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Java 8 中的炫酷特性和 Java 9 中的新特性 PDF 下载
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主要内容：
从行为进行抽象
“命题： 如何从人员信息的集合里删除所有超过18岁的人？”
Collection<Person> peoples = ...;
for (Person p : peoples){
if (p.getAge() > 18)
?? How do we remove this person ???
}
Collection<Person> peoples = ...;
Iterator<Person> it = peoples.iterator();
while (it.hasNext()) {
Person p = it.next();
if (p.getAge() > 18)
it.remove();
}
Copyright © 2017, Oracle and/or its affiliates. All rights reserved.
进一步抽象
interface Predicate<T> {
boolean test(T t);
}
class Collections {
public static<T>
void removeMatching(Collection<T> coll,
Predicate<T> pred) {
...
} }
The API Designer
Could create methods in the
collection
Copyright © 2017, Oracle and/or its affiliates. All rights reserved.
Collection<Person> peoples = ...;
Collections.removeMatching(peoples,
new Predicate<Person>() {
public boolean test(Person p) {
return p.getAge() > 18; } } });
修改后的实现 But the code to use the new
method would be bloated
Copyright © 2017, Oracle and/or its affiliates. All rights reserved.
使用Java SE 8
• Interface Collection<E> – removeIf(Predicate<? super E> filter)
10
// 简化版
Collection<Person> peoples = ...;
peoples.removeIf(p -> p.getAge() > 18);
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