list.removeAll()问题

Question

我使用数组查找两个字符串(即str2和str3 )之间的差异。当我使用下面的代码时，它完美地工作，并返回预期的输出。但当我取代

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

预期的输出应该是: al1: 1的内容

但是我得到的输出是: al1：[]的内容

有人能解释我哪里出了问题吗？

提前谢谢。

下面是我的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

要解决问题，请使用String .split()方法

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

String[] s2 = str2.split(",");
String[] s3 = str3.split(",");

for (int i = 0; i < s2.length; i++) {
    al.add(s2[i]);
}

for (int i = 0; i < s3.length; i++) {
    al1.add(s2[i]);
}

al.retainAll(al1);

System.out.println("Size of a1 is " + a1.size());

而且，我认为你想要的是retainAll()，而不是removeAll()。retainAll()是返回boolean，而不是removeAll()的

Answer 2

从我看到的地方:看起来您需要比较用逗号分隔的标记。创建strs的字符串列表(按'，‘拆分)，然后您可以删除类似的字符串，剩余的字符串可以比较不同。