类class cast()方法 (Class class cast() method)

• cast() method is available in java.lang package.

  在java.lang包中提供了cast()方法 。

• cast() method casts this Object to the class or an interface denoted by this Class object.

  cast()方法将此Object强制转换为该Class或此Class对象表示的接口。

• cast() method is a non-static method, it is accessible with the class object only and if we try to access the method with the class name then we will get an error.

  cast()方法是一个非静态方法，只能通过类对象访问，如果尝试使用类名访问该方法，则会收到错误消息。

• cast() method may throw ClassCastException at the time of casting an Object.

  cast()方法可能会在投射对象时抛出ClassCastException 。

  ClassCastException: In this exception when the given object is not null.

  ClassCastException ：在此异常中，给定对象不为null。

Syntax:

句法：

    public Type cast(Object o);

Parameter(s):

参数：

• Object o – represents the object to be cast.

  对象o –表示要投射的对象。

Return value:

返回值：

The return type of this method is Type, it returns the following values based on the given cases,

此方法的返回类型为Type ，它根据给定的情况返回以下值：

• It returns the casting object.

  它返回转换对象。

• It returns null when the given Object is null.

  当给定的Object为null时，它返回null。

Example:

例：

// Java program to demonstrate the example
// of Type cast(Object o) method of Class
class A1 {// A1 Blank implementation
}
class B1 extends A1 {// B1 Blank implementation
}
public class MainClass {public static void main(String[] args) {// Creting an instance of MainClass
MainClass mc = new MainClass();
// Display Class
System.out.println("mc.getClass():" + mc.getClass());
// Creating an instance of class A1 and B1
A1 a = new A1();
B1 b = new B1();
// Casting object b to a by using cast(b) method
Object a1 = A1.class.cast(b);
// Display Class of object a , b and a1
System.out.println("a.getClass(): " + a.getClass());
System.out.println("b.getClass(): " + b.getClass());
System.out.println("a1.getClass(): " + a1.getClass());
}
}

Output

输出量

mc.getClass():class MainClass
a.getClass(): class A1
b.getClass(): class B1
a1.getClass(): class B1

翻译自: https://www.includehelp.com/java/class-class-cast-method-with-example.aspx