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Asked: 2026-05-31T16:53:37+00:00

here’s the code(Where I think the NullPointerException is generated): public String getData(String s1,String s2,String

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here’s the code(Where I think the NullPointerException is generated):

public String getData(String s1,String s2,String s3,String s4){

        DatabaseHelper databaseHelper = new DatabaseHelper(this);
        SQLiteDatabase db = databaseHelper.getWritableDatabase();

        String columns[] = new String[]{"alphabet","st1","st2","st3","st4" };
        Cursor c = db.query("capitals", columns, null, null,null,null, null);
        String result = "";

        int calpha = c.getColumnIndex("alphabet");
        int cst1 = c.getColumnIndex("st1");
        int cst2 = c.getColumnIndex("st2");
        int cst3 = c.getColumnIndex("st3");
        int cst4 = c.getColumnIndex("st4");

        for(c.moveToFirst(); !c.isAfterLast(); c.moveToNext()){

            if(c.getString(cst1).equals(s1) && c.getString(cst2).equals(s2) && c.getString(cst3).equals(s3) && c.getString(cst4).equals(s4))
                result = c.getString(calpha);
            else
                result = null;

        }

        return result;
    }

Log content:

03-19 21:27:34.263: E/AndroidRuntime(26498): FATAL EXCEPTION: main
03-19 21:27:34.263: E/AndroidRuntime(26498): java.lang.NullPointerException
03-19 21:27:34.263: E/AndroidRuntime(26498):    at learn.myandroidapp.hr.HandwritingRecognitionCanvas.getData(HandwritingRecognitionCanvas.java:213)
03-19 21:27:34.263: E/AndroidRuntime(26498):    at learn.myandroidapp.hr.HandwritingRecognitionCanvas$1.onClick(HandwritingRecognitionCanvas.java:103)
03-19 21:27:34.263: E/AndroidRuntime(26498):    at android.view.View.performClick(View.java:3511)
03-19 21:27:34.263: E/AndroidRuntime(26498):    at android.view.View$PerformClick.run(View.java:14105)
03-19 21:27:34.263: E/AndroidRuntime(26498):    at android.os.Handler.handleCallback(Handler.java:605)
03-19 21:27:34.263: E/AndroidRuntime(26498):    at android.os.Handler.dispatchMessage(Handler.java:92)
03-19 21:27:34.263: E/AndroidRuntime(26498):    at android.os.Looper.loop(Looper.java:137)
03-19 21:27:34.263: E/AndroidRuntime(26498):    at android.app.ActivityThread.main(ActivityThread.java:4424)
03-19 21:27:34.263: E/AndroidRuntime(26498):    at java.lang.reflect.Method.invokeNative(Native Method)
03-19 21:27:34.263: E/AndroidRuntime(26498):    at java.lang.reflect.Method.invoke(Method.java:511)
03-19 21:27:34.263: E/AndroidRuntime(26498):    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:784)
03-19 21:27:34.263: E/AndroidRuntime(26498):    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:551)
03-19 21:27:34.263: E/AndroidRuntime(26498):    at dalvik.system.NativeStart.main(Native Method)
03-19 21:27:36.604: I/Process(26498): Sending signal. PID: 26498 SIG: 9
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1 Answer

  1. Editorial Team

    Either:

    • One of the four strings being passed in is null. Check the strings being passed in, right at the start of the method.

    or

    • One of the strings being pulled from the database is null. And add some logging to see if any of the strings from the DB are null.

    If you want two null strings to be regarded as equal, then you need to expand your comparison as follows:

    if ((s1 == null && c.isNull(cst1)) || 
    (s1 != null && !c.isNull(cst1) && s1.equals(c.getString(cst1)))
    ... repeat for the other three string-pairs       
   )
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