Java泛型

public class GenericTest {

    public static void main(String[] args) {

        Box<String> name = new Box<String>("corn");
        System.out.println("name:" + name.getData());
        Box<Integer> number=new Box<Integer>(20);
        System.out.println("number:"+number.getData());
    }

}
class Box<T>   //引入一个类型变量T，用<>括起来，并放在类名的后面，同时泛型类可以有多个类型变量。
{
    private T data;
    public Box() {

    }
    public Box(T data) {
        this.data = data;
    }
    public T getData() {
        return data;
    }
} 

interface Show<T,U>{
    void show(T t,U u);
}

class ShowTest implements Show<String,Date>{
    @Override
    public void show(String str,Date date) {
        System.out.println(str);
        System.out.println(date);
    }
}

public static void main(String[] args) throws ClassNotFoundException {
    String str=get("Hello", "World");
    System.out.println(str);
}

public static <T, U> T get(T t, U u) {
    if (u != null)
        return t;
    else
        return null;
}