java8之lambda表达式入门

@FunctionalInterface
public interface Comparator<T> {
    int compare(T o1, T o2);
}

public void test1_(){
        List<Student> studentList = new ArrayList<Student>(){
            {
                add(new Student("stu1",100.0));
                add(new Student("stu2",97.0));
                add(new Student("stu3",96.0));
                add(new Student("stu4",95.0));
            }
        };
        Collections.sort(studentList,(s1,s2)-> Double.compare(s1.getScore(),s2.getScore()));
        System.out.println(studentList);
    }

public void testThread(){
        new Thread(new Runnable() {
            @Override
            public void run() {
                System.out.println("hello, i am thread!");
            }
        }).start();
    }

@FunctionalInterface
public interface Runnable {
    /**
     * When an object implementing interface <code>Runnable</code> is used
     * to create a thread, starting the thread causes the object‘s
     * <code>run</code> method to be called in that separately executing
     * thread.
     * <p>
     * The general contract of the method <code>run</code> is that it may
     * take any action whatsoever.
     *
     * @see     java.lang.Thread#run()
     */
    public abstract void run();
}

public void testThread_(){
    new Thread(()-> System.out.println("hello, i am thread!")).start();
}

@FunctionalInterface
public interface MyFunctionalInterface {
    public void single(String msg);
}
 
/**
 * 需要单个参数
 */
public static void testOnePar(MyFunctionalInterface myFunctionalInterface){
    myFunctionalInterface.single("msg");
}
/**
     * 一个参数，可以省略参数的括号
     */
    @Test
    public void testOneParameter(){
        testOnePar(x-> System.out.println(x));
    }

/**
     * 需要单个参数
     */
    public static void testOnePar1(Consumer unaryOperator){
        unaryOperator.accept("msg");
    }

public static void test1_() {
    List<String> strLst = new ArrayList<String>() {
        {
            add("adfkjsdkfjdskjfkds");
            add("asdfasdfafgfgf");
            add("public static void main");
        }
    };
    Collections.sort(strLst, String::compareToIgnoreCase);
    System.out.println(strLst);
}

class Father {
    public void greet() {
        System.out.println("Hello, i am function in father!");
    }
}
 
class Child extends Father {
    @Override
    public void greet() {
        Runnable runnable = super::greet;
        new Thread(runnable).start();
    }
}
public static void main(String[] args){
        new Child().greet();
    }

List<String> labels = Arrays.asList("aaa","bbb","ccc","ddd");
Stream<Button> buttonStream = labels.stream().map(Button::new);

<R> Stream<R> map(Function<? super T, ? extends R> mapper);

public class Button extends ButtonBase {
 
        /**
         * Creates a button with the specified text as its label.
         *
         * @param text A text string for its label.
         */
        public Button(String text) {
            super(text);
            initialize();
        }
    }

Button[] buttons1 = buttonStream.toArray(Button[]::new);

<A> A[] toArray(IntFunction<A[]> generator);

public class LambdaTest3 {
 
    @Test
    public void test1_(){
        List<Integer> list = this.asList(ArrayList::new ,1,2,3,4,5);
        list.forEach(System.out::println);
    }
 
    public  <T> List<T> asList(MyCrator<List<T>> creator,T... a){
        List<T> list =  creator.create();
        for (T t : a)
            list.add(t);
        return list;
    }
}
interface MyCrator<T extends List<?>>{
    T create();
}

public static <T> List<T> asList(T... a) {
    return new ArrayList<>(a);
}

public class LambdaTest4 {
    public void doWork1(){
        Runnable runnable = ()->{
            System.out.println(this.toString());
            System.out.println("lambda express run...");
        };
        new Thread(runnable).start();
    }
 
    public void doWork2(){
        Runnable runnable = new Runnable() {
            @Override
            public void run() {
                System.out.println(this.toString());
                System.out.println("anony function run...");
            }
        };
        new Thread(runnable).start();
    }
    public static void main(String[] args) {
        new LambdaTest4().doWork1();
        new LambdaTest4().doWork2();
    }
}

com.java8.lambda.LambdaTest4@74f84cf
lambda express run...
com.java8.lambda.LambdaTest4$1@4295c176
anony function run...

public class Outer {
    public AnnoInner getAnnoInner(int x) {
        int y = 100;
        return new AnnoInner() {
            int z = 100;
 
            @Override
            public int add() {
                return x + y + z;
            }
        };
    }
 
    public AnnoInner AnnoInnergetAnnoInner1(List<Integer> list1) {
        List<Integer> list2 = new ArrayList<>(Arrays.asList(1, 2, 3));
        return ()->{
            list2.add(123);
            int count = 0;
            Iterator<Integer> it = list1.iterator();
            while (it.hasNext()){
                count+=it.next();
            }
            Iterator<Integer> it1 = list2.iterator();
            while (it1.hasNext()){
                count+=it1.next();
            }
            return count;
        };
    }
 
