生成随机字符串的2种方法，请多多指教，还能不能继续优化

// 方法一利用ASCII码：生成10个随机字符串，且长度不大于10，然后添加进List集合

public void testSort2() {

List<String> list = new ArrayList<>();

Random random = new Random();

int temp = 0;

for (int k = 0; k < 10; k++) {

int n;

do {

n = random.nextInt(11);

} while (n == 0);

String str = "";

for (int i = 0; i < n; i++) {

do {

temp = random.nextInt(123);

} while (temp < 48 || (temp > 57) && (temp < 65) || (temp > 90) && (temp < 97));

char ch = (char) temp;

str += ch;

}

list.add(str);

}

System.out.println("排序前：" + list);

Collections.sort(list);

System.out.println("排序后：" + list);

// Collections.sort(list);

// for (String str : list) {

// System.out.print(str + " ");

// }

}

// 方法二利用StringBuilder类：生成10个随机字符串，且长度不大于10，然后添加进List集合

public void testSort3() {

List<String> list = new ArrayList<>();

Random random = new Random();

String strList="abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789";

for (int i = 0; i < 10; i++) {

StringBuilder str = new StringBuilder();

int n;

do {

n = random.nextInt(11);

} while (n == 0);

do {

for (int j = 0; j < n; j++) {

int temp = random.nextInt(62);

str.append(strList.charAt(temp));

}

} while (list.contains(str.toString()));

list.add(str.toString());

}

System.out.println("排序前：" + list);

Collections.sort(list);

System.out.println("排序后：" + list);

}