Java：泛型方法、泛型类、泛型接口、类型通配符-创新互联

• • 泛型方法
  • 泛型类
  • 泛型接口
  • 类型通配符

要求：

JDK >= 1.5

package com.example.demo;

import java.io.IOException;

public class Demo {// 泛型方法
    public staticvoid 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);
    }
}

使用泛型，可以不做类型强制转换

package demo;

public class Box{private T value;

    public void set(T value) {this.value = value;
    }

    public T get() {return this.value;
    }

    public static void main(String[] args) {Boxbox = new Box<>();
        box.set("Tom");
        String value = box.get();
        System.out.println(value);
    }
}

package demo;

interface IBox{void set(T value);

    T get();
}


class Boximplements IBox{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) {Boxbox = new Box<>();
        box.set("Tom");
        String value = box.get();
        System.out.println(value);
    }
}

public class Demo {public static void main(String[] args) {Boxbox = new Box<>();

        printBox(box);
    }

    public static void printBox(IBoxbox) {System.out.println(box);
    }
}

参考
https://www.runoob.com/java/java-generics.html
Java学习路线-7：泛型
聊一聊-JAVA 泛型中的通配符 T，E，K，V，？

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