java将列表中的元素替换为其他元素

Question

如何用另一个替换list中的元素

例如，我希望所有two都变成one

Answer 1

您可以使用：

Collections.replaceAll(list, "two", "one");

从the documentation：

Replaces all occurrences of one specified value in a list with another. More formally, replaces with newVal each element e in list such that (oldVal==null ? e==null : oldVal.equals(e)). (This method has no effect on the size of the list.)

该方法还返回一个boolean，以指示是否实际进行了任何替换

^{}有更多的static实用方法，您可以在List上使用（例如sort、binarySearch、shuffle等）

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片段

下面展示了Collections.replaceAll的工作原理；它还显示，您还可以替换到null或从null替换：

    List<String> list = Arrays.asList(
        "one", "two", "three", null, "two", null, "five"
    );
    System.out.println(list);
    // [one, two, three, null, two, null, five]

    Collections.replaceAll(list, "two", "one");
    System.out.println(list);
    // [one, one, three, null, one, null, five]

    Collections.replaceAll(list, "five", null);
    System.out.println(list);
    // [one, one, three, null, one, null, null]

    Collections.replaceAll(list, null, "none");
    System.out.println(list);
    // [one, one, three, none, one, none, none]