1、Java api
public T cast(Object obj);
Casts an object to the class or interface represented 解释的比较笼统，意思就是将一个对象装换为类或者接口。
2、代码示例
/**
* Created by shengke on 2016/10/22.
*/
class A {
public static void show() {
System.out.println("Class A show() function");
}
} class B extends A {
public static void show() {
System.out.println("Class B show() function");
}
} public class TestCast { public static void main(String[] args) { TestCast cls = new TestCast();
Class c = cls.getClass();
System.out.println(c); Object obj = new A();
B b1 = new B();
b1.show(); // casts object
A a = new A();
a = A.class.cast(b1); System.out.println(obj.getClass());
System.out.println(b1.getClass());
System.out.println(a.getClass());
}
}
执行结果
class com.scot.effective.genericity.TestCast
Class B show() function
class com.scot.effective.genericity.A
class com.scot.effective.genericity.B
class com.scot.effective.genericity.B
核心为：a = A.class.cast(b1); 把a转化为了B类型，此处容易产生把b1转成A类型误解。
3、源码
/**
* Casts an object to the class or interface represented
* by this {@code Class} object.
*
* @param obj the object to be cast
* @return the object after casting, or null if obj is null
*
* @throws ClassCastException if the object is not
* null and is not assignable to the type T.
*
* @since 1.5
*/
public T cast(Object obj) {
if (obj != null && !isInstance(obj))
throw new ClassCastException(cannotCastMsg(obj));
return (T) obj;
}
4、总结
此方法只能转换当前类型或其子类下的对象，只是简单进行强转。