谁知道答案是多少？为什么？
package de;

public class TestStudent {
   
     public static void main(String args[]) {
             TestStudent ts = new TestStudent();
            Student student = new Student();  
            student.setId(1);  
            student.setName("elong");  
            student.setClassId(1);  
            
            ts.change(student);  
            System.out.println(student);  
        }  
        public void change(Student student){  
            Student student2 = new Student();  
            student2.setId(2);  
            student2.setName("elongdeo");  
            student2.setClassId(2);  
         
            student.setId(3);  
            student.setName("dingyinlong");  
            student.setClassId(3);  
           
            student = student2;   
        
            student.setId(4);  
            student.setName("yinlong");  
            student.setClassId(4);  
        }  

}

答案显示输出的是