Java产生Class类的三种实例化对象的方法

1.object.getClass

2.类名.class直接根据某个具体的类来取得Class实例化对象

3.Class.forName(String className)

public class TestClass {

public static void main(String[] args) {

//1.object.getClass

Date date1 = new Date();

Class cls = date1.getClass();

//java.util.Date

System.out.println("方法1 " + cls.getName());

//class java.util.Date

System.out.println("方法1 " + cls);

//2.类名.class

//一般用类的全限定名

Class cls1 = java.util.Date.class;

//class java.util.Date

System.out.println("方法2 " + cls1);

//3.推荐用

Class cls2 = null;//放在外面可以访问

try {

cls2 = Class.forName("java.util.Date");

System.out.println("方法3 " + cls2);

} catch (ClassNotFoundException e) {

e.printStackTrace();

}

System.out.println("比较三个对象");

System.out.println(cls1 == cls);

System.out.println(cls == cls2);

}

}

推荐用第三种，第一种已经new了一个对象了，第二种写的太繁琐了

对象实例化的三种方法

1.new关键字

2.反射

3.反序列化

在反射中提供public T newInstance() throws InstantiationException, IllegalAccessException方法

public class TestClass1 {

public static void main(String[] args) throws ClassNotFoundException, IllegalAccessException, InstantiationException {

//1.getClass()方法

Date date = new Date();

Class cls = date.getClass();

try {

Date date1 = (Date) cls.newInstance();

System.out.println("1 " + date1);

} catch (InstantiationException e) {

e.printStackTrace();

} catch (IllegalAccessException e) {

e.printStackTrace();

}

//2.全限定类名.class

Class cls2 = java.util.Date.class;

try {

Date date3 = cls2.newInstance();

System.out.println("2 "+date3);

} catch (InstantiationException e) {

e.printStackTrace();

} catch (IllegalAccessException e) {

e.printStackTrace();

}

Date date3 = cls2.newInstance();

System.out.println("2 "+date3);

//3.Class.forName方法，大写Class

Class cls1 = Class.forName("java.util.Date");

Object date2 = cls1.newInstance();

System.out.println("3 " + date2);

}

}