22、数组使用

数组使用

1、For-Each 循环

public class ArrayDemo05 {
    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);
        }
    }
}

2、数组作方法入参

public class ArrayDemo06 {
    public static void main(String[] args) {
        int[] nums = {1,2,3,4,5};
        printArray(nums);
    }

    //打印数组元素
    public static void printArray(int[] arrays) {
        for ( int i = 0; i < arrays.length; i++ ) {
            System.out.println(arrays[i]);
        }
    }
}

3、数组作返回值

• 反转数组

public class ArrayDemo07 {
    public static void main(String[] args) {
        int[] nums = {1,2,3,4,5,6,7,8};
        int[] reverse = reverse(nums);
        printArray(reverse);
    }

    //反转数组
    public static int[] reverse(int[] arrays) {
        //定义一个新的数组用来存放反转的值
        int[] result = new int[arrays.length];

        for ( int i = 0, j = arrays.length - 1; i < arrays.length; i++, j-- ) {
            result[j] = arrays[i];
        }
        return result;
    }

    //输出数组数据的方法
    public static void printArray(int[] arrays) {
        for ( int array : arrays ) {
            System.out.print(array + " ");
        }
    }
}

4、普通的for循环

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

        //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(arrays.length + "个数的和为：" + sum);

        System.out.println("==============");

        //查找最大元素
        int max = arrays[0];
        for ( int i = 1; i < arrays.length; i++ ) {
            if ( arrays[i] > max ) {
                max = arrays[i];
            }
        }
        System.out.println("最大的数为：" + max);
    }
}