ArrayList 对象排序实例

1. import java.util.ArrayList;   
2. import java.util.Collection;   
3. import java.util.Collections;   
4. import java.util.Comparator;   
5.   
6.   
7. public class SortTwo implements Comparator {   
8. //排序字段   
9. private String sort1;   
10. //排序方式   
11. private int state;   
12. public SortTwo(int state){   
13. this.state=state;   
14. }   
15. public SortTwo(){   
16.   
17. }   
18. public int SortUp(Object o1,Object o2){   
19. Student stu=(Student) o1;   
20. Student stu1=(Student) o2;   
21. if(sort1.equals("name")){   
22. if(stu.getName().compareTo(stu1.getName())>1){   
23. return 1;   
24. } else if(stu.getName().compareTo(stu1.getName())<1){   
25. return -1;   
26. }else{   
27. return 0;   
28. }   
29. }   
30. if(sort1.equals("age")){   
31. if(stu.getAge().compareTo(stu1.getAge())>1){   
32. return 1;   
33. } else if(stu.getAge().compareTo(stu1.getAge())<1){   
34. return -1;   
35. }else{   
36. return 0;   
37. }   
38. }   
39. return 0;   
40. }   
41. public int SortDOWN(Object o1,Object o2){   
42. Student stu=(Student) o1;   
43. Student stu1=(Student) o2;   
44. if(sort1.equals("name")){   
45. if(stu.getName().compareTo(stu1.getName())>1){   
46. return -1;   
47. } else if(stu.getName().compareTo(stu1.getName())<1){   
48. return 1;   
49. }else{   
50. return 0;   
51. }   
52. }   
53. if(sort1.equals("age")){   
54. if(stu.getAge().compareTo(stu1.getAge())>1){   
55. return -1;   
56. } else if(stu.getAge().compareTo(stu1.getAge())<1){   
57. return 1;   
58. }else{   
59. return 0;   
60. }   
61. }   
62. return 0;   
63. }   
64. public int compare(Object o1, Object o2) {   
65.   
66. if(this.state==1){   
67. return SortUp(o1, o2);   
68. }else{   
69. return SortDOWN(o1, o2);   
70. }   
71. }   
72.   
73. /**  
74. * @param args  
75. */  
76. public static void main(String[] args) {   
77. // TODO Auto-generated method stub   
78. Student stu=new Student();   
79. stu.setName("123");   
80. stu.setAge("12");   
81. Student stu1=new Student();   
82. stu1.setName("234");   
83. stu1.setAge("23");   
84. ArrayList<Student>list=new ArrayList<Student>();   
85. list.add(stu);   
86. list.add(stu1);   
87. SortTwo t=new SortTwo(1);   
88. t.sort1="age";   
89. Collections.sort(list,t);   
90. for(Student st : list){   
91. System.out.println(st.getName() +"   "+st.getAge());   
92. }   
93. }   
94.   
95. }