Java中的类 isAssignableFrom() 方法及示例

Java.lang.Class 类的isAssignableFrom()方法用于检查指定类的对象是否兼容分配给该类的实例。如果两个类相同，或者指定的类是超类或超接口，它将兼容。如果指定类的对象可以转换为此类的实例，则该方法返回 true。否则返回 false。

句法：

public boolean isAssignableFrom(Class class)

参数：此方法接受类作为参数，该类是要检查其对象与此 Class 实例的兼容性的指定类。

返回值：如果指定类的对象可以转换为此类的实例，则此方法返回true 。否则返回false 。

下面的程序演示了 isAssignableFrom() 方法。

示例 1：

// Java program to demonstrate isAssignableFrom() method
  
public class Test {
    public static void main(String[] args)
        throws ClassNotFoundException
    {
  
        // returns the Class object for this class
        Class myClass = Class.forName("Test");
  
        System.out.println("Class represented by myClass: "
                           + myClass.toString());
  
        // get the Class instance using forName() method
        Class c = Class.forName("java.lang.String");
  
        System.out.println("Class represented by c: "
                           + c.toString());
  
        // Check if object c is compatible
        // using isAssignableFrom() method
        System.out.println("Is c compatible: "
                           + myClass.isAssignableFrom(c));
    }
}

输出：

Class represented by myClass: class Test
Class represented by c: class java.lang.String
Is c compatible: false

示例 2：

// Java program to demonstrate isAssignableFrom() method
  
public class Test {
    public static void main(String[] args)
        throws ClassNotFoundException
    {
  
        // returns the Class object for this class
        Class myClass = Class.forName("Test");
  
        System.out.println("Class represented by myClass: "
                           + myClass.toString());
  
        // get the Class instance using forName() method
        Class c = Class.forName("Test");
  
        System.out.println("Class represented by c: "
                           + c.toString());
  
        // Check if object c is compatible
        // using isAssignableFrom() method
        System.out.println("Is c compatible: "
                           + myClass.isAssignableFrom(c));
    }
}

输出：

Class represented by myClass: class Test
Class represented by c: class Test
Is c compatible: true

参考： https://docs.oracle.com/javase/9/docs/api/ Java/lang/Class.html#isAssignableFrom-java.lang.Class-