使用Java 8迭代和过滤两个列表 [英] iterating and filtering two lists using java 8

问题描述

我想迭代两个列表并获取新的过滤列表，该列表将具有第二个列表中不存在的值.有人可以帮忙吗?

I want to iterate two lists and get new filtered list which will have values not present in second list. Can anyone help?

我有两个列表-一个是字符串列表，另一个是MyClass对象列表.

I have two lists - one is list of strings, and the other is list of MyClass objects.

List<String> list1;
List<MyClass> list2;

MyClass {

    MyClass(String val)
    {
        this.str = val;
    }

     String str;
     ...
     ...
}

我想要基于->筛选字符串列表，请检查第二个列表以查找其值不在list1中的元素(abc).

I want filtered list of strings based on -> check second list for elements (abc) whose values not present in list1.

List<String> list1 = Arrays.asList("abc", "xyz", "lmn");

List<MyClass> list2 = new ArrayList<MyClass>();

MyClass obj = new MyClass("abc");
list2.add(obj);
obj = new MyClass("xyz");
list2.add(obj);

现在我想要新的过滤列表->它将具有值=>"lmn".即list2中不存在其元素在list1中的值.

Now I want new filtered list -> which will have value => "lmn". i.e. values not present in list2 whose elements are in list1.

推荐答案

这可以通过以下方法实现...

this can be achieved using below...

 List<String> unavailable = list1.stream()
                            .filter(e -> !list2.contains(e))
                            .collect(Collectors.toList());

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