Java类class cast（）方法及示例

偏执的太偏执、 2023-03-05 15:52 29阅读 0赞

## 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][https_www.includehelp.com_java_class-class-cast-method-with-example.aspx]

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