版权声明:本文为博主原创文章,未经博主允许不得转载。 https://blog.csdn.net/u012865381/article/details/85071753
代替匿名内部类
before
@Test
public void oldRunable() {
new Thread(new Runnable() {
@Override
public void run() {
System.out.println("The old runable now is using!");
}
}).start();
}
after
@Test
public void runable() {
new Thread(() -> System.out.println("It's a lambda function!")).start();
}
output
The old runable now is using!
It's a lambda function!
对集合进行迭代
@Test
public void iterTest() {
List<String> languages = Arrays.asList("java","scala","python");
//before java8
for(String each:languages) {
System.out.println(each);
}
//after java8
languages.forEach(x -> System.out.println(x));
languages.forEach(System.out::println);
}
实现map
@Test
public void mapTest() {
List<Double> cost = Arrays.asList(10.0, 20.0,30.0);
cost.stream().map(x -> x + x*0.05).forEach(x -> System.out.println(x));
}
reduce的两个参数,第一个是上一层执行的中间结果,第二个参数是上一步执行的结果,传输到本步骤
实现map与reduce
@Test
public void mapReduceTest() {
List<Double> cost = Arrays.asList(10.0, 20.0,30.0);
double allCost = cost.stream().map(x -> x+x*0.05).reduce((sum,x) -> sum + x).get();
System.out.println(allCost);
}
与函数式接口Predicate配合
public static void filterTest(List<String> languages, Predicate<String> condition) {
languages.stream().filter(x -> condition.test(x)).forEach(x -> System.out.println(x + " "));
}
public static void main(String[] args) {
List<String> languages = Arrays.asList("Java","Python","scala","Shell","R");
System.out.println("Language starts with J: ");
filterTest(languages,x -> x.startsWith("J"));
System.out.println("\nLanguage ends with a: ");
filterTest(languages,x -> x.endsWith("a"));
System.out.println("\nAll languages: ");
filterTest(languages,x -> true);
System.out.println("\nNo languages: ");
filterTest(languages,x -> false);
System.out.println("\nLanguage length bigger three: ");
filterTest(languages,x -> x.length() > 4);
}
output
Language starts with J:
Java
Language ends with a:
Java
scala
All languages:
Java
Python
scala
Shell
R
No languages:
Language length bigger three:
Python
scala
Shell