数组的使用

数组的使用

• 普通的For循环
• For-Each循环
• 数组作方法入参
• 数组作返回值

package com.wang.array;

public class ArrayDemo03 {
    public static void main(String[] args) {
        int[] arrays = {1,2,5,4,3};

        //打印全部的数组元素
        for (int i = 0; i < arrays.length; i++) {
            System.out.println(arrays[i]);
        }
        System.out.println("============");
        //计算所有元素的和
        int sum = 0;
        for (int i = 0; i < arrays.length; i++) {
            sum += arrays[i];
        }
        System.out.println("sum = " + sum);
        System.out.println("============");
        //查找最大的元素
        int max = arrays[0];
        for (int i = 1; i < arrays.length; i++) {
            if (arrays[i] > max){
                max = arrays[i];
            }
        }
        System.out.println("max = " +max);

    }
}

package com.wang.array;

public class ArrayDemo04 {
    public static void main(String[] args) {
        int[] arrays = {1,2,3,4,5};

        //JDK1.5 没有下标
        for(int array : arrays){
            System.out.println(array);
        }
       printArray(arrays);
        int[] reverseArray = reverse(arrays);
        printArray(reverseArray);
    }

    //打印数组元素
    public static void printArray(int[] arrays){
        for (int i = 0; i < arrays.length; i++) {
            System.out.print(arrays[i]+" ");
        }
    }
    //反转数组
    public static int[] reverse(int[] arrays){
        int[] result = new int[arrays.length];
        //反转的操作
        for (int i = 0, j = result.length-1; i < arrays.length; i++,j--) {
            result[j] = arrays[i];
        }
        return result;
    }

}