    @Test
    public void test(){
        AnnoInner res = new Outer().AnnoInnergetAnnoInner1(new ArrayList<>(Arrays.asList(1,2,3)));
        System.out.println(res.add());
    }
 
}
 
interface AnnoInner {
    int add();
}

@FunctionalInterface
public interface Comparator<T> {
 
    int compare(T o1, T o2);
 
    boolean equals(Object obj);
 
    default Comparator<T> reversed() {
        return Collections.reverseOrder(this);
    }
 
    default Comparator<T> thenComparing(Comparator<? super T> other) {
        Objects.requireNonNull(other);
        return (Comparator<T> & Serializable) (c1, c2) -> {
            int res = compare(c1, c2);
            return (res != 0) ? res : other.compare(c1, c2);
        };
    }
 
    default <U> Comparator<T> thenComparing(
            Function<? super T, ? extends U> keyExtractor,
            Comparator<? super U> keyComparator)
    {
        return thenComparing(comparing(keyExtractor, keyComparator));
    }
 
    default <U extends Comparable<? super U>> Comparator<T> thenComparing(
            Function<? super T, ? extends U> keyExtractor)
    {
        return thenComparing(comparing(keyExtractor));
    }
 
    default Comparator<T> thenComparingInt(ToIntFunction<? super T> keyExtractor) {
        return thenComparing(comparingInt(keyExtractor));
    }
 
    default Comparator<T> thenComparingLong(ToLongFunction<? super T> keyExtractor) {
        return thenComparing(comparingLong(keyExtractor));
    }
 
    default Comparator<T> thenComparingDouble(ToDoubleFunction<? super T> keyExtractor) {
        return thenComparing(comparingDouble(keyExtractor));
    }
 
    public static <T extends Comparable<? super T>> Comparator<T> reverseOrder() {
        return Collections.reverseOrder();
    }
 
    @SuppressWarnings("unchecked")
    public static <T extends Comparable<? super T>> Comparator<T> naturalOrder() {
        return (Comparator<T>) Comparators.NaturalOrderComparator.INSTANCE;
    }
 
    public static <T> Comparator<T> nullsFirst(Comparator<? super T> comparator) {
        return new Comparators.NullComparator<>(true, comparator);
    }
 
    public static <T> Comparator<T> nullsLast(Comparator<? super T> comparator) {
        return new Comparators.NullComparator<>(false, comparator);
    }
 
    public static <T, U> Comparator<T> comparing(
            Function<? super T, ? extends U> keyExtractor,
            Comparator<? super U> keyComparator)
    {
        Objects.requireNonNull(keyExtractor);
        Objects.requireNonNull(keyComparator);
        return (Comparator<T> & Serializable)
            (c1, c2) -> keyComparator.compare(keyExtractor.apply(c1),
                                              keyExtractor.apply(c2));
    }
 
    public static <T, U extends Comparable<? super U>> Comparator<T> comparing(
            Function<? super T, ? extends U> keyExtractor)
    {
        Objects.requireNonNull(keyExtractor);
        return (Comparator<T> & Serializable)
            (c1, c2) -> keyExtractor.apply(c1).compareTo(keyExtractor.apply(c2));
    }
 
    public static <T> Comparator<T> comparingInt(ToIntFunction<? super T> keyExtractor) {
        Objects.requireNonNull(keyExtractor);
        return (Comparator<T> & Serializable)
            (c1, c2) -> Integer.compare(keyExtractor.applyAsInt(c1), keyExtractor.applyAsInt(c2));
    }
 
    public static <T> Comparator<T> comparingLong(ToLongFunction<? super T> keyExtractor) {
        Objects.requireNonNull(keyExtractor);
        return (Comparator<T> & Serializable)
            (c1, c2) -> Long.compare(keyExtractor.applyAsLong(c1), keyExtractor.applyAsLong(c2));
    }
 
    public static<T> Comparator<T> comparingDouble(ToDoubleFunction<? super T> keyExtractor) {
        Objects.requireNonNull(keyExtractor);
        return (Comparator<T> & Serializable)
            (c1, c2) -> Double.compare(keyExtractor.applyAsDouble(c1), keyExtractor.applyAsDouble(c2));
    }
}

public class LambdaTest5 implements myInterface1, myInterface2 {
    @Override
    public void getName() {
        myInterface1.super.getName();
    }
 
    public static void main(String[] args) {
        new LambdaTest5().getName();
    }
}
 
interface myInterface1 {
    default void getName() {
        System.out.println("myInterface1 getName");
    }
 
    ;
}
 
interface myInterface2 {
    default void getName() {
        System.out.println("myInterface2 getName");
    }
}