java threads multi thread multthread

public class ThreadExample2 implements Runnable {
public static void main(String[] argv) {
        Thread t = new Thread(new ThreadExample2()); // 產生Thread物件
        t.start(); // 開始執行Runnable.run();
        for (;;) {
            System.out.println("Main Thread");
        }
    }
synchronized static public void syncMethod() {…}
}

public class Animal {    public String moveMethod() {        return "Unspecified";    }}
public class Bird extends Animal {    public String moveMethod() {        return "Fly";    }}
public class Dog extends Animal {    public String moveMethod() {        return "run";    }}
public class Fish extends Animal {    public String moveMethod() {        return "swim";    }}

public class InheritanceExample {
    public static void main(String[] argv) {
        Animal a1, a2, a3, a4;
        Bird b;
        Dog d;
        Fish f;
        a2 = a1 = new Animal();
        b = new Bird();
        d = new Dog();
        f = new Fish();
        System.out.println(a1.moveMethod());
        System.out.println(b.moveMethod());
        System.out.println(d.moveMethod());
        System.out.println(f.moveMethod());
        a1 = b; // Correct, we call this upcasting
        b = a1; // Compile Error, type not compatible
        b = (Bird)a1; // downcasting, Compile Correct
        a2 = b; // Correct,we call this upcasting
        d = a2; // Compile Error, type not compatible
        d = (Dog)a2; // Compile Correct, but runtime error
    }
}

<< thread >>

public class ThreadExample2 implements Runnable {
    public void run() { // implements Runnable run()
        System.out.println("Here is the starting point of Thread.");
        for (;;) { // infinite loop to print message
            System.out.println("User Created Thread");
        }
    }
    public static void main(String[] argv) {
        Thread t = new Thread(new ThreadExample2()); // 產生Thread物件
        t.start(); // 開始執行Runnable.run();
        for (;;) {
            System.out.println("Main Thread");
        }
    }
}