Java8函数式接口的基础学习教程

public class RunnableDemo {
	public static void main(String[] args) {
		//在主方法中凋用startThread方法
		
		//匿名内部类
		startThread(new Runnable() {
			
			@Override
			public void run() {
				System.out.println(Thread.currentThread().getName() + " 线程启动");
			}
		});
		
		//Lambda
		startThread(() -> System.out.println(Thread.currentThread().getName() + " 线程启动"));
		
	}
	
	private static void startThread(Runnable r) {//方法参数Runnable是一个凾数式接口
//		Thread t = new Thread(r);
//		t.start();
		new Thread(r).start();
	}
}

public class ComparatorDemo {

	public static void main(String[] args) {
		//构造使用场景 根据字符串长度
		//定义集合，存储字符串元素
		ArrayList<String> array = new ArrayList<String>();
		array.add("Collin");
		array.add("Leon");
		array.add("Pi");
		array.add("123");
		array.add("878");
		
		System.out.println("排序前: " + array);
		
		Collections.sort(array);
		System.out.println("排序后: " + array);
		Collections.sort(array, getComparator());
		System.out.println("排序后: " + array);
	}

        private static Comparator<String> getComparator(){
                //匿名内部类的方式实现
                //根据长度去排序
//		Comparator<String > comp = new Comparator<String>() {
//				
//			@Override
//			public int compare(String o1, String o2) {
//				return o1.length() - o2.length();
//			}
//		};
//		return comp;

                //改进
//		return new Comparator<String>() {
//				
//		@Override
//		public int compare(String o1, String o2) {
//			return o1.length() - o2.length();
//			}
//		};

                //改进为Lambda表达式
//		return ((String s1, String s2) -> {
//			return s1.length()-s2.length();
//		});

                //优化
                return (s1,s2) -> s1.length()-s2.length();
        }
}

public class SupplierDemo {
	public static void main(String[] args) {
//		String s = getstring(() -> {
//			return "你好Java";
//		});
		//优化
		String s = getstring(() -> "略略略");
		System.out.println(s);
		
		Integer i = getInteger(() -> 9920);
		System.out.println(i);
		
	}
	//定义一个方法，返回一个int数据
	private static Integer getInteger(Supplier<Integer> sup) {
		return sup.get();
	}
	//定义一个方法，返回一个String数据
	private static String getstring(Supplier<String> sup) {
		return sup.get();
	}
}

	public static void main(String[] args) {
		operatorString("Leo1", (String s) ->{
			System.out.println(s);
		});
		//优化
		operatorString("Leo2", s -> System.out.println(s));
		//方法引用
		operatorString("Leo3", System.out::println);

		operatorString("Leo4", s -> System.out.println(new StringBuilder(s).reverse()));
		System.out.println("--------------");
		
		operatorString("Leon5", s -> System.out.println(s),s -> System.out.println(new StringBuilder(s).reverse()));
		
	}
	//定一个方法，用不同的方式消费同一个一个字符串数据俩次
	private static void operatorString(String name, Consumer<String> con1,Consumer<String> con2) {
//		con1.accept(name);
//		con2.accept(name);
		con1.andThen(con2).accept(name);
		//先消费name，再con2
	}
	
	//定一个方法，消费一个字符串数据
	private static void operatorString(String name, Consumer<String> con) {
		con.accept(name);
	}

}

public class ConsumerTest {
	public static void main(String[] args) {
		String[] strArray= {"林青霞,30","张曼玉,35","王祖贤,33"};
		
		printInfo(strArray, (String str) ->{
			String name = str.split(",")[0];
			System.out.print("Name: " + name);
		},(String str) -> {
			int age =Integer.parseInt(str.split(",")[1]);
			System.out.println(" ,Age: " + age);
		});
		System.out.println("-------------------");
		//改进
		printInfo(strArray, 
				str -> System.out.print("Name: "+ str.split(",")[0]), 
				str -> System.out.println(" ,Age: " + Integer.parseInt(str.split(",")[1]))
				);
	}
	
	private static void printInfo(String[] strArray, Consumer<String> con1, Consumer<String> con2) {
		for(String str : strArray) {
			con1.andThen(con2).accept(str);
		}
	}
}

public class PredicateTest {
	public static void main(String[] args) {
		String[] strArray= {"林青霞,30","柳岩,34", "张曼玉,35","貂蝉,31","王祖贤,33"};
		
		ArrayList<String> array = myFilter(strArray,
				s -> s.split(",")[0].length() > 2,
				s -> Integer.parseInt(s.split(",")[1]) > 33);
		for (String str : array) {
			System.out.println(str);
		}
	}
	//通过Predicate接口的拼装将符合要求的字符串筛选到集合ArrayList中
	private static ArrayList<String> myFilter(String[] strArray, Predicate<String> pre1, Predicate<String> pre2){
		//定义一个集合
		ArrayList<String> array = new ArrayList<String>();
		
		//遍历数组
		for (String str : strArray) {
			if(pre1.and(pre2).test(str)) {
				array.add(str);
			}
		}
		return array;
	}
}

public class FunctionTest {

	public static void main(String[] args) {
		String s ="林青霞,30";
		
		convert(s, ss -> s.split(",")[1], ss -> Integer.parseInt(ss), i -> i + 70);
	}
	
	private static void convert(String s, Function<String, String> fun1, Function<String, Integer> fun2, Function<Integer, Integer> fun3) {
		int i = fun1.andThen(fun2).andThen(fun3).apply(s);
		System.out.println(i);
		
	}

}