浅析Java8新特性Lambda表达式和函数式接口

  // 启动一个线程，不使用Lambda表达式
  new Thread(new Runnable() {
    @Override
    public void run() {
      System.out.println("启动一个线程");
    }
  }).start();
  //使用Lambda表达式,只需要一行代码
  new Thread(() -> System.out.println("启动一个线程")).start();

  // 实现Runnable接口（无参，无返回）
  Runnable r = () -> System.out.println("hello lambda");

  //Consumer接口（一个参数，无返回值），之后会提到
  //第一种，小括号不省略
  Consumer<String> c = (x) -> System.out.print(x);
  c.accept("hello");
  //小括号省略
  Consumer<String> c1 = x -> System.out.print(x);
  c1.accept("hello")

//Comparator接口
  //多条语句
  Comparator<Integer> comparator = (x,y) ->{
    System.out.println("hello");
    return Integer.compare(x, y);
  };
  //一条语句
  Comparator<Integer> comparator2 = (x,y) -> Integer.compare(x, y);
  System.out.println(comparator2.compare(23, 22));

//Consumer<T> 消费型接口
  @Test
  public void test1(){
    Consumer<String> c = (x) -> System.out.println("hello:"+x+"!");
    c.accept("Java");
  }
  // Supplier<T> 供给型接口
  @Test
  public void test2(){
    Supplier<String> s = () -> "hello,beautiful girl";
    String str = s.get();
    System.out.println(str);
  }
  //Function<T,R> 函数性接口
  @Test
  public void test3(){
    Function<String, Integer> f= (x) -> x.length();
    Integer len = f.apply("hello");
    System.out.println(len);
  }
  //Predicate<T> 断言型接口
  @Test
  public void test4(){
    Predicate<String> p = (x) -> x.length()>5;
    boolean b = p.test("hello Java");
    System.out.println(b);
  }