Question

这是我的代码，我试图随机添加元素。有没有办法使用while循环，for循环或Java中的每个循环添加元素？

package arrays_into_2d_array;

import java.util.*;

public class Arrays2DArray {

    /**
     * @param args the command line arguments
     */
    public static void main(String[] args) {

    Random random = new Random();

    int [] arr1 = new int[50];
    for(int i = 0; i < arr1.length; i++){
        arr1[i] = 1+random.nextInt(5);
    }
    int [] arr2 = new int[100];
        for(int i = 0; i < arr2.length; i++){
        arr2[i] = 1+random.nextInt(5);
    }
    int [] arr3 = new int[200];
        for(int i = 0; i < arr3.length; i++){
        arr3[i] = 1+random.nextInt(5);
    }
    int [] arr4 = new int[400];
        for(int i = 0; i < arr4.length; i++){
        arr4[i] = 1+random.nextInt(5);
    }
    int [] arr5 = new int[800];
        for(int i = 0; i < arr5.length; i++){
        arr5[i] = 1+random.nextInt(5);
    }
    int [] arr6 = new int[1600];
        for(int i = 0; i < arr6.length; i++){
        arr6[i] = 1+random.nextInt(5);
    }
    int [] arr7 = new int[3200];
        for(int i = 0; i < arr7.length; i++){
        arr7[i] = 1+random.nextInt(5);
    }
    int [] arr8 = new int[6400];
        for(int i = 0; i < arr8.length; i++){
        arr8[i] = 1+random.nextInt(5);
    }
    int [] arr9 = new int[12800];
        for(int i = 0; i < arr9.length; i++){
        arr9[i] = 1+random.nextInt(5);
    }
    int [] arr10 = new int[25600];
        for(int i = 0; i < arr10.length; i++){
        arr10[i] = 1+random.nextInt(5);
    }


    int [][] arr2D = {arr1, arr2, arr3, arr4, arr5, arr6, arr7, arr8, arr9, arr10};

    for(int i = 0; i < arr2D.length; i++){
        System.out.println("Index = "+i+" of 2D array has = "+arr2D[i].length+" number of elements.");
    }

    }

}

任何帮助将不胜感激。

Answer 1

您编写的代码太多，几乎相同，因此您应该使用循环。

package arrays_into_2d_array;

import java.util.*;

public class Arrays2DArray {

    /**
     * @param args the command line arguments
     */
    public static void main(String[] args) {

        Random random = new Random();
        int [] sizes = {50, 100, 200, 400, 800, 1600, 3200, 6400, 12800, 25600};
        int [][] arr2D = new int[sizes.length][];
        for(int i = 0; i < arr2D.length; i++){
            arr2D[i] = new int[sizes[i]];
            for(int j = 0; j < arr2D[i].length; j++){
                arr2D[i][j] = 1+random.nextInt(5);
            }
        }

        for(int i = 0; i < arr2D.length; i++){
            System.out.println("Index = "+i+" of 2D array has = "+arr2D[i].length+" number of elements.");
        }

    }

}

Answer 2

当然。您正在寻找的是一种方法。

您将声明一个接受int[]和Random实例并执行循环的方法：

public static void assignRandomValues(int[] array, Random random)
{
    for (int i = 0; i < array.length; i++)
    {
        array[i] = 1 + random.nextInt(5);
    }
}

然后你会把你的代码变成这个：

int[] arr1 = new int[50];
assignRandomValues(arr1, random);

......等等。

Answer 3

Not exactly a loop, but the java 8 version using the stream API is definetly short:

int[][] arr2D = IntStream.range(0, 10).map(i -> 50 << i) // stream of sizes
                         .mapToObj(size -> IntStream.generate(() -> random.nextInt(5) + 1).limit(size).toArray()) // stream of arrays with given sizes
                         .toArray(int[][]::new); // combine arrays

是否有更短的代码或更简单的方法将元素添加到不同大小的多个数组？

3 个答案: