Java 中的类 cast()方法，示例
原文:https://www . geesforgeks . org/class-cast-method-in-Java-with-examples/
java.lang.Class 类 的 cast() 方法用于将指定的对象强制转换为该类的对象。方法在以对象的形式强制转换后返回对象。
语法:
public T[] cast(Object obj)
参数:该方法接受一个参数对象，该对象将被投射
返回值:该方法以对象的形式铸造后返回指定的对象。
异常:如果对象不为空且不可分配给类型 t，则此方法抛出:
- Class exception:
下面的程序演示了 cast()方法。
例 1:
// Java program to demonstrate
// cast() method
import java.util.*;
public class Test {
public static Object obj;
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());
// Cast the object obj to object of myClass
// using cast() method
System.out.println("Object " + obj + " after cast "
+ "upon to class Test: "
+ myClass.cast(obj));
}
}
输出:
Class represented by myClass: class Test
Object null after cast upon to class Test: null
例 2:
// Java program to demonstrate
// cast() method
import java.util.*;
class Main {
private static int obj = 10;
public static void main(String[] args)
throws ClassNotFoundException
{
try {
// returns the Class object for this class
Class myClass = Class.forName("Main");
System.out.println("Class represented by myClass: "
+ myClass.toString());
// Cast the object obj to object of myClass
// using cast() method
System.out.println("Object " + obj + " after cast "
+ "upon to class Test: "
+ myClass.cast(obj));
}
catch (Exception e) {
System.out.println(e);
}
}
}
输出:
Class represented by myClass: class Main
java.lang.ClassCastException: Cannot cast java.lang.Integer to Main
参考:https://docs . Oracle . com/javase/9/docs/API/Java/lang/class . html # cast-Java . lang . object-
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