JDK1.8_Functional Interface

Functional interface

接口只有一个抽象方法,称之为函数式接口
该接口被@FunctionalInterface修饰
@FunctionalInterface
public interface Comparator<T> {
    
    

Functional interface as method parameter

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    public static void main(String[] args) {
    
    
        //1.匿名内部类
        aaa(new Runnable() {
    
    
            @Override
            public void run() {
    
    
                System.out.println(Thread.currentThread().getName() + "线程启动了");
            }
        });
        //2.lambda表达式
        aaa(()-> System.out.println(Thread.currentThread().getName()+"线程启动了"));
    }

    //函数式接口作为方法的形参
    private static void aaa(Runnable runnable) {
    
    
        new Thread(runnable).start();
    }

Functional interface as method return value

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    public static void main(String[] args) {
    
    
        ArrayList<String> list = new ArrayList<>();
        list.add("ffff");
        list.add("ffgdggdfgdfgfdfff");
        list.add("f");
        list.add("fffffsdfg");
        System.out.println("排序前:" + list);
        Collections.sort(list, getComparator());
        System.out.println("排序后:" + list);
    }

    //函数式接口
    private static Comparator<String> getComparator() {
    
    
        //1.重写接口方法
      Comparator<String> comparator = new Comparator<String>() {
    
    
            @Override
            public int compare(String o1, String o2) {
    
     //升序
                return o2.length() - o1.length();//降序
            }
        };
        return comparator;
 
        /**
         * 2.匿名内部类
         */
      return new Comparator<String>() {
    
    
            @Override
            public int compare(String o1, String o2) {
    
    
                return o2.length() - o1.length();//降序
            }
        };
        /**
         * 3.lambda表达式
         */
        return ( o1, o2)-> o2.length() - o1.length();//降序
    }

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Origin blog.csdn.net/weixin_47785112/article/details/109261889