java8+stream+remove_java8 数据集过滤removeIf和filter

http://www.cnblogs.com/tiandi/p/11185236.html

对象如下，需求：只要30岁以下的人

//求职者的实体类

public class Person {

private String name;//姓名

private Integer age;//年龄

private String gender;//性别

...

//省略构造方法和getter、setter方法

...

//重写toString，方便观看结果

@Override

public String toString() {

return "Person{" +

"name='" + name + ''' +

", age=" + age +

", gender='" + gender + ''' +

'}';

}

}

1、使用Iterator的传统写法

Collection collection = new ArrayList();

collection.add(new Person("张三", 22, "男"));

collection.add(new Person("李四", 19, "女"));

collection.add(new Person("王五", 34, "男"));

collection.add(new Person("赵六", 30, "男"));

collection.add(new Person("田七", 25, "女"));

//过滤30岁以上的求职者

Iterator iterator = collection.iterator();

while (iterator.hasNext()) {

Person p = iterator.next();

if (p.getAge() >= 30)

iterator.remove();

}

System.out.println(collection.toString());//查看结果

2、不用lambda的removeIf写法

Collection collection = new ArrayList();

collection.add(new Person("张三", 22, "男"));

collection.add(new Person("李四", 19, "女"));

collection.add(new Person("王五", 34, "男"));

collection.add(new Person("赵六", 30, "男"));

collection.add(new Person("田七", 25, "女"));

collection.removeIf(new Predicate() {

@Override

public boolean test(Person p) {

return p.getAge()>=30;//过滤30岁以上的求职者

}

});

System.out.println(collection.toString());//查看结果

3、使用lambda的removeIf写法(只有一行了，哈哈)

Collection collection = new ArrayList();

collection.add(new Person("张三", 22, "男"));

collection.add(new Person("李四", 19, "女"));

collection.add(new Person("王五", 34, "男"));

collection.add(new Person("赵六", 30, "男"));

collection.add(new Person("田七", 25, "女"));

collection.removeIf(p -> p.getAge() >= 30);//过滤30岁以上的求职者

System.out.println(collection.toString());//查看结果

4、使用lambda的filter写法

Collection collection = new ArrayList();

collection.add(new Person("张三", 22, "男"));

collection.add(new Person("李四", 19, "女"));

collection.add(new Person("王五", 34, "男"));

collection.add(new Person("赵六", 30, "男"));

collection.add(new Person("田七", 25, "女"));

Stream personStream = collection.stream().filter(p -> p.getAge() < 30)).collect(Collectors.toList());

//由于使用了stream因此后面需要使用.collect(Collectors.toList())转换成list

System.out.println(collection.toString());//查看结果

下面是没有使用lambda的写法

Collection collection = new ArrayList();

collection.add(new Person("张三", 22, "男"));

collection.add(new Person("李四", 19, "女"));

collection.add(new Person("王五", 34, "男"));

collection.add(new Person("赵六", 30, "男"));

collection.add(new Person("田七", 25, "女"));

Stream personStream = collection.stream().filter(new Predicate() {

@Override

public boolean test(Person p) {

return p.getAge() < 30;//只保留男性

}

});

collection = personStream.collect(Collectors.toList());//将Stream转化为List

System.out.println(collection.toString());//查看结果

转载于:https://www.cnblogs.com/tiandi/p/11185236.html

标签：30,collection,removeIf,filter,Person,add,toString,new,java8

来源： https://blog.csdn.net/weixin_30294709/article/details/98189344