java - list.removeAll() 的问题

Question

我使用数组列表来查找两个字符串(即 str2 和 str3)之间的差异。当我使用下面的代码时，它工作正常并返回预期的输出。但当我更换时

str2 = #19, 6th cross, 7th main road, townname, cityname-560036
str3 = #19, 6th cross, 17th main road, townname, cityname-560036  

预期输出应该是:al1的内容:[1]

但我得到的输出是:al1的内容:[]

谁能解释一下我哪里出错了？

提前致谢。

这是我的 doPost 方法:

protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException
{
            str2="Hello";
    str3="Hallo";
    System.out.println("-------");
    System.out.println("This is first string:"+""+str2);
    System.out.println("This is second string:"+""+str3);


    ArrayList al = new ArrayList();
    ArrayList al1=new ArrayList(); 

      System.out.println("Initial size of al: " + al.size());

      // add elements to the array list
      for (int i = 0;i < str2.length(); i++)
        {
            al.add(str2.charAt(i));
        }
      System.out.println("Size of al after additions: " + al.size());

      // display the array list
      System.out.println("Contents of al: " + al);



      for (int i = 0;i < str3.length(); i++)
        {
            al1.add(str3.charAt(i));
        }

      System.out.println("Contents of al1: " + al1);

      System.out.println("Size of al1 after additions: " + al1.size());
        boolean hg=al1.removeAll(al);
        System.out.println("Remove All:"+hg);


      System.out.println("Contents of al: " + al);
      System.out.println("Contents of al1: " + al1);

}

Answer 1

这里“#19”已经有了字符“1”，因此当您调用“全部删除”时，所有“1”都会被删除，包括您希望保留的那个。我认为你应该迭代字符并提取差异，否则比较不会很准确。