java第三季随机字符串2老师留作业

package testsStringSort;

import java.util.ArrayList;
import java.util.Collections;
import java.util.List;
import java.util.Random;

public class Sort {

List<String> stringList=new ArrayList<String>();
public static String getRandomString(int length)  { //length表示生成字符串的长度
    String base = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789";   
    Random random = new Random();   
    StringBuffer sb = new StringBuffer();   
    for (int i = 0; i < length; i++) {   
        int number = random.nextInt(base.length());   
        sb.append(base.charAt(number));   
    }   
    return sb.toString();   
 }  
public void testsort1() throws Exception{
    Random random=new Random();
    String k;
    for(int i=0;i<10;i++){
    do{
         int length=random.nextInt(10)+1;

         k=Sort.getRandomString(length);

    }
    while(stringList.contains(k) );

        stringList.add(k);
        System.out.println("成功添加字符串："+k);

        }

    System.out.println("------------------排序前-----------------");
    for (String string : stringList) {
        System.out.println("元素："+string);
    }
   Collections.sort(stringList);
   System.out.println("------------------排序后-----------------");
    for (String string : stringList) {
        System.out.println("元素："+string);
    }
}

public static void main(String[] args) throws Exception {
    Sort st=new Sort(); 
    st.testsort1();

}

}