方法：数组

方法：数组

package com.andy.base.Andy.operator.array;

public class ArrayDemo01 {
    public static void main(String[] args) {

        //变量的类型     变量的名字    =   变量的值;
        //数组类型

        int[] nums;   //1.声明一个数组

        //使用new操作来创建数组
       nums = new int[10];   //2.创建一个数组

        //3.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;

        System.out.println(nums[9]);

        //计算所有元素的和
        int sum = 0;
        //数组的长度  nums.length
        for (int i = 0; i < nums.length ; i++) {
            sum = sum +nums[i];

        }
        System.out.println("总和为："+ sum);

    }
}

package com.andy.base.Andy.operator.array;

public class ArrayDemo02 {
    public static void main(String[] args) {
        //静态赋值
        int[] a ={1,2,3,4,5,6,7,8};
        System.out.println(a[0]);

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

}

数组的使用

package com.andy.base.Andy.operator.array;

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

        //打印全部数组元素
        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="+max);
    }
}

package com.andy.base.Andy.operator.array;

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

//   for (int array : arrays) {
//            System.out.println(array);
//        }     多行注释  ctrl + /    取消 ctrl+shift+/

       // printArray(arrays);
        int[] reverse = reverse(arrays); //reverse(arrays) alt+enter
        printArray(reverse);
    }

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

        //反转操作
        for (int i = 0, j = result.length-1;i < arrays.length ; i++,j--) {
            result[j] = arrays[i];

        }
        return result;
    }
    //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]+"");
        }
    }
}

多维数组

package com.andy.base.Andy.operator.array;

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

        }


    }
    //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]+"");
        }
    }
}

Arrays 类讲解

package com.andy.base.Andy.operator.array;

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

public class ArrayDemo06 {
    public static void main(String[] args) {
        int[] a = {1,2,3,4,528985,28984,277};

        System.out.println(a); //[I@1540e19d

        //打印数组元素Arrays.toString
        System.out.println(Arrays.toString(a));

        printArray(a);
        Arrays.sort(a);//数组进行排序

        System.out.println();
        System.out.println(Arrays.toString(a));

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

    public static void printArray(int[] a){
        for (int i = 0; i < a.length; i++) {
          if(i==0){
              System.out.print("[");
          }
          if(i==a.length-1){
              System.out.print(a[i]+"]");
          }else{
              System.out.print(a[i]+" ,");
          }
        }
    }
}