java中arraylist对象排序程序

import java.util.ArrayList;   
import java.util.Collection;   
import java.util.Collections;   
import java.util.Comparator;   
  
  
public class SortTwo implements Comparator {   
//排序字段   
private String sort1;   
//排序方式   
private int state;   
public SortTwo(int state){   
this.state=state;   
}   
public SortTwo(){   
  
}   
public int SortUp(Object o1,Object o2){   
Student stu=(Student) o1;   
Student stu1=(Student) o2;   
if(sort1.equals("name")){   
if(stu.getName().compareTo(stu1.getName())>1){   
return 1;   
} else if(stu.getName().compareTo(stu1.getName())<1){   
return -1;   
}else{   
return 0;   
}   
}   
if(sort1.equals("age")){   
if(stu.getAge().compareTo(stu1.getAge())>1){   
return 1;   
} else if(stu.getAge().compareTo(stu1.getAge())<1){   
return -1;   
}else{   
return 0;   
}   
}   
return 0;   
}   
public int SortDOWN(Object o1,Object o2){   
Student stu=(Student) o1;   
Student stu1=(Student) o2;   
if(sort1.equals("name")){   
if(stu.getName().compareTo(stu1.getName())>1){   
return -1;   
} else if(stu.getName().compareTo(stu1.getName())<1){   
return 1;   
}else{   
return 0;   
}   
}   
if(sort1.equals("age")){   
if(stu.getAge().compareTo(stu1.getAge())>1){   
return -1;   
} else if(stu.getAge().compareTo(stu1.getAge())<1){   
return 1;   
}else{   
return 0;   
}   
}   
return 0;   
}   
public int compare(Object o1, Object o2) {   
  
if(this.state==1){   
return SortUp(o1, o2);   
}else{   
return SortDOWN(o1, o2);   
}   
}   
  
/**  
* @param args  
*/  
public static void main(String[] args) {   
// TODO Auto-generated method stub   
Student stu=new Student();   
stu.setName("123");   
stu.setAge("12");   
Student stu1=new Student();   
stu1.setName("234");   
stu1.setAge("23");   
ArrayList<Student>list=new ArrayList<Student>();   
list.add(stu);   
list.add(stu1);   
SortTwo t=new SortTwo(1);   
t.sort1="age";   
Collections.sort(list,t);   
for(Student st : list){   
System.out.println(st.getName() +"   "+st.getAge());   
}   
}   
  
}