類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()方法將此Object強制轉換為該Class或此Class對象表示的接口。

• 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()方法是一個非靜態方法，只能通過類對象訪問，如果嘗試使用類名訪問該方法，則會收到錯誤消息。

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

  cast()方法可能會在投射對象時拋出ClassCastException 。

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

  ClassCastException ：在此異常中，給定對象不為null。

Syntax:

句法：

public Type cast(Object o);

Parameter(s):

參數：

• Object o – represents the object to be cast.

  對象o –表示要投射的對象。

Return value:

返回值：

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

此方法的返回類型為Type ，它根據給定的情況返回以下值：

• It returns the casting object.

  它返回轉換對象。

• It returns null when the given Object is null.

  當給定的Object為null時，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 MainClassMainClass mc = new MainClass();// Display ClassSystem.out.println("mc.getClass():" + mc.getClass());// Creating an instance of class A1 and B1A1 a = new A1();B1 b = new B1();// Casting object b to a by using cast(b) methodObject a1 = A1.class.cast(b);// Display Class of object a , b and a1System.out.println("a.getClass(): " + a.getClass());System.out.println("b.getClass(): " + b.getClass());System.out.println("a1.getClass(): " + a1.getClass());} }

Output

輸出量

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

翻譯自: https://www.includehelp.com/java/class-class-cast-method-with-example.aspx

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