数组的使用

一、for循环

int[] num = {2,4,6,8,10};
for (int i = 0; i < 5; i++) {
    System.out.println(num[i]);
}

二、for-each循环

int[] num = {2,4,6,8,10};
for (int x:num) {
    System.out.println(x);
}

三、数组作方法入参

public class Demo {
    public static void main(String[] args) {
        int[] num = {2,4,6,8,10};
        //调用print方法
        print(num);
    }
    //打印数组
    public static void print(int array[]){
        for (int x:array){
            System.out.println(x);
        }
    }
}

四、数组作返回值

public class Demo {
    public static void main(String[] args) {
        int[] num = {2,4,6,8,10};
        //调用reverse方法
        for (int x:reverse(num)){
            System.out.println(x);
        }
    }
    public static int[] reverse(int num[]){
        int[] result = new int[num.length];
        //反转数组
        for (int i=0,j=num.length-1;i<num.length;i++,j--){
            result[j]=num[i];
        }
        return result;
    }
}

五、二维数组

简单理解就是数组里边的元素是数组

以前觉得很绕的一个地方，现在突然理解了！！！

int a[][] = new int[2][3];

或者

int a[][] = {{1,2},{3,4},{5,6},{7,8}};
for (int i=0;i<a.length;i++){
    for (int j=0;j<a[i].length;j++){
        System.out.print(a[i][j]+" ");
    }
}