我这个里面的contains没有改写equals方法，因为List里面的对象是String类，会不会存在问题呢

package collection_map_demon;

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

public class String_test {
 public List<String> StringList;
 private Scanner console;
 public String_test()
 {
  StringList = new ArrayList<String>();
  
 }
 public void setTest()
 {
  Random random = new Random();
  StringBuffer[] slist = new StringBuffer[10];
  for(int j=0;j<10;j++)
  {
   
   int i = random.nextInt(10)+1;
    slist[j] = new StringBuffer(i);
   String base = "0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ";
   String s;
   do
   {
   for(int k=0;k<i;k++)
   {
    int number = random.nextInt(base.length());
    //slist[j].setCharAt(k,base.charAt(number));
    slist[j].append(base.charAt(number));
   }
   s = slist[j].toString();
   }while(StringList.contains(s));
   StringList.add(s);
  }
  System.out.println("--------------------排序前-------------------------");
  for(String s :StringList)
  {
   System.out.println(s);
  }
  System.out.println("--------------------排序后--------------------------");
  Collections.sort(StringList);
  for(String s : StringList)
  {
   System.out.println(s);
  }
  
 }
 public static void main(String[] args) {
  String_test t = new String_test();
  t.setTest();
 }
}