List去重有几种方式

1、for循环添加去重

2、for 双循环去重

3、for 双循环重复坐标去重

4、Set去重

5、stream流去重

1、for循环添加去重

List<String> oldList = new ArrayList<>();oldList.add("张三");oldList.add("张三");oldList.add("李四");oldList.add("王五");oldList.add("赵六");List<Object> newList = Lists.newArrayList();for (String name : oldList) {if (!newList.contains(name)){newList.add(name);}}System.out.println("原本的集合原素"+oldList);System.out.println("去重后的集合"+newList);// An highlighted block
var foo = 'bar';

打印结果如下：

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2、for 双循环去重

@Testpublic void test77() {List<String> oldList = new ArrayList<>();oldList.add("张三");oldList.add("张三");oldList.add("李四");oldList.add("王五");oldList.add("赵六");for (int i = 0; i < oldList.size(); i++) {for (int j = oldList.size() - 1; j > i; j--) {if (oldList.get(j).equals(oldList.get(i))) {oldList.remove(j);}}}System.out.println("原本的集合元素：" + oldList);}}

打印结果如下：

在这里插入图片描述

3、for 双循环重复坐标去重

@Testvoid contextLoads4() {List<String> oldList = new ArrayList<>();oldList.add("张三");oldList.add("张三");oldList.add("李四");oldList.add("王五");oldList.add("赵六");List<String> newList = Lists.newArrayList();newList.addAll(oldList);for (String name : newList) {if (oldList.indexOf(name) != oldList.lastIndexOf(name)) {oldList.remove(oldList.lastIndexOf(name));}}System.out.println("原本的集合原素"+oldList);}// An highlighted block
var foo = 'bar';

打印结果如下：

在这里插入图片描述

4、Set去重

@Testvoid contextLoads5() {List<String> oldList = new ArrayList<>();oldList.add("张三");oldList.add("张三");oldList.add("李四");oldList.add("王五");oldList.add("赵六");List<String> newList = Lists.newArrayList(new HashSet(oldList));System.out.println("原本的集合原素"+newList);}// An highlighted block
var foo = 'bar';

打印结果如下：

在这里插入图片描述

5、stream流去重

@Testvoid contextLoads5() {List<String> oldList = new ArrayList<>();oldList.add("张三");oldList.add("张三");oldList.add("李四");oldList.add("王五");oldList.add("赵六");List<String> collect = oldList.stream().distinct().collect(Collectors.toList());System.out.println("原本的集合原素"+collect);}// An highlighted block
var foo = 'bar';