Java 有没有办法用流比较两个列表？

Is there a way of comparing two Lists with streaming?

提问by Hasholef

I have a class called MyClassthat contains couple of members and one of them is myString:

我有一个名为的类MyClass，其中包含几个成员，其中一个是myString：

public class MyClass{
  //...
  private String myString;
}

Now, I have a collection of MyClassand another collection of String.

现在，我有一个集合MyClass和另一个集合String。

My question is:

我的问题是：

How to compare those two collections with streaming? Is that possible?

如何将这两个集合与流媒体进行比较？那可能吗？

采纳答案by Marlon Bernardes

You could map a list of MyClassto a List of Strings and then compare them normally:

您可以将一个列表映射MyClass到一个字符串列表，然后正常比较它们：

List<String> anotherList = listOfMyClass.stream()
      .map(MyClass::getMyString)  //Assuming that you have a getter for myString
      .collect(Collectors.toList()); 

You could also join all the elements of the list in a single Stringand compare them directly. This will only work if the order of the elements should be the same in both lists. Examples below:

您还可以将列表中的所有元素合并成一个String并直接进行比较。这仅在两个列表中元素的顺序应该相同时才有效。下面的例子：

    final String joinSeparator = ", ";

    String firstResult = stringList
            .stream()
            .collect(Collectors.joining(joinSeparator));

    String secondResult = myClassList
            .stream()
            .map(MyClass::getMyString)
            .collect(Collectors.joining(joinSeparator));

    //Just compare them using equals:
    System.out.println(firstResult.equals(secondResult));