从sqlite到列表的空指针异常数据

Question

我正在列出分数列表，从数据库获取数据。

它给我的错误是： NullPointerException

这是我所做的：

活动：

public class ScoresActivity extends Activity {
    ScoreDataSource sds;
    ArrayList<Score>scores;
    ScoreAdapter adapter;
    ListView listview;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        listview=(ListView) findViewById(R.id.AllScores);
        sds=new ScoreDataSource(this);
        sds.open();
        scores=sds.getAllCustomers();
        if(scores.size()==0)
        {
             createCustomers();
             scores=sds.getAllCustomers();
        }
        adapter=new ScoreAdapter(this,R.layout.row,scores);
        listview.setAdapter(adapter);
    //  Customer c=cds.getCustomerById(1);
        //Log.i("getid","customer name is " + c.getFirstName());

    }


        @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        // Inflate the menu; this adds items to the action bar if it is present.
        getMenuInflater().inflate(R.menu.scores, menu);
        return true;
    }

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        // TODO Auto-generated method stub
        switch (item.getItemId()) {
        case R.id.menu_classic:
            scores=sds.getAllCustomersByFIlter("Game==Classic", "waste ASC");
            Log.i("filter", "list count is " + scores.size());
            refreshMyAdapter();
            break;
        case R.id.menu_vscomp :
            scores=sds.getAllCustomersByFIlter("Game==VScomp", "waste ASC");
            Log.i("filter", "list count is " + scores.size());
            refreshMyAdapter();
            break;
        case R.id.menu_allcustomers: 
            scores=sds.getAllCustomers();
            Log.i("filter", "list count is " + scores.size());
            refreshMyAdapter();
            break;
        default:
            break;
        }
        return super.onOptionsItemSelected(item);
    }
    @Override
    protected void onResume() {
        // TODO Auto-generated method stub
        super.onResume();
        sds.open();
    }
    @Override
    protected void onPause() {
        // TODO Auto-generated method stub
        super.onPause();
        sds.close();
    }
    public void createCustomers()
    {
        Score s1=new Score(0,"a","1",50,"Classic");
        s1=sds.createCustomer(s1);
        Score s2=new Score(0,"b","2",600,"Classic");
        s2=sds.createCustomer(s2);
        Score s3=new Score(0,"c","2",600,"VScomp");
        s3=sds.createCustomer(s3);

    }
    public void refreshMyAdapter()
    {
        adapter=new ScoreAdapter(this,R.layout.row,scores);
        listview.setAdapter(adapter);
    }
}

评分：

    public class ScoreDataSource {
    Context context;
    ScoreOpenHelper helper;
    SQLiteDatabase database;
    String []allColumns={ScoreOpenHelper.COLUMN_ID, ScoreOpenHelper.COLUMN_NAME,
            ScoreOpenHelper.COLUMN_DATE,ScoreOpenHelper.COLUMN_SCORE,ScoreOpenHelper.COLUMN_GAME};
    public ScoreDataSource(Context context)
    {
        this.context=context;
        helper=new ScoreOpenHelper(context);
    }
    public void open()
    {
        database=helper.getWritableDatabase();
        Log.i("data", "Database connection open");
    }
    public void close()
    {
        helper.close();
        Log.i("data", "Database connection close");
    }
    //quearies ...... 
    public Score createCustomer(Score s)
    {
        ContentValues values=new ContentValues();
        values.put(ScoreOpenHelper.COLUMN_NAME, s.getName());
        values.put(ScoreOpenHelper.COLUMN_DATE, s.getScore());
        values.put(ScoreOpenHelper.COLUMN_SCORE, s.getScore());
        values.put(ScoreOpenHelper.COLUMN_GAME, s.getGame());
        long insertId=database.insert(ScoreOpenHelper.TABLE_SCORES, null, values);
        Log.i("data", "Score " + insertId + "insert to database");
        s.setID(insertId);
        return s;

