Java：泛型方法、泛型类、泛型接口、类型通配符

package com.example.demo;
import java.io.IOException;
public class Demo {
    // 泛型方法
    public static <T> void printT(T value) {
        System.out.println(value);
    }
    public static void printObject(Object value) {
        System.out.println(value);
    }
    public static void main(String[] args) throws IOException {
        Demo.printT("Tom");
        Demo.printT(23);
        Demo.printObject("Tom");
        Demo.printObject(23);
    }
}

package demo;
public class Box {
    private Object value;
    public void set(Object value) {
        this.value = value;
    }
    public Object get() {
        return this.value;
    }
    public static void main(String[] args) {
        Box box = new Box();
        box.set("Tom");
        String value = (String) box.get();
        System.out.println(value);
    }
}

package demo;
public class Box<T> {
    private T value;
    public void set(T value) {
        this.value = value;
    }
    public T get() {
        return this.value;
    }
    public static void main(String[] args) {
        Box<String> box = new Box<>();
        box.set("Tom");
        String value = box.get();
        System.out.println(value);
    }
}

package demo;
interface IBox<T> {
    void set(T value);
    T get();
}
class Box<T> implements IBox<T> {
    private T value;
    @Override
    public void set(T value) {
        this.value = value;
    }
    @Override
    public T get() {
        return this.value;
    }
}
public class Demo {
    public static void main(String[] args) {
        Box<String> box = new Box<>();
        box.set("Tom");
        String value = box.get();
        System.out.println(value);
    }
}

public class Demo {
    public static void main(String[] args) {
        Box<String> box = new Box<>();
        printBox(box);
    }
    public static void printBox(IBox<?> box) {
        System.out.println(box);
    }
}