简单的验证码生成器

String有length的属性吗?数组有length的方法吗? String只有length的方法，数组有length的属性

package com.faust.java.system.services;

import java.util.Random;

public class Array {

public static void main(String[] args) {
// TODO Auto-generated method stub
Random r = new Random();
for (int i = 0; i < 4; i++) {
int type = r.nextInt(3);
// if (type == 0) {
// System.out.print(r.nextInt(10));
// } else if (type == 1) {
// System.out.print((char) (r.nextInt(26) + 97));
// } else {
// System.out.print((char) (r.nextInt(26) + 65));
// }
switch (type) {
case 0:
System.out.print(r.nextInt(10));
break;
case 1:
System.out.print((char) (r.nextInt(26) + 97));
break;
case 2:
System.out.print((char) (r.nextInt(26) + 65));
break;

}
}

}
}

冒泡排序

 

package com.faust.java.supplier.dao;

import java.util.Arrays;
public class demo1 {

public static void main(String[] args) {
// TODO Auto-generated method stub
int[] arr = { 99, 5, 8, 9, 55 };
for (int i = 0; i < arr.length - 1; i++) {
for (int j = 0; j < arr.length - i - 1; j++) {
if (arr[j + 1] < arr[j]) {
int temp = arr[j + 1];
arr[j + 1] = arr[j];
arr[j] = temp;
for (int k : arr) {
System.out.println(k);
}
System.out.println(Arrays.toString(arr));
}

}
}

}

}

 

选择排序

package com.faust.java.supplier.dao;

import java.util.Arrays;

public class demo2 {

public static void main(String[] args) {
// TODO Auto-generated method stub}
int[] arr = { 99, 5, 9, 7, 55 };
for (int i = 0; i < arr.length-1; i++) {
for (int j = i + 1; j < arr.length; j++) {
if (arr[i] > arr[j]) {

int temp = arr[i];
arr[i] = arr[j];
arr[j] = temp;
}
}

}System.out.println(Arrays.toString(arr));
}

}

 

输入分数进行大小排列

package com.faust.java.supplier.services;

import java.util.Arrays;
import java.util.Scanner;

public class Demo1 {

public static void main(String[] args) {
// TODO Auto-generated method stub
// 1 使用输入分数进行冒泡排序，int[] score = new int[5]; 对数组的元素进行赋值，最后进行排序
// 1.进行分数输入进控制台，使用scanner
Scanner sc = new Scanner(System.in);
System.out.print("请输入分数：");
int[] arr = new int[5];
// 进行循环输入分数
for (int i = 0; i < arr.length; i++) {
int score = sc.nextInt();
System.out.print("请继续输入分数：");
// 2.将输入的分数进行保存，放入数组中
arr[i] = score;
}
// 3.将保存好的数组进行冒泡排序
for (int i = 0; i < arr.length - 1; i++) {
for (int j = 0; j < arr.length - i - 1; j++) {
if (arr[j] > arr[j + 1]) {
int temp = arr[j];
arr[j] = arr[j + 1];
arr[j + 1] = temp;
}
}
}
System.out.println(Arrays.toString(arr));
}

}

产生随机数

package com.faust.java.system.dao;

import java.util.Random;

public class RandomDemo {

public static void main(String[] args) {
// TODO Auto-generated method stub
Random ran =new Random();
for (int j = 0; j <4; j++) {
for (int k = 0; k <4; k++) {
int i = ran.nextInt(10);

System.out.print(i);
}
System.out.println();
}
}

}