我如何使随机显示的图像不再重复？

Question

我正在使用Android Studio制作通用应用；我想从我的阵列中显示4个随机图像，但不知道如何防止图像重复。

public class answerScreen extends AppCompatActivity {
ImageView imageView, imageView2, imageView3, imageView4;
Random r;
Integer[] images = {
        R.drawable.img1,
        R.drawable.img2,
        R.drawable.img3,
        R.drawable.img4,
        R.drawable.img5,
        R.drawable.img6,
        R.drawable.img7
};


@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_answer_screen);

    imageView = (ImageView) findViewById(R.id.imageView);
    imageView2 = (ImageView) findViewById(R.id.imageView2);
    imageView3 = (ImageView) findViewById(R.id.imageView3);
    imageView4 = (ImageView) findViewById(R.id.imageView4);

    r = new Random();

    //diplay random image
    imageView.setImageResource(images[r.nextInt(images.length)]);
    imageView2.setImageResource(images[r.nextInt(images.length)]);
    imageView3.setImageResource(images[r.nextInt(images.length)]);
    imageView4.setImageResource(images[r.nextInt(images.length)]);
}
}

Answer 1

您可以在[0,images.length)范围内生成4个随机整数，并将它们存储在数组中，例如：

Random r = new Random();
int randInts [] = r.ints(0, images.length).distinct().limit(4).toArray();

并使用该数组设置图像资源：

imageView.setImageResource(images[randInts[0]]);
imageView2.setImageResource(images[randInts[1]]);
imageView3.setImageResource(images[randInts[2]]);
imageView4.setImageResource(images[randInts[3]]);

Answer 2

将数组改组然后获取前四个项目是执行此操作的一种简单方法。一个简单的例子：

Integer[] intArray = { 1, 2, 3, 4, 5, 6, 7 };

List<Integer> intList = Arrays.asList(intArray);
Collections.shuffle(intList);
intList.toArray(intArray);

System.out.println(Arrays.toString(intArray));

我是从https://www.journaldev.com/32661/shuffle-array-java那里得到的