How to disable all the buttons in the layout for a certain amount of time, java.NullPointerException

Question

secondScreen.java

public class secondScreen extends Activity implements View.OnClickListener {

//drawables
int res[] = new int[] {R.drawable.brownbars,R.drawable.centeredorangedot, R.drawable.dots, R.drawable.greenlines, R.drawable.lightbulb, R.drawable.orangedots, R.drawable.orangelines, R.drawable.tree, R.drawable.yellow, R.drawable.yellowwithred, R.drawable.brownbars,R.drawable.centeredorangedot,
        R.drawable.dots, R.drawable.greenlines, R.drawable.lightbulb, R.drawable.orangedots, R.drawable.orangelines, R.drawable.tree, R.drawable.yellow, R.drawable.yellowwithred};
int lay1, lay2, shuffleCount = 0, gameCount = 0;
ImageButton first, second;
LinearLayout layout;


ImageButton b1;
ImageButton b2;
ImageButton b3;
ImageButton b4;
ImageButton b5;
ImageButton b6;
ImageButton b7;
ImageButton b8;
ImageButton b9;
ImageButton b10;
ImageButton b11;
ImageButton b12;
ImageButton b13;
ImageButton b14;
ImageButton b15;
ImageButton b16;
ImageButton b17;
ImageButton b18;
ImageButton b19;
ImageButton b20;



@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);

    setContentView(R.layout.layout);
    Intent activityThatCalled = getIntent();


    //initialize all buttons in game
    b1 = (ImageButton) findViewById(R.id.b1);
    b2 = (ImageButton) findViewById(R.id.b2);
    b3 = (ImageButton) findViewById(R.id.b3);
    b4 = (ImageButton) findViewById(R.id.b4);
    b5 = (ImageButton) findViewById(R.id.b5);
    b6 = (ImageButton) findViewById(R.id.b6);
    b7 = (ImageButton) findViewById(R.id.b7);
    b8 = (ImageButton) findViewById(R.id.b8);
    b9 = (ImageButton) findViewById(R.id.b9);
    b10 = (ImageButton) findViewById(R.id.b10);
    b11 = (ImageButton) findViewById(R.id.b11);
    b12 = (ImageButton) findViewById(R.id.b12);
    b13 = (ImageButton) findViewById(R.id.b13);
    b14 = (ImageButton) findViewById(R.id.b14);
    b15 = (ImageButton) findViewById(R.id.b15);
    b16 = (ImageButton) findViewById(R.id.b16);
    b17 = (ImageButton) findViewById(R.id.b17);
    b18 = (ImageButton) findViewById(R.id.b18);
    b19 = (ImageButton) findViewById(R.id.b19);
    b20 = (ImageButton) findViewById(R.id.b20);

    iconRandomizer();



};

public void randomCheck(ImageButton btn, int image) {

    if (gameCount < 2) {
        gameCount++;
        if (gameCount == 1) {
            first = btn;
            lay1 = image;
        } else {
            second = btn;
            lay2 = image;


            if (lay1 != lay2) {
                ArrayList<View> touchables = layout.getTouchables();
                for(View touchable : touchables) {
                    if (touchable instanceof Button)
                        ((Button) touchable).setEnabled(false);
                }
                Handler handler = new Handler();
                handler.postDelayed(new Runnable() {
                    public void run() {
                        first.setImageResource(R.color.material_blue_grey_800);
                        second.setImageResource(R.color.material_blue_grey_800);
                        first.setEnabled(true);
                        second.setEnabled(true);

                    }
                }, 1000);

            }
            gameCount = 0;

        }


    }
}

static void shuffleArray(int[] ar)
{
    Random rnd = new Random();
    for (int i = ar.length - 1; i > 0; i--)
    {
        int index = rnd.nextInt(i + 1);
        // Simple swap
        int a = ar[index];
        ar[index] = ar[i];
        ar[i] = a;
    }
}




public void iconRandomizer() {

    for (int i = 0; i < 10; i++)
        System.out.println(res[i]);


    shuffleArray(res);

    for (int i = 0; i < 10; i++)
        System.out.println(res[i]);

    b1.setOnClickListener(this);
    b2.setOnClickListener(this);
    b3.setOnClickListener(this);
    b4.setOnClickListener(this);
    b5.setOnClickListener(this);
    b6.setOnClickListener(this);
    b7.setOnClickListener(this);
    b8.setOnClickListener(this);
    b9.setOnClickListener(this);
    b10.setOnClickListener(this);
    b11.setOnClickListener(this);
    b12.setOnClickListener(this);
    b13.setOnClickListener(this);
    b14.setOnClickListener(this);
    b15.setOnClickListener(this);
    b16.setOnClickListener(this);
    b17.setOnClickListener(this);
    b18.setOnClickListener(this);
    b19.setOnClickListener(this);
    b20.setOnClickListener(this);

