为什么不能在Java中将类声明为静态类？

Z时代
2024-01-10
分类：问答

回答：

只有嵌套的类可以是静态的。这样，你可以使用嵌套类而无需外部类的实例。

class OuterClass{
    public static class StaticNestedClass{
    }
    public class InnerClass{
    }
    public InnerClass getAnInnerClass(){
        return new InnerClass();
    }
    //This method doesn't work
    public static InnerClass getAnInnerClassStatically(){
        return new InnerClass();
    }
}
class OtherClass{
    //Use of a static nested class:
    private OuterClass.StaticNestedClass staticNestedClass = new OuterClass.StaticNestedClass();
    //Doesn't work
    private OuterClass.InnerClass innerClass = new OuterClass.InnerClass();
    //Use of an inner class:
    private OuterClass outerclass= new OuterClass();
    private OuterClass.InnerClass innerClass2 = outerclass.getAnInnerClass();
    private OuterClass.InnerClass innerClass3 = outerclass.new InnerClass();
}