    }
    public ArrayList<Score>getAllCustomers()
    {
        Cursor cursor=database.query(ScoreOpenHelper.TABLE_SCORES, allColumns, null, null, null, null, null);
        ArrayList<Score>l=convertCurserToList(cursor);
        return  l;      
    }
    public ArrayList<Score>getAllCustomersByFIlter(String selection,String OrderBy)
    {
        Cursor cursor=database.query(ScoreOpenHelper.TABLE_SCORES, allColumns, selection, null, null, null, OrderBy);
        ArrayList<Score>l=convertCurserToList(cursor);
        return  l;      
    }

    private ArrayList<Score> convertCurserToList(Cursor cursor) {
        ArrayList<Score>l=new ArrayList<Score>();
        if(cursor.getCount()>0)
        {
            while(cursor.moveToNext())
            {
                long id=cursor.getLong(cursor.getColumnIndex(ScoreOpenHelper.COLUMN_ID));
                String name=cursor.getString(cursor.getColumnIndex(ScoreOpenHelper.COLUMN_NAME));
                String date=cursor.getString(cursor.getColumnIndex(ScoreOpenHelper.COLUMN_DATE));
                int  score=cursor.getInt(cursor.getColumnIndex(ScoreOpenHelper.COLUMN_SCORE));
                String game=cursor.getString(cursor.getColumnIndex(ScoreOpenHelper.COLUMN_GAME));
                Score c=new Score(id,name,date,score,game);
                l.add(c);
            }                   
        }
        return l;
    }
    public Score getCustomerById(long rowId)
    {
        Cursor cursor=database.query(ScoreOpenHelper.TABLE_SCORES, allColumns, ScoreOpenHelper.COLUMN_ID +  "=" + rowId,
                null, null, null, null);
        cursor.moveToFirst();
        if(cursor.getCount()>0)
        {
            long id=cursor.getLong(cursor.getColumnIndex(ScoreOpenHelper.COLUMN_ID));
            String name=cursor.getString(cursor.getColumnIndex(ScoreOpenHelper.COLUMN_NAME));
            String date=cursor.getString(cursor.getColumnIndex(ScoreOpenHelper.COLUMN_DATE));
            int  score=cursor.getInt(cursor.getColumnIndex(ScoreOpenHelper.COLUMN_SCORE));
            String game=cursor.getString(cursor.getColumnIndex(ScoreOpenHelper.COLUMN_GAME));
            Score c=new Score(id,name,date,score,game);
            return c;
        }
        return null;
    }
    public long deleteAll()
    {
        return  database.delete(ScoreOpenHelper.TABLE_SCORES, null, null);      
    }
    public long deleteCustomerByRow(long rowId)
    {
        return  database.delete(ScoreOpenHelper.TABLE_SCORES, ScoreOpenHelper.COLUMN_ID +"=" + rowId, null);        
    }
    public long updateByRow(Score c)
    {
        ContentValues values=new ContentValues();
        values.put(ScoreOpenHelper.COLUMN_ID, c.getID());
        values.put(ScoreOpenHelper.COLUMN_NAME, c.getName());
        values.put(ScoreOpenHelper.COLUMN_DATE, c.getDate());
        values.put(ScoreOpenHelper.COLUMN_SCORE, c.getScore());
        values.put(ScoreOpenHelper.COLUMN_GAME, c.getGame());
        return database.update(ScoreOpenHelper.TABLE_SCORES, values,ScoreOpenHelper.COLUMN_ID +"=" + c.getID(), null);
    }
}

sourceopenhelp：

    public class ScoreOpenHelper extends SQLiteOpenHelper {

    public static final String DATABASENAME="scoredb.db";
    public static final String TABLE_SCORES="scores";   
    public static final int DATABASEVERSION=2;
    public static final String COLUMN_ID="ID";
    public static final String COLUMN_NAME="Name";
    public static final String COLUMN_DATE="Date";
    public static final String COLUMN_SCORE="Score";
    public static final String COLUMN_GAME="Game";
    private static final String CREATE_TABLE_CUSTOMER="CREATE TABLE IF NOT EXISTS " + 
            TABLE_SCORES + "(" + COLUMN_ID +  " INTEGER PRIMARY KEY AUTOINCREMENT," + COLUMN_NAME + " VARCHAR," 
            + COLUMN_DATE + " VARCHAR,"+ COLUMN_SCORE + " INTEGER,"+ COLUMN_GAME +" VARCHAR"  +   ");";
    SQLiteDatabase database;
    public ScoreOpenHelper(Context context) {
        super(context, DATABASENAME, null, DATABASEVERSION);
        // TODO Auto-generated constructor stub
    }

