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隨機生成5位大小寫字母或者數(shù)字
方法一：生成不重復(fù)的
- public static void main(String[] args) {
- Random rand = new Random();
- char[] letters=new char[]{'A','B','C','D','E','F','G','H','I','J','K','L','M','N','O','P','Q',
- 'R','S','T','U','V','W','X','Y','Z','a','b','c','d','e','f','g','h','i',
- 'j','k','l','m','n','o','p','q','r','s','t','u','v','w','x','y','z','r',
- '0','1','2','3','4','5','6','7','8','9'};
- String str = "";
- int index;
- boolean[] flags = new boolean[letters.length];//默認為false
- for(int i=0;i<5;i++){
- do{
- index = rand.nextInt(letters.length);
- }while(flags[index]==true);
- char c = letters[index];
- str += c;
- flags[index]=true;
- }
- System.out.println(str);
- }
方法二：生成重復(fù)的，與方法一類似
- public static void main(String[] args) {
- Random rand = new Random();
- char[] letters=new char[]{'A','B','C','D','E','F','G','H','I','J','K','L','M','N','O','P','Q',
- 'R','S','T','U','V','W','X','Y','Z','a','b','c','d','e','f','g','h','i',
- 'j','k','l','m','n','o','p','q','r','s','t','u','v','w','x','y','z','r',
- '0','1','2','3','4','5','6','7','8','9'};
- String str = "";
- int index;
- boolean[] flags = new boolean[letters.length];//默認為false
- for(int i=0;i<5;i++){
- do{
- index = rand.nextInt(letters.length);
- }while(flags[index]==true);
- char c = letters[index];
- str += c;
- flags[index]=true;
- }
- System.out.println(str);
- }
- public static void main(String[] args) {
- String str = "";
- Random rand = new Random();
- for(int i=0;i<5;i++){
- int num = rand.nextInt(3);
- switch(num){
- case 0:
- char c1 = (char)(rand.nextInt(26)+'a');//生成隨機小寫字母
- str += c1;
- break;
- case 1:
- char c2 = (char)(rand.nextInt(26)+'A');//生成隨機大寫字母
- str += c2;
- break;
- case 2:
- str += rand.nextInt(10);//生成隨機數(shù)字
- }
- }
- System.out.println("生成的5個隨機驗證碼是:"+str);
- }
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