使用随机模式时，每个ImageView如何显示不同的图片？ Android Studio

Question

I have 4 images set on random, but when I test it out the result shows the same pictures. I want each image view to show an image different from the others.

This is my code:

 final ImageButton imageButton=(ImageButton) findViewById(R.id.imageView);
        imageButton.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                imageButton.setVisibility(View.INVISIBLE);
                pic1 = (ImageView) findViewById(R.id.imageView2);
                pic2 = (ImageView) findViewById(R.id.imageView3);
                pic3 = (ImageView) findViewById(R.id.imageView4);
                pic4 = (ImageView) findViewById(R.id.imageView5);

                Random rand = new Random();
                int rndInt = rand.nextInt(4) + 1;
                String imgName = "img" + rndInt;
                int id = getResources().getIdentifier(imgName, "drawable", getPackageName());
                pic1.setImageResource(id);
                pic2.setImageResource(id);
                pic3.setImageResource(id);
                pic4.setImageResource(id);

            }
        });

Answer 1

Looking to your code you replace ALL the 4 pic with the same image (for example "img1" or "img2" or "img3" or "img4")

if you want to replace the 4 pic with different image simply call:

int rndInt = rand.nextInt(4) + 1;
String imgName = "img" + rndInt;
int id = getResources().getIdentifier(imgName, "drawable", getPackageName());

every time before assign the resource id to the ImageView.

Create a function for example:

private int getRandomImage() {
    int rndInt = rand.nextInt(4) + 1;
    String imgName = "img" + rndInt;
    return getResources().getIdentifier(imgName, "drawable", getPackageName());
}

and call for each ImageView

pic1.setImageResource(getRandomImage());
pic2.setImageResource(getRandomImage());
pic3.setImageResource(getRandomImage());
pic4.setImageResource(getRandomImage());

EDIT:

If you want to have 4 DIFFERENT images you can change the getRandomImage() with:

List<Integer> listImageUsed = new ArrayList<Integer>();

private int getRandomImage() {
    int rndInt;
    do {
        rndInt = rand.nextInt(4) + 1;
    } while (!listImageUsed.contains(rndInt));

    listImageUsed.add(rndInt);

    String imgName = "img" + rndInt;
    return getResources().getIdentifier(imgName, "drawable", getPackageName());
}

Answer 2

here is my answere, the other attemps are displaying just 4 different images. My solution provides, that the images are random and not identical:

            final ImageButton imageButton=(ImageButton) findViewById(R.id.imageView);
                    imageButton.setOnClickListener(new View.OnClickListener() {
                        @Override
                        public void onClick(View v) {
                            imageButton.setVisibility(View.INVISIBLE);
                            pic1 = (ImageView) findViewById(R.id.imageView2);
                            pic2 = (ImageView) findViewById(R.id.imageView3);
                            pic3 = (ImageView) findViewById(R.id.imageView4);
                            pic4 = (ImageView) findViewById(R.id.imageView5);

                            ArrayList<Integer> imageIds= new ArrayList<>(Arrays.asList(1, 2, 3, 4))
                            Collections.shuffle(imageIds);

                            pic1.setImageResource(getResources().getIdentifier("img" + imageIds[0], "drawable", getPackageName()));
                            pic2.setImageResource(getResources().getIdentifier("img" + imageIds[1], "drawable", getPackageName()));
                            pic3.setImageResource(getResources().getIdentifier("img" + imageIds[2], "drawable", getPackageName()));
                            pic4.setImageResource(getResources().getIdentifier("img" + imageIds[3], "drawable", getPackageName()));

                        }
                    });

Well also you don't have to change much of your code to make it work ;) Sorry that i packed everything in one line. But Iam really tired for in germany it is almost midnight.

Answer 3

It is the same image because "id" only get set once, to get difference Id's you would have to generate more random numbers. You need to call rand.nextInt(4) four times. Once after each ".setImageResource(id)"

Just to give you an idea.

Random rand = new Random();
int rndInt = rand.nextInt(4) + 1;
String imgName = "img" + rndInt;
int id = getResources().getIdentifier(imgName, "drawable", getPackageName());
pic1.setImageResource(id);
//Here you re-generate a random number
rndInt = rand.nextInt(4) + 1;
imgName = "img" + rndInt;
id = getResources().getIdentifier(imgName, "drawable", getPackageName());
pic2.setImageResource(id);

Answer 4

     final ImageButton imageButton=(ImageButton) findViewById(R.id.imageView);
            imageButton.setOnClickListener(new View.OnClickListener() {
                @Override
                public void onClick(View v) {
                    imageButton.setVisibility(View.INVISIBLE);
                    pic1 = (ImageView) findViewById(R.id.imageView2);
                    pic2 = (ImageView) findViewById(R.id.imageView3);
                    pic3 = (ImageView) findViewById(R.id.imageView4);
                    pic4 = (ImageView) findViewById(R.id.imageView5);


                  setRandomImage(pic1);
                  setRandomImage(pic2);
                  setRandomImage(pic3);
                  setRandomImage(pic4);
                }
            });
private void setRandomImage(ImageView imgView)
{
   Random rand = new Random();
   int rndInt = rand.nextInt(4) + 1;
   String imgName = "img" + rndInt;
   int id = getResources().getIdentifier(imgName, "drawable", getPackageName());
   imgView.setImageResource(id);
}