接口

//接口
public interface Converter {
    int printInt (String s);
}

//测试类
public class ConveterDemo {
    public static void main(String[] args) {
        useConverter(s -> Integer.parseInt(s));//555

        useConverter(Integer::parseInt);//555
    }

    private static void useConverter(Converter c){
        int number = c.printInt("555");
        System.out.println(number);
    }

//接口
public interface Printer {
    void printUpperCase(String s);
}
//执行类
public class PrintString {
    public void printUpper(String s) {
        String s1 = s.toUpperCase();
        System.out.println(s1);
    }
}
//测试类
public class PrintStringDemo {
    public static void main(String[] args) {
        usePrinter(s -> System.out.println(s.toUpperCase()));

        PrintString printString = new PrintString();
        usePrinter(printString::printUpper);
    }

    private static void usePrinter(Printer p){
        p.printUpperCase("HelloWorld");

    }
}

//接口
public interface MyString {
    String mySubString(String s, int x, int y);
}
//测试类
public class MyStringDemo {
    public static void main(String[] args) {
        useMyString((s, x, y) -> s.substring(x,y));

        useMyString(String::substring);
    }

    private static void useMyString(MyString ms){
        String s = ms.mySubString("HelloWorld", 3, 6);
        System.out.println(s);
    }
}

//接口
public interface StudentBuilder {
    Student build(String s,int age);
}
//学生类
public class Student {
    private String name;
    private int age;

    public Student() {
    }

    public Student(String name, int age) {
        this.name = name;
        this.age = age;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public int getAge() {
        return age;
    }

    public void setAge(int age) {
        this.age = age;
    }
}
//测试类
public class StudentBuilderDemo {
    public static void main(String[] args) {
        useStudentBuilder((String name,int age)->{
            return new Student(name,age);
        });

        useStudentBuilder(Student::new);
    }

    private static void useStudentBuilder(StudentBuilder sb) {
        Student s = sb.build("王冰冰", 25);
        System.out.println(s.getName() + "," + s.getAge());
    }
}

public class RunnableDemo {
    public static void main(String[] args) {
        startThread(new Runnable() {
            @Override
            public void run() {
                System.out.println(Thread.currentThread().getName()+"线程启动了");
            }
        });

        startThread(()->System.out.println(Thread.currentThread().getName()+"线程启动了"));
    }

    private static void startThread(Runnable r){
        new Thread(r).start();
    }
}