    @Override
    public void onCreate(SQLiteDatabase db) {
        db.execSQL(CREATE_TABLE_CUSTOMER);
        Log.i("data", "Table customer created");
    }

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

得分制：

    public class ScoreAdapter extends ArrayAdapter<Score> {
    Context context;
    int layoutResourceId;
    ArrayList<Score>data;
    public ScoreAdapter(Context context, int textViewResourceId,
            List<Score> objects) {
        super(context, textViewResourceId, objects);
        this.context=context;
        this.layoutResourceId=textViewResourceId;
        this.data=(ArrayList<Score>) objects;
    }
    @Override
    public View getView(int position, View convertView, ViewGroup parent) {
        // TODO Auto-generated method stub
        View row;
        LayoutInflater inflater= ((Activity) context).getLayoutInflater();
        row=inflater.inflate(layoutResourceId, parent,false);
        Score s=data.get(position);
        TextView name=(TextView) row.findViewById(R.id.name);
        TextView date=(TextView) row.findViewById(R.id.date);
        TextView score=(TextView) row.findViewById(R.id.score);
        //Button btn=(Button) row.findViewById(R.id.btnDelete);

        name.setText(s.getName());
        date.setText(s.getDate());
        score.setText(s.getScore());
        return row;

    }
}

我尝试过几次，问一个朋友。没有任何帮助。如果您需要我添加菜单或row的XML或ListView告诉我的位置。

感谢您的帮助

编辑：

新的堆栈跟踪：

03-13 12:56:09.109: I/data(949): Database connection open
03-13 12:56:09.160: I/data(949): Database connection open
03-13 12:56:09.339: W/ResourceType(949): No package identifier when getting value for resource number 0x00000032
03-13 12:56:09.349: D/AndroidRuntime(949): Shutting down VM
03-13 12:56:09.349: W/dalvikvm(949): threadid=1: thread exiting with uncaught exception (group=0x40a71930)
03-13 12:56:09.499: E/AndroidRuntime(949): FATAL EXCEPTION: main
03-13 12:56:09.499: E/AndroidRuntime(949): android.content.res.Resources$NotFoundException: String resource ID #0x32
03-13 12:56:09.499: E/AndroidRuntime(949):  at android.content.res.Resources.getText(Resources.java:230)
03-13 12:56:09.499: E/AndroidRuntime(949):  at android.widget.TextView.setText(TextView.java:3769)
03-13 12:56:09.499: E/AndroidRuntime(949):  at com.example.snake.ScoreAdapter.getView(ScoreAdapter.java:43)
03-13 12:56:09.499: E/AndroidRuntime(949):  at android.widget.AbsListView.obtainView(AbsListView.java:2159)
03-13 12:56:09.499: E/AndroidRuntime(949):  at android.widget.ListView.measureHeightOfChildren(ListView.java:1246)
03-13 12:56:09.499: E/AndroidRuntime(949):  at android.widget.ListView.onMeasure(ListView.java:1158)
03-13 12:56:09.499: E/AndroidRuntime(949):  at android.view.View.measure(View.java:15518)
03-13 12:56:09.499: E/AndroidRuntime(949):  at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:4825)
03-13 12:56:09.499: E/AndroidRuntime(949):  at android.widget.LinearLayout.measureChildBeforeLayout(LinearLayout.java:1404)
03-13 12:56:09.499: E/AndroidRuntime(949):  at android.widget.LinearLayout.measureVertical(LinearLayout.java:695)
03-13 12:56:09.499: E/AndroidRuntime(949):  at android.widget.LinearLayout.onMeasure(LinearLayout.java:588)
03-13 12:56:09.499: E/AndroidRuntime(949):  at android.view.View.measure(View.java:15518)
03-13 12:56:09.499: E/AndroidRuntime(949):  at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:4825)
03-13 12:56:09.499: E/AndroidRuntime(949):  at android.widget.FrameLayout.onMeasure(FrameLayout.java:310)
