day04数组01

package com.qinhan.array;

public class ArrayDemo01 {
    //变量的类型    变量的名称    =   变量的值
    public static void main(String[] args) {

        int[] nums ; //声明一个数组

        nums = new int[10];// 创建一个数组

        //给数组元素中赋值
        nums[0] = 1;
        nums[1] = 2;
        nums[2] = 3;
        nums[3] = 4;
        nums[4] = 5;
        nums[5] = 6;
        nums[6] = 7;
        nums[7] = 8;
        nums[8] = 9;
        nums[9] = 10;

        //计算所有元素的和
        int sum = 0;
        //获取数组长度    arrays.length
        for (int i = 0; i < nums.length; i++){
            sum += nums[i];
        }
        System.out.println("总和为："+sum);

    }
}

　　

package com.qinhan.array;

public class ArrayDemo02 {
    public static void main(String[] args) {
        //静态初始化： 创建  +  赋值
        int[] a = {1,2,3,4,5,6,7,8,9};
        System.out.println(a[5]);

        //动态初始化 ： 包含默认初始化
        int[] b = new int[10];
        b[0] = 1;
        System.out.println(b[0]);
    }
}

　　

package com.qinhan.array;

public class ArrayDemo03 {
    public static void main(String[] args) {
        int[] arrays = {1,2,3,4,5,6};

        //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("===================");
        //计算所有元素的总和
        int sum = 0;
        for (int i = 0; i < arrays.length; i++){
            sum += arrays[i];
        }
        System.out.println("总和为："+sum);
        System.out.println("===================");
        //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("最大值为："+max);

    }
}

　　

package com.qinhan.array;

public class ArrayDemo04 {
    public static void main(String[] args) {
        int[] arrays = {1,2,3,4,5,6,7,8};
        //JDK1.5   没有下标
//        for (int array : arrays) {
//            System.out.println(array);
//        }
        printArray(arrays);
        int[] reverse = reverse(arrays);
        printArray(reverse);

    }
    //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;
    }
}

　　

package com.qinhan.array;

public class ArrayDemo05 {
    public static void main(String[] args) {
        //[6][2]
        /*
        1,2  arrays[0]
        2,3  arrays[1]
        3,4  arrays[2]
        4,5  arrays[3]
        5,6  arrays[4]
        6,7  arrays[5]
         */
        int[][] arrays = {{1,2},{2,3},{3,4},{4,5},{5,6},{6,7}};
        //printArray(arrays[0]);
//        System.out.println(arrays[0][0]);
//        System.out.println(arrays[0][1]);
//        System.out.println(arrays.length);
//        System.out.println(arrays[0].length);
        for (int i = 0; i < arrays.length ; i++){
            for (int j = 0; j < arrays[i].length ;j++){
                System.out.println(arrays[i][j]);
            }
        }
    }
    public static void printArray(int[] arrays){
        for (int i = 0; i < arrays.length; i++){
            System.out.print(arrays[i]+" ");
        }
    }
}