第六周作业

1.定义长度为5的整型数组,输入他们的值,用冒泡排序后输出.

(1)自定义数组：

import java.util.*;
public class L 
{
    public static void main(String[] args) {
           int[] arr = {3,5,9,7,1};
           for (int i = 0; i < arr.length; i++) {
               for (int j = 0; j < arr.length-1-i; j++) {
               int num = 0;
               if(arr[j] > arr[j+1]){
                   num = arr[j];
                   arr[j]= arr[j+1];
                   arr[j+1] = num;
                }
             }
           }
           for (int i : arr) {
               System.out.println(i);
           }
       }
   }

 （2）控制台输入数组：

import java.util.*;
public class L 
{
    public static void main(String[] args) {
        Scanner input=new Scanner(System.in);
        System.out.println("请输入数组的值：");
        int[] arr= new int[5];
        for(int i=0;i<arr.length;i++) {
            arr[i]=input.nextInt();
        }
        for (int i = 0; i < arr.length-1; i++) {
            for (int j = 0; j < arr.length-1-i; j++) {
            if(arr[j] > arr[j+1]){
                int temp=arr[j];
                arr[j]= arr[j+1];
                arr[j+1] = temp;
             }
          }
        }
        System.out.println("升序冒号排序为：");
        for (int i=0;i<arr.length;i++) {
            System.out.println(arr[i]+" ");
        }
    }
}

2.定义数组{34,22,35,67,45,66,12,33},输入一个数a,查找在数组中是否存在,如果存在,输出下标,不存在输出"not found"

import java.util.*;
public class L 
{
    public static void main(String[] args) {
        Scanner input = new Scanner(System.in);
        boolean flag= false;
        int[]arr = {34,22,35,67,45,66,12,33};
        System.out.println("请输入一个数：");
        int a = input.nextInt();
        for (int i = 0; i < arr.length; i++) {
            if (arr[i] == a){
                System.out.println("该数在数组中存在它的下标是：" + i);
                flag = true;
            }
        }
        if(flag == false){
            System.out.println("not found");
        }
  }
}

3.以矩阵的形式输出一个double型二维数组（长度分别为5、4，值自己设定）的值。

import java.util.*;
public class L 
{
    public static void main(String[] args) {
         double arr[][] = { { 1, 2, 3, 4, 5 }, { 6, 7, 8, 9, 10 },
                 { 11, 12, 13, 14, 15 }, { 16, 17, 18, 19, 20 } };
          for (int i = 0; i < arr.length; i++) {
              for (int j = 0; j < arr[i].length; j++) {
                  System.out.print(arr[i][j] + "	");
              } System.out.println();
          }
     }
 }

4.定义一个二维数组(长度分别为3,4,值自己设定),求该二维数组的最大值.

import java.util.*;
public class L 
{
    public static void main(String[] args) {
        int arr[][] = { {1,5,7,9},{6,8,9,7},{12,23,34,45}};
        int max=arr[0][0];
         for (int i = 0; i < arr.length; i++) {
             for (int j = 0; j < arr[i].length; j++) {
                 if(arr[i][j]>max){
                     max=arr[i][j];
                 }
             }
         }
             System.out.println("二维数组中最大的是:"+max);
    }
}