Question

好的，请帮助我，我尝试了我在网上找到的所有内容，但仍然会收到此错误。我已在资源文件夹中导入预先填充的只读sqlite数据库，包含100行，列为_ID，QUESTION，ANSWER，OPTION1，OPTION2，OPTION3。我在这个数据库中有3个具有相同结构的表。我从数据库中抽取随机问题，如果用户回答正确我再向他问两个额外的问题，而不是随机问题，但问题将与第一个问题的ID相同，但是来自表2.例如：我要猜猜标志有4个可能的答案，如果答案是正确的，那么我使用那个问题ID并向他询问城市表中的问题“什么是......的资本”，如果这是正确的，我会从货币表中问他“什么是在...中使用的货币“使用相同的ID。所以，这是崩溃报告：

java.lang.NullPointerException: println needs a message
at android.util.Log.println_native(Native Method)
at android.util.Log.e(Log.java:293)
at rs.androidaplikacije.zastaveigradovi.Kviz20Hard.nextQuestionGrad(Kviz20Hard.java:378)
at rs.androidaplikacije.zastaveigradovi.Kviz20Hard.access$1(Kviz20Hard.java:321)
at rs.androidaplikacije.zastaveigradovi.Kviz20Hard$2.run(Kviz20Hard.java:69)
at android.os.Handler.handleCallback(Handler.java:587)
at android.os.Handler.dispatchMessage(Handler.java:92)
at android.os.Looper.loop(Looper.java:130)
at android.app.ActivityThread.main(ActivityThread.java:3744)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:507)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:860)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:618)
at dalvik.system.NativeStart.main(Native Method)

这是游戏类，它的一部分，我得到错误的方法：

private void nextQuestionCities() {

         flag.setVisibility(View.GONE);
         dodatnoPitanje.setVisibility(View.VISIBLE);

         TestAdapter mDbHelper = new TestAdapter(this);
            DataBaseHelper myDbHelper = new DataBaseHelper(this);

            if(!myDbHelper.checkDataBase()){
            mDbHelper.createDatabase();
            }

            try{  

                mDbHelper.open(); 

                Cursor c = mDbHelper.getTestDataGradovi(mCurrentID);
                if (c != null) {
                       if (c.moveToFirst()) {

                List<Answer> labels = new ArrayList<Answer>();



                labels.add(new Answer(c.getString(2), true));
                labels.add(new Answer(c.getString(3), false));
                labels.add(new Answer(c.getString(4), false));
                labels.add(new Answer(c.getString(5), false));

                tacanOdg = c.getString(2);

                Collections.shuffle(labels);

                dodatnoPitanje.setText(c.getString(1));

                bOdgovor1.setText(labels.get(0).option);
                bOdgovor1.setTag(labels.get(0));
                bOdgovor1.setOnClickListener(clickListenerGrad);

                bOdgovor2.setText(labels.get(1).option);
                bOdgovor2.setTag(labels.get(1));
                bOdgovor2.setOnClickListener(clickListenerGrad);

                bOdgovor3.setText(labels.get(2).option);
                bOdgovor3.setTag(labels.get(2));
                bOdgovor3.setOnClickListener(clickListenerGrad);

                bOdgovor4.setText(labels.get(3).option);
                bOdgovor4.setTag(labels.get(3));
                bOdgovor4.setOnClickListener(clickListenerGrad);

                score.setText("Score: " + brojacTacnihOdgovora);

                       }
                       else {
                           Log.e("empty cursor", null);
                       }
                    }
                    else {
                        Log.e("null cursor", null);
                    }

            }
            finally{   
                mDbHelper.close();
            }
     }

错误在线：

Log.e("empty cursor", null);

这是我的适配器类：

public class TestAdapter 
{
    protected static final String TAG = "DataAdapter";

    private final Context mContext;
    private SQLiteDatabase mDb;
    private DataBaseHelper mDbHelper;

    public TestAdapter(Context context) 
    {
        this.mContext = context;
        mDbHelper = new DataBaseHelper(mContext);
    }

    public TestAdapter createDatabase() throws SQLException 
    {
        try 
        {
            mDbHelper.createDataBase();
        } 
        catch (IOException mIOException) 
        {
            Log.e(TAG, mIOException.toString() + "  UnableToCreateDatabase");
            throw new Error("UnableToCreateDatabase");
        }
        return this;
    }

    public TestAdapter open() throws SQLException 
    {
        try 
        {
            mDbHelper.openDataBase();
            mDbHelper.close();
            mDb = mDbHelper.getReadableDatabase();
        } 
        catch (SQLException mSQLException) 
        {
            Log.e(TAG, "open >>"+ mSQLException.toString());
            throw mSQLException;
        }
        return this;
    }

    public void close() 
    {
        mDbHelper.close();
    }

     public Cursor getTestData(String whereClause){
             String sql ="SELECT * FROM tblPitanja WHERE 1 = 1 " + whereClause + " ORDER BY RANDOM() LIMIT 1";
             return mDb.rawQuery(sql, null);
         }

     public Cursor getTestDataGradovi(long id){
            String sql ="SELECT * FROM tblGradovi WHERE _ID = " + id;
            return  mDb.rawQuery(sql, null);
        }

     public Cursor getTestDataValute(long id){
             String sql ="SELECT * FROM tblValute WHERE _ID = " + id;
             return mDb.rawQuery(sql, null);
         }

}

Answer 1

为此调用Log.e时更改：

Log.e("empty cursor", "");
Log.e("null cursor", "");

问题似乎是你向方法发送null并且他不接受null ...

android.util.Log.println_native中的java.lang.NullPointerException

1 个答案: