.id.list1);

       membr=getMembersList();  

        groupadapter= new GroupAdapter(this.getActivity(),R.layout.listrow_item ,membr);
        list1.setAdapter((ListAdapter) groupadapter);   


String[] values2 = new String[] { "Cricket", 
    "Hockey",
    "footBall",
    "BasketBall", 
    "Soccer", 
    "Badminton", 
    "Tennis", 

   };

   list2 = (ListView) rootView.findViewById(R.id.list2);

     ArrayAdapter<String> adapter2 = new ArrayAdapter<String> (this.getActivity(),R.layout.listrow, values2);
     list2.setAdapter(adapter2);  



      group1.setOnClickListener(new OnClickListener() {

    @Override
       public void onClick(View v) {

        list1.setVisibility(View.VISIBLE);
        list2.setVisibility(View.INVISIBLE);

    }
});


group2.setOnClickListener(new OnClickListener() {

    @Override
    public void onClick(View v) {

        list1.setVisibility(View.GONE);
        list2.setVisibility(View.VISIBLE);

    }
});
return rootView;

    }       

    public ArrayList<member> getMembersList() {
        ArrayList<member> user = new ArrayList<member>();

        String selectQuery = "SELECT sename FROM jobsend" ;
        this.db = new SendJobDataBase(getActivity());
        this.db.getWritableDatabase();
         cursor = db.rawQuery(selectQuery, null);

        if (cursor.moveToFirst()) {
            do {
            member contact = new member();

          contact.setName(cursor.getString(1));
          user.add(contact);
        } while (cursor.moveToNext());
    }
    return user;

    } 

}

SendJobDataBase.java： - 

package com.sunmobile.navigationdrawer;

import android.content.Context;
import android.database.Cursor;
import android.database.SQLException;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteOpenHelper;
import android.database.sqlite.SQLiteStatement;
import java.util.ArrayList;
import java.util.List;



public class SendJobDataBase
{
    private static final  String DATABASE_NAME = "myjob.db";
    private static final int DATABASE_VERSION = 2;
    static final String TABLE_NAME = "jobsend";
    private static Context context;
    static SQLiteDatabase db;
   Cursor cursor;

    private SQLiteStatement insertStmt;

    private static final String INSERT = "insert into " + TABLE_NAME + " (sename,smobno,spicktime,spickaddr,sfair,ssendjob) values (?,?,?,?,?,?)";
    protected static final String enternpw = null;
    public SendJobDataBase(Context context) {
    SendJobDataBase.context = context;
    OpenHelper openHelper = new OpenHelper(SendJobDataBase.context);
    SendJobDataBase.db = openHelper.getWritableDatabase();
    this.insertStmt = SendJobDataBase.db.compileStatement(INSERT);
    }
    public long insert(String sename,String smobno,String spicktime,String spickaddr,String sfair,String ssendjob) {
    this.insertStmt.bindString(1, sename);
    this.insertStmt.bindString(2, smobno);
    this.insertStmt.bindString(3, spicktime);
    this.insertStmt.bindString(4, spickaddr);
    this.insertStmt.bindString(5, sfair);
    this.insertStmt.bindString(6, ssendjob);
    return this.insertStmt.executeInsert();
    }

    public void deleteAll() {
    db.delete(TABLE_NAME, null, null);
    }

    public List<String[]> selectAll()
    {
    List<String[]> list = new ArrayList<String[]>();
    Cursor cursor = db.query(TABLE_NAME, new String[] { "id","sename","smobno","spicktime","spickaddr","sfair","ssendjob" }, null, null, null, null, "sename asc");
    int x=0;
    if (cursor.moveToFirst()) {
       do {
        String[] b1=new String[]{cursor.getString(0),cursor.getString(1),cursor.getString(2),
                cursor.getString(3),cursor.getString(4),cursor.getString(5),
                cursor.getString(6)};
        list.add(b1);
        x=x+1;
       } while (cursor.moveToNext());
    }
    if (cursor != null && !cursor.isClosed()) {
       cursor.close();
    }
    cursor.close();
    return list;
   }

   public void delete(int rowId) {
    db.delete(TABLE_NAME, null, null);
   }

   private static class OpenHelper extends SQLiteOpenHelper {
    OpenHelper(Context context) {
         super(context, DATABASE_NAME, null, DATABASE_VERSION);
    }
    @Override
    public void onCreate(SQLiteDatabase db) {
         db.execSQL("CREATE TABLE " + TABLE_NAME + " (id INTEGER PRIMARY KEY, sename TEXT, smobno TEXT,spicktime TEXT,spickaddr TEXT, sfair TEXT,ssendjob TEXT)");
    }

