java数组

数组的声明和创建

package com.zhan.array;

public class ArrayDemo01 {
    public static void main(String[] args) {
        int[] nums = new int[10];//声明一个数组，创建一个数组
        //给数组元素中赋值
        nums[0] = 0;
        nums[1] = 1;
        nums[2] = 2;
        nums[3] = 3;
        nums[4] = 4;
        nums[5] = 5;
        nums[6] = 6;
        nums[7] = 7;
        nums[8] = 8;
        nums[9] = 9;
        nums[10] = 10;
        //计算所有元素的和
        int sum = 0;
        //获取数组的长度arrays.length
        for (int i = 0; i < nums.length; i++) {
            sum = sum+nums[i];
        }
        System.out.println("总和为"+sum);

    }
}

 静态初始化和动态初始化

package com.zhan.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};
        System.out.println(a[0]);
        //动态初始化 ： 包含默认初始化
        int[] b = new int[10];
        b[0] = 10;
        b[1] = 10;
        System.out.println(b[0]);
        System.out.println(b[1]);
        System.out.println(b[2]);
        System.out.println(b[3]);
    }
}

数组的使用

package com.zhan.array;

public class ArrayDemo03 {
    public static void main(String[] args) {
        //打印数组元素
        int[] arrays = {1,2,3,4,5};
        for (int i = 0; i < arrays.length; i++) {
            System.out.println(arrays[i]);
        }
        System.out.println("====================");
        //计算所有数组元素的和
        int  sum = 0;
        for (int i = 0; i < arrays.length; i++) {
            sum +=arrays[i];
        }
        System.out.println("数组中所有的和为："+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("数组中的最大元素为："+max);
    }
}








package com.zhan.array;

import java.lang.reflect.Array;
import java.util.Arrays;

public class ArrayDemo04 {
    public static void main(String[] args) {
        int[] arrays = {1,2,3,4,5};
        for (int array : arrays){
            System.out.println(array);
        }
       //printArray(arrays);
        System.out.println("============");
        int[] transform = transform(arrays);
        printArray(transform);
    }

    public static void printArray(int[] arrays) {
        for (int i = 0; i < arrays.length; i++) {
            System.out.println(arrays[i]+" ");
        }
       // System.out.println("========================");
    }
// 反转数组

public static int[] transform(int[] array){
     int[] num = new int[array.length];
     int c = 10;
     for (int i = 0,j=array.length-1; i 

二维数组

package com.zhan.array;

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

    }



}

Array类

package com.zhan.array;

import java.util.Arrays;

public class ArrayDemo06 {
    public static void main(String[] args) {
        int[] a = {1,6,4,2,3,7,8,9,1};
        //打印数组元素Arrays.toString
        System.out.println(Arrays.toString(a));
        Arrays.sort(a);//数组进行排序 ： 升序
        System.out.println(Arrays.toString(a));

        Arrays.fill(a,0);//数组填充
        System.out.println(Arrays.toString(a));
        Arrays.fill(a,2,4,0);
        System.out.println(Arrays.toString(a));
    }
}

冒泡排序

package com.zhan.array;

import java.util.Arrays;

public class ArrayDemo07 {
    public static void main(String[] args) {
        int[] array = {12,132,23,15,8,6,45,64,84};
        int[] sort = sort(array);
        System.out.println(Arrays.toString(sort));
    }
    public static int[] sort(int[] array){
        int temp = 0;
        for (int i = 0; i < array.length - 1; i++) {
            boolean flag = false;
            for (int j = 0; j < array.length - 1 - i; j++) {
                if (array[j]>array[j+1]){
                    temp = array[j];
                    array[j] = array[j+1];
                    array[j+1] = temp;
                    flag = true;
                }
                if (flag==false){
                    break;
                }
            }
        }
        return array;
    }
}