}




public void onClick(View v){


    switch (v.getId()){
        case R.id.b1:
            b1.setImageResource(res[0]);
            b1.setEnabled(false);
            randomCheck(b1, res[0]);

            break;
        case R.id.b2:
            b2.setImageResource(res[1]);
            b2.setEnabled(false);
            randomCheck(b2,res[1]);

            break;
        case R.id.b3:
            b3.setImageResource(res[2]);
            b3.setEnabled(false);
            randomCheck(b3, res[2]);

            break;
        case R.id.b4:
            b4.setImageResource(res[3]);
            b4.setEnabled(false);
            randomCheck(b4, res[3]);

            break;
        case R.id.b5:
            b5.setImageResource(res[4]);
            b5.setEnabled(false);
            randomCheck(b5, res[4]);

            break;
        case R.id.b6:
            b6.setImageResource(res[5]);
            b6.setEnabled(false);
            randomCheck(b6, res[5]);

            break;
        case R.id.b7:
            b7.setImageResource(res[6]);
            b7.setEnabled(false);
            randomCheck(b7, res[6]);

            break;
        case R.id.b8:
            b8.setImageResource(res[7]);
            b8.setEnabled(false);
            randomCheck(b8, res[7]);

            break;
        case R.id.b9:
            b9.setImageResource(res[8]);
            b9.setEnabled(false);
            randomCheck(b9, res[8]);

            break;
        case R.id.b10:
            b10.setImageResource(res[9]);
            b10.setEnabled(false);
            randomCheck(b10, res[9]);

            break;
        case R.id.b11:
            b11.setImageResource(res[10]);
            b11.setEnabled(false);
            randomCheck(b11, res[10]);

            break;
        case R.id.b12:
            b12.setImageResource(res[11]);
            b12.setEnabled(false);
            randomCheck(b12, res[11]);

        case R.id.b13:
            b13.setImageResource(res[12]);
            b13.setEnabled(false);
            randomCheck(b13, res[12]);

            break;
        case R.id.b14:
            b14.setImageResource(res[13]);
            b14.setEnabled(false);
            randomCheck(b14, res[13]);

        case R.id.b15:
            b15.setImageResource(res[14]);
            b15.setEnabled(false);
            randomCheck(b15, res[14]);

            break;
        case R.id.b16:
            b16.setImageResource(res[15]);
            b16.setEnabled(false);
            randomCheck(b16, res[15]);

            break;
        case R.id.b17:
            b17.setImageResource(res[16]);
            b17.setEnabled(false);
            randomCheck(b17, res[16]);

            break;
        case R.id.b18:
            b18.setImageResource(res[17]);
            b18.setEnabled(false);
            randomCheck(b18, res[17]);

            break;
        case R.id.b19:
            b19.setImageResource(res[18]);
            b19.setEnabled(false);
            randomCheck(b19, res[18]);

            break;
        case R.id.b20:
            b20.setImageResource(res[19]);
            b20.setEnabled(false);
            randomCheck(b20, res[19]);


            break;
    }


}

//}

}

error log:

  java.lang.NullPointerException: Attempt to invoke virtual method 'java.util.ArrayList android.widget.LinearLayout.getTouchables()' on a null object reference
        at eagle.abhishekravi.abhishek.eagle.secondScreen.randomCheck(secondScreen.java:111)
        at eagle.abhishekravi.abhishek.eagle.secondScreen.onClick(secondScreen.java:232)
        at android.view.View.performClick(View.java:4780)
        at android.view.View$PerformClick.run(View.java:19866)
        at android.os.Handler.handleCallback(Handler.java:739)
        at android.os.Handler.dispatchMessage(Handler.java:95)
        at android.os.Looper.loop(Looper.java:135)
        at android.app.ActivityThread.main(ActivityThread.java:5254)
        at java.lang.reflect.Method.invoke(Native Method)
        at java.lang.reflect.Method.invoke(Method.java:372)
        at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:903)
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:698)

I am making a memory match game, and I need to disable all buttons after the second Button is tapped. Then after the check is complete, it will resume normally. I have got the checks to work but still need the buttons disabled in this case where user taps another Button between the 1 second pause.Let me know if you need more information. Thanks!!

Answer 1

Based on the information provided by the error message, it looks like layout is null. If you're still having trouble, the code where layout is being set would be very helpful.

Your layout should be accessed via R.layout.my_layout .