1. package com.imocc.collection;

2. 
   

3. import java.util.Arrays;

4. import java.util.Iterator;

5. import java.util.List;

6. import java.util.ArrayList;

7. 
   

8. public class ListTest {

9.   //用于存放备选课程的List

10.   public java.util.List coursesToSelect;  //cousesToSelect是List数组的名字

11. 
    

12.   public ListTest(){ //主类的构造方法

13.  this.coursesToSelect = new ArrayList();//用于往coursesToSelect中添加备选课程

14.   }

15. 
    

16.     public void testAdd() {

17.  Course cr1 = new Course("1","数据结构"); //还没有创建这个类

18.  coursesToSelect.add(cr1);

19.  Course temp = (Course)coursesToSelect.get(0);

20.  System.out.println("添加了课程"+temp.id+":"+temp.name);

22.  Course cr2 = new Course("2","C语言"); //还没有创建这个类

23.  coursesToSelect.add(0,cr2); //怎么和上面的不一样？是由两个add方法吗？

24.  Course temp2 = (Course)coursesToSelect.get(0);

25.  System.out.println("添加了课程"+temp2.id+":"+temp2.name);

26.  

27.       Course[] course = {new Course("3","离散数学"),new Course("4","汇编语言")};

28.       coursesToSelect.addAll(Arrays.asList(course));

29.       Course temp3 = (Course)coursesToSelect.get(2);

30.       Course temp4 = (Course)coursesToSelect.get(3);     

31.       System.out.println("添加了两门课程："+temp3.id +":"+ temp3.name+

32.      ";"+temp4.id + ":" + temp4.name);

33.       

34.       Course[] course2 = {new Course("5","高等数学"),new Course("6","大学英语")};

35.       coursesToSelect.addAll(2,Arrays.asList(course2));

36.       Course temp5 = (Course)coursesToSelect.get(2);

37.       Course temp6 = (Course)coursesToSelect.get(3);     

38.       System.out.println("添加了两门课程："+temp5.id +":"+ temp5.name+

39.      ";"+temp6.id + ":" + temp6.name);  

40.   

41.     }

42.     

43.     /**

44.      * 取得List中元素的方法

45.      * @param args

46.      */

47. public void testGet(){

48. int size = coursesToSelect.size();

49. System.out.println("有如下课程待选：");

51. for (int i = 0;i < size;i++){

54. Course cr = (Course)coursesToSelect.get(i);

55.    System.out.println("课程:"+ cr.id + ":"+ cr.name);

57. }

58. }

60. /*

61. * 通过迭代器来遍历List

62. */

64. public void testIterator() {

65. Iterator it = coursesToSelect.iterator();

66.      System.out.println("有如下课程待选(通过for each访问)：");

67.      while(it.hasNext()){

68.      Course cr = (Course) it.next();

69.      System.out.println("课程："+cr.id+":"+cr.name);

70.      

71.      

72.      }

73. }

75. //修改List中元素

77. public void testModify(){

78. coursesToSelect.set(4,new Course("7","毛概"));

79. }

80. 
    

81. public static void main(String[] args) {

83. ListTest It = new ListTest();

84.    It.testAdd();  //想添加课程但是在ListTest中没有这个方法！

85.    It.testGet();

86.    It.testIterator();

87.    It.testForEach();

88.    It.testModify();

89.    It.testForEach();

90. }

91. 
    

编译的时候出现以下错误信息：

Exception in thread "main" java.lang.Error: Unresolved compilation problems: 

The method testForEach() is undefined for the type ListTest

The method testForEach() is undefined for the type ListTest

Syntax error, insert "}" to complete ClassBody

1. at com.imocc.collection.ListTest.main(ListTest.java:87)