我们可以在 Java 中创建接口的实例吗？

发布于 2024-10-09 20:17:56 字数 545 浏览 4 评论 0原文

是否可以在 Java 中创建接口的实例？

我在某处读到，使用内部匿名类我们可以这样做，如下所示：

interface Test {
    public void wish();
}

class Main {
    public static void main(String[] args) {
        Test t = new Test() {
            public void wish() {
                System.out.println("output: hello how r u");
            }
        };
        t.wish();
    }
}

cmd> javac Main.java
cmd> java Main
output: hello how r u

这里正确吗？

原文

Is it possible to create an instance of an interface in Java?

Somewhere I have read that using inner anonymous class we can do it as shown below:

interface Test {
    public void wish();
}

class Main {
    public static void main(String[] args) {
        Test t = new Test() {
            public void wish() {
                System.out.println("output: hello how r u");
            }
        };
        t.wish();
    }
}

cmd> javac Main.java
cmd> java Main
output: hello how r u

Is it correct here?

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时光是把杀猪刀 2024-10-16 20:17:56

你永远无法在java中实例化接口。但是，您可以通过接口的类型来引用实现接口的对象。例如，

public interface A
{
}
public class B implements A
{
}

public static void main(String[] args)
{
    A test = new B();
    //A test = new A(); // wont compile
}

您上面所做的是创建一个实现该接口的匿名类。您正在创建一个匿名对象，而不是接口测试类型的对象。

You can never instantiate an interface in java. You can, however, refer to an object that implements an interface by the type of the interface. For example,

public interface A
{
}
public class B implements A
{
}

public static void main(String[] args)
{
    A test = new B();
    //A test = new A(); // wont compile
}

What you did above was create an Anonymous class that implements the interface. You are creating an Anonymous object, not an object of type interface Test.

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落日海湾 2024-10-16 20:17:56

是的，你的例子是正确的。匿名类可以实现接口，这是我能想到的唯一一次您会看到一个类实现不带“implements”关键字的接口。在这里查看另一个代码示例：

interface ProgrammerInterview {
    public void read();
}

class Website {
    ProgrammerInterview p = new ProgrammerInterview() {
        public void read() {
            System.out.println("interface ProgrammerInterview class implementer");
        }
    };
}

这工作正常。取自此页面：

http://www.programmerinterview。 com/index.php/java-questions/anonymous-class-interface/

Yes, your example is correct. Anonymous classes can implement interfaces, and that's the only time I can think of that you'll see a class implementing an interface without the "implements" keyword. Check out another code sample right here:

interface ProgrammerInterview {
    public void read();
}

class Website {
    ProgrammerInterview p = new ProgrammerInterview() {
        public void read() {
            System.out.println("interface ProgrammerInterview class implementer");
        }
    };
}

This works fine. Was taken from this page:

http://www.programmerinterview.com/index.php/java-questions/anonymous-class-interface/

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