检查给定类是否是内部类的 Java 程序

原文:https://www . geesforgeks . org/Java-程序检查给定类是否是内部类/

内部类是另一个类的成员，这个类基本上是非静态嵌套类，也就是说，如果一个类在另一个类里面，并且不是静态的，那么这个类被调用就称为内部类。

内部类的类型 :

  1. Nested inner class
  2. Method Local internal class
  3. Anonymous inner class
  4. Static nested class

方法 1:

  1. First, check whether the given class is a nested class.
  2. Further check whether the class is non-static or not.
    • If both conditions are true, then the given class is an inner class.
  3. Now, in order to check whether the given class is a nested class, we use the java.lang.class # getEnclosingclass () method, which returns an instance of class , which represents the directly closed class of the object.
    • If the class is a top-level class, then this method will return null.
    • This means that the method returns null if the class is not nested.
  4. Further use the method to check whether the given class is static.

程序到 检查嵌套的内部类

Java

// Java Program to Check if a Given Class is  an Inner Class

// Importing package where Modifier is defined
import java.lang.reflect.Modifier;

class GFG {

    // Main driver method
    public static void main(String[] args)
    {

        // Creating as GFG class object
        GFG gfg = new GFG();

        // Creating a InnerClass object
        InnerClass innerClass = gfg.new InnerClass();

        // Creating a Static Nested Class object
        StaticNestedClass statNested
            = new StaticNestedClass();

        // getClass() method of an object returns a
        // java.lang.Class instance representing the class
        // of the object
        Class classInstance1 = innerClass.getClass();
        Class classInstance2 = statNested.getClass();

        // Checking if the given classes are nested

        // getEnclosinglClass() of Class instance returns a
        // class object representing the immediate enclosing
        // class of the instance

        boolean isNested1
            = classInstance1.getEnclosingClass() != null;
        // classInstance1() method returns a Class object

        // If the specified class is a top-level class, then
        // it would returns null

        boolean isNested2
            = classInstance2.getEnclosingClass() != null;

        //  Check if the given classes are static

        // getModifiers() method of a class returns the
        // modifiers of the class encoded as an integer

        // Modifiers.isStatic returns true if the class
        // has a static modifier elsereturns false
        boolean isStatic1 = Modifier.isStatic(
            classInstance1.getModifiers());
        boolean isStatic2 = Modifier.isStatic(
            classInstance2.getModifiers());

        // If the given classes are nested and non-static,
        // then given classes are surely inner classes

        // Display message
        System.out.println(
            "Is innerClass an inner class object? : "
            + (isNested1 && !isStatic1));

        // Display message
        System.out.println(
            "Is statNested an inner class object? : "
            + (isNested2 && !isStatic2));
    }

    // Inner Class
    class InnerClass {
    }

    // Static nested class
    static class StaticNestedClass {
    }
}

输出

Is innerClass an inner class object? : true
Is statNested an inner class object? : false

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