    @Override
    public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion)
        {
         db.execSQL("DROP TABLE IF EXISTS " + TABLE_NAME);
         onCreate(db);
    }
   }


public Cursor rawQuery(String selectQuery, Object object) {
    // TODO Auto-generated method stub
    return cursor;
}
public static SendJobDataBase getDBAdapterInstance(FragmentGroups viewPassword) {
    // TODO Auto-generated method stub
    return null;
}
public Object getenternpw() {
    // TODO Auto-generated method stub
    return null;
}
public static Cursor getSinlgeEntry() {
    // TODO Auto-generated method stub

    Cursor cur =db.rawQuery("SELECT * FROM "+  TABLE_NAME, null);
    // colName1+"='"+name+"'" ->  wherclause
    System.out.println("Record count are "+cur.getCount());
    return cur; 

}



public static void close() {
    // TODO Auto-generated method stub

}
public SendJobDataBase open() {
    // TODO Auto-generated method stub
    return null;
}
public SendJobDataBase getWritableDatabase() {
    // TODO Auto-generated method stub
    return null;
}
}

错误： - 

03-31 01:54:00.891: E/AndroidRuntime(1086): FATAL EXCEPTION: main
03-31 01:54:00.891: E/AndroidRuntime(1086): Process: com.sunmobileappnow.mobileappnow, PID: 1086
03-31 01:54:00.891: E/AndroidRuntime(1086): java.lang.NullPointerException
03-31 01:54:00.891: E/AndroidRuntime(1086):     at com.sunmobile.navigationdrawer.FragmentGroups.getMembersList(FragmentGroups.java:105)
03-31 01:54:00.891: E/AndroidRuntime(1086):     at com.sunmobile.navigationdrawer.FragmentGroups.onCreateView(FragmentGroups.java:48)
03-31 01:54:00.891: E/AndroidRuntime(1086):     at android.app.Fragment.performCreateView(Fragment.java:1700)
03-31 01:54:00.891: E/AndroidRuntime(1086):     at android.app.FragmentManagerImpl.moveToState(FragmentManager.java:890)
03-31 01:54:00.891: E/AndroidRuntime(1086):     at android.app.FragmentManagerImpl.moveToState(FragmentManager.java:1062)
03-31 01:54:00.891: E/AndroidRuntime(1086):     at android.app.BackStackRecord.run(BackStackRecord.java:684)
03-31 01:54:00.891: E/AndroidRuntime(1086):     at android.app.FragmentManagerImpl.execPendingActions(FragmentManager.java:1447)
03-31 01:54:00.891: E/AndroidRuntime(1086):     at android.app.FragmentManagerImpl$1.run(FragmentManager.java:443)
03-31 01:54:00.891: E/AndroidRuntime(1086):     at android.os.Handler.handleCallback(Handler.java:733)
03-31 01:54:00.891: E/AndroidRuntime(1086):     at android.os.Handler.dispatchMessage(Handler.java:95)
03-31 01:54:00.891: E/AndroidRuntime(1086):     at android.os.Looper.loop(Looper.java:137)
03-31 01:54:00.891: E/AndroidRuntime(1086):     at android.app.ActivityThread.main(ActivityThread.java:4998)
03-31 01:54:00.891: E/AndroidRuntime(1086):     at java.lang.reflect.Method.invokeNative(Native Method)
03-31 01:54:00.891: E/AndroidRuntime(1086):     at java.lang.reflect.Method.invoke(Method.java:515)
03-31 01:54:00.891: E/AndroidRuntime(1086):     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:777)
03-31 01:54:00.891: E/AndroidRuntime(1086):     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:593)
03-31 01:54:00.891: E/AndroidRuntime(1086):     at dalvik.system.NativeStart.main(Native Method)

1 个答案:

答案 0 :(得分：0)

对于来自logcat的错误，
在getMembersList()，cursor让你成为NPE，你可以这样验证：

之前

if (cursor.moveToFirst()) {

检查：

if(cursor != null && cursor.getCount() > 0)

此外，您可以/需要为全局变量membr的结果操作设置为null，该数据作为数据传递给groupadapter

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