23-数组的使用

public class Demo03 {
    public static void main(String[] args) {
        int [] arrays = {1,2,3,4,5,99};
        //打印全部数组元素
        for (int i = 0; i < arrays.length; i++) {
            System.out.println(arrays[i]);
        }
        //求和
        int sum = 0;
        for (int i = 0; i < arrays.length; i++) {
            sum = sum + arrays[i];
        }
        System.out.println(sum);
        //查找最大元素
        int max = arrays[0];
        for (int i = 0; i < arrays.length; i++) {
            if (arrays[i]>max) {
                max=arrays[i];
            }
        }
        System.out.println(max);
    }
}

数组的增强for循环

public class Demo04 {
    public static void main(String[] args) {
        int[] array = {10,20,30,40,50,60};
        for (int i : array) {
            System.out.println(i);
        }
    }
}

public class Demo04 {
    public static void main(String[] args) {
        int[] arrays = {10,20,30,40,50,60};
        printArrays(arrays);//调用打印数组方法
    }

    //建一个方法-打印数组元素
    public static void printArrays (int[] arrays){
        for (int i = 0; i < arrays.length; i++) {
            System.out.print(arrays[i]+" ");
        }
    }

public class Demo05 {

    public static void main(String[] args) {
        int [] a = {1,2,3,4,5,6,7};
        int [] reverse = reverse(a); //调用反转
        printArrays(reverse);        //调用打印
    }

    //建一个-反转数组方法
    public static int[] reverse(int[] arrays){
        int[] result = new int[arrays.length];

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

        return result;
    }

    //打印数组元素建方法
    public static void printArrays(int[] arrays) {
        for (int i = 0; i < arrays.length; i++) {
            System.out.print(arrays[i] + " ");
        }
    }
}

反转数组方法2

import java.util.Arrays;

public class Demo12 {
    public static void main(String[] args) {
        int[] array = {1,2,3,4,5,6,7,8,9,10};
        int temp = 0;
        for (int i = 0; i < array.length/2; i++) {
             temp = array[array.length - 1 - i];
             array[array.length - 1 - i] = array[i];
             array[i] = temp;
        }
        System.out.println(Arrays.toString(array));
    }
}

多维数组

public class Demo06 {
    public static void main(String[] args) {
        int[][] arrays = {{1,2},{10,20,30},{100,200},{1000,2000,20},{10000,20000},};

        for (int i = 0; i < arrays.length; i++) {

            for (int k = 0; k < arrays[i].length; k++) {
                System.out.print(arrays[i][k]+"\t");
            }
            System.out.println();
        }
    }
}

二维数组，也可以用两个增强for循环打印出各个数值

public class Test3 {
    public static void main(String[] args) {

    int[][] a = {{2,95,87,0},{7,69,5},{2},{99,7789},{1,2,3,4,5,6,7},{9,9,9,9,9},{9595,8712}};
        for (int[] i : a) {  //外层增强for循环

            for (int i1 : i) {  //内层增强for循环
                System.out.print(i1+" ");
            }
            System.out.println();
            }
            }
        }