1.代码：

package day20181015;
import java.util.Arrays;
/**
* 验证码的实现
* @author Administrator
*/
public class ArrayDemo {
public static void main(String[] args) {
/* 存放所有验证码的字符串 */
String[] pool = { "0", "1", "2", "3", "4", "5", "6", "7", "A", "B",
"C", "F", "T", "S" };// 下标 0~pool.length-1
// 标记上面pool中的元素是否被取过
boolean[] used = new boolean[pool.length];
// 存放验证码
String[] code = new String[6];
int i = 0;// code下标
// 循环产生验证码
while (true) {
// 随机下标
int index = (int) (Math.random() * pool.length);
if (used[index]) {// 字符串被取出过
continue;
}
used[index] = true;
code[i++] = pool[index];// 将随机出来的字符串存放到数组中
if ( i== 6) {
break;
}
}
System.out.println("验证码：" + Arrays.toString(code));
}
}

2.代码‘：

package day20181016;
import java.util.Scanner;
public class MaxDataDemo {
public static void main(String[] args) {
Scanner input=new Scanner(System.in);
int[]scores=new int[5];
for(int i=0;i<scores.length;i++){
System.out.print("请输入第"+(i+1)+"次成绩：");
scores[i]=input.nextInt();
}
int maxScore=scores[0];
for(int i=1;i<scores.length;i++){
if(scores[i]>maxScore){
maxScore=scores[i];
}
}
System.out.print("五门成绩的最高分为："+maxScore);
}
}