Java List 交集、差集、并集操作_colleations类取差集-优快云博客

本文详细介绍了如何使用Java List进行差集、交集和并集操作，通过实例展示了如何从一个列表中移除另一个列表的所有元素得到差集，保留共同元素得到交集，并将两者合并形成并集。

 public static void main(String[] args) {
        List<Integer> allSgmt = new ArrayList<>(Arrays.asList(5, 10, 15));
        List<Integer> upKeys = new ArrayList<>(Arrays.asList(5, 10, 15, 20, 25));
        // 差集
        allSgmt.removeAll(upKeys);
        System.out.println("差集: " + allSgmt);
        allSgmt = new ArrayList<>(Arrays.asList(5, 10, 15, 20, 25));
        upKeys = new ArrayList<>(Arrays.asList(5, 10, 15));
        // 交集
        allSgmt.retainAll(upKeys);
        System.out.println("交集: " + allSgmt);
        allSgmt = new ArrayList<>(Arrays.asList(5, 10, 15, 20, 25));
        upKeys = new ArrayList<>(Arrays.asList(5, 10, 15));
        // 并集
        allSgmt.addAll(upKeys);
        System.out.println("并集: " + allSgmt);


        allSgmt = new ArrayList<>(Arrays.asList(5, 10, 15));
        upKeys = new ArrayList<>(Arrays.asList(5, 10, 15, 20, 25));

        List<Integer> allSgmt1 = new ArrayList<>(allSgmt);
        List<Integer> upKeys1 = new ArrayList<>(upKeys);
        // 交集
        allSgmt1.retainAll(upKeys1);
        // 差集
        allSgmt.removeAll(allSgmt1);
        upKeys.removeAll(allSgmt1);
        allSgmt.addAll(upKeys);
        System.out.println("去除相交的部分：" +allSgmt);

    }