老师，为什么，添加的随机字符中间会有点，怎么去掉
package collection;
import java.util.Random;
import java.util.Scanner;
import java.util.ArrayList;
import java.util.List;
public class randomString {
private static final Exception OutException = new Exception("超出范围");
public static void main(String[] args) {
// TODO Auto-generated method stub
try {
Scanner input = new Scanner(System.in);
System.out.println("请输入数组个数1~29的数字：");
int num = input.nextInt();
List <Integer> size = randSize(num);
List <String> arry = randString(size);
for (int i = 0 ; i < arry.size(); i++) {
System.out.println(arry.get(i));
}
}catch(Exception e) {
System.out.println(e);
}
}
//生产随机长度
public static List<Integer> randSize(int size) throws java.lang.Exception {
//创建数值类 泛型 Integer
List <Integer> sizeOfStr = new ArrayList<Integer>();
//创建 random 对象 randSize
Random randsize = new Random();
//10以内随机值赋值给sizeOfStr数组，个数为size
int k;
if (size >= 30 || size < 1) {
throw OutException;
}
for (int i = 0 ; i < size ; i++) {
do {
k = randsize.nextInt(30);
}while(sizeOfStr.contains(k)||k==0);
sizeOfStr.add(k);
}
System.out.println(sizeOfStr);
return sizeOfStr;
}
//产生字符串
public static List <String> randString(List randSize ) {
List <String> randStr = new ArrayList <String>();
List <Character> randChr = new ArrayList <Character>();
Random randChar = new Random();
for(int i = 0 ; i < randSize.size(); i++) {
//每一组赋值
for(int j = 0 ; j < (int)randSize.get(i); j++ ) {
randChr.add((char)(Math.abs(randChar.nextInt())%(127 -32 +1)+32));
}
randStr.add(randChr.toString());
randChr.clear();
}
randStr.add("done");
return randStr;
}
}