03-13 12:56:09.499: E/AndroidRuntime(949):  at android.view.View.measure(View.java:15518)
03-13 12:56:09.499: E/AndroidRuntime(949):  at android.widget.LinearLayout.measureVertical(LinearLayout.java:847)
03-13 12:56:09.499: E/AndroidRuntime(949):  at android.widget.LinearLayout.onMeasure(LinearLayout.java:588)
03-13 12:56:09.499: E/AndroidRuntime(949):  at android.view.View.measure(View.java:15518)
03-13 12:56:09.499: E/AndroidRuntime(949):  at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:4825)
03-13 12:56:09.499: E/AndroidRuntime(949):  at android.widget.FrameLayout.onMeasure(FrameLayout.java:310)
03-13 12:56:09.499: E/AndroidRuntime(949):  at com.android.internal.policy.impl.PhoneWindow$DecorView.onMeasure(PhoneWindow.java:2176)
03-13 12:56:09.499: E/AndroidRuntime(949):  at android.view.View.measure(View.java:15518)
03-13 12:56:09.499: E/AndroidRuntime(949):  at android.view.ViewRootImpl.performMeasure(ViewRootImpl.java:1874)
03-13 12:56:09.499: E/AndroidRuntime(949):  at android.view.ViewRootImpl.measureHierarchy(ViewRootImpl.java:1089)
03-13 12:56:09.499: E/AndroidRuntime(949):  at android.view.ViewRootImpl.performTraversals(ViewRootImpl.java:1265)
03-13 12:56:09.499: E/AndroidRuntime(949):  at android.view.ViewRootImpl.doTraversal(ViewRootImpl.java:989)
03-13 12:56:09.499: E/AndroidRuntime(949):  at android.view.ViewRootImpl$TraversalRunnable.run(ViewRootImpl.java:4351)
03-13 12:56:09.499: E/AndroidRuntime(949):  at android.view.Choreographer$CallbackRecord.run(Choreographer.java:749)
03-13 12:56:09.499: E/AndroidRuntime(949):  at android.view.Choreographer.doCallbacks(Choreographer.java:562)
03-13 12:56:09.499: E/AndroidRuntime(949):  at android.view.Choreographer.doFrame(Choreographer.java:532)
03-13 12:56:09.499: E/AndroidRuntime(949):  at android.view.Choreographer$FrameDisplayEventReceiver.run(Choreographer.java:735)
03-13 12:56:09.499: E/AndroidRuntime(949):  at android.os.Handler.handleCallback(Handler.java:725)
03-13 12:56:09.499: E/AndroidRuntime(949):  at android.os.Handler.dispatchMessage(Handler.java:92)
03-13 12:56:09.499: E/AndroidRuntime(949):  at android.os.Looper.loop(Looper.java:137)
03-13 12:56:09.499: E/AndroidRuntime(949):  at android.app.ActivityThread.main(ActivityThread.java:5041)
03-13 12:56:09.499: E/AndroidRuntime(949):  at java.lang.reflect.Method.invokeNative(Native Method)
03-13 12:56:09.499: E/AndroidRuntime(949):  at java.lang.reflect.Method.invoke(Method.java:511)
03-13 12:56:09.499: E/AndroidRuntime(949):  at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:793)
03-13 12:56:09.499: E/AndroidRuntime(949):  at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:560)
03-13 12:56:09.499: E/AndroidRuntime(949):  at dalvik.system.NativeStart.main(Native Method)

Answer 1

由于NPE在listview.setAdapter(adapter)中，listview为null。它是null，因为findViewById(R.id.AllScores)返回null。它返回null，因为布局activity_main不包含具有此类ID的视图，或者资源ID和二进制XML文件不同步。在第一种情况下，将ListView添加到布局中。在后一种情况下，清洁并重建项目。

对于后续例外堆栈：

03-13 12:56:09.499: E/AndroidRuntime(949): android.content.res.Resources$NotFoundException: String resource ID #0x32
03-13 12:56:09.499: E/AndroidRuntime(949):  at android.content.res.Resources.getText(Resources.java:230)
03-13 12:56:09.499: E/AndroidRuntime(949):  at android.widget.TextView.setText(TextView.java:3769)
03-13 12:56:09.499: E/AndroidRuntime(949):  at com.example.snake.ScoreAdapter.getView(ScoreAdapter.java:43)

...在您的适配器getView()中，使用setText(String.valueOf(intValue))代替setText(intValue)，因此INT不被视为资源ID。（这可能是int的分数。）