HashMap报空指针，求帮助啊！！！

[fengliuqianl]

public static void main(String[] args) {
StudentService studentService = new StudentService();
Student student=null;
for (int i=1; i<=10;i++){
if(i<5){
student = new Student(i,"student"+i,"s100"+i);
}
else{
student = new Student(i,"studnet"+i,"s200"+i);
}
studentService.addStudent(student);//执行到这边的时候报错了。
}

public class StudentService {
public HashMap<String, Student> students = null ;
public void StudnetService(){
students = new HashMap<String, Student>();
}
public void addStudent(Student student) {
if(student==null){
System.out.println("error!!!!!!!!!!");
}else{
System.out.println(student);
}
if(student.getStuName()==null){
System.out.println("error2222!!!!!!!!!!");
}else{
System.out.println(student.getStuName());
}

students.put(student.getStuName(), student);
}


}

定义了一个Student类
public class Student {
private String StuName;
private int stuNo;
private String ClassName;
public Student(int stuNo, String stuName, String ClassName ) {
super();
this.StuName = stuName;
this.stuNo = stuNo;
this.ClassName = ClassName;
}
public String getStuName() {
return StuName;
}
还有有其他参数的get和set就没贴了。
}

调用add方法的时候打印出来的两个参数都不为空啊，
值分别是student [StuName=student1, stuNo=1, ClassName=s1001]和
student1，但是为啥put的时候就出错了呢

[fengliuqianl]

好像有点乱，整理了下，是这样： public class StudentService { public HashMap<String, Student> students = null ; public void StudnetService(){ students = new HashMap<String, Student>(); } public void addStudent(Student student) { if(student==null){ System.out.println("error!!!!!!!!!!"); }else{ System.out.println(student); } if(student.getStuName()==null){ System.out.println("error2222!!!!!!!!!!"); }else{ System.out.println(student.getStuName()); } students.put(student.getStuName(), student); } ////////////////////// public static void main(String[] args) { StudentService studentService = new StudentService(); Student student=null; for (int i=1; i<=10;i++){ if(i<5){ student = new Student(i,"student"+i,"s100"+i); } else{ student = new Student(i,"studnet"+i,"s200"+i); } studentService.addStudent(student);//执行到这边的时候报错了。 } } 另外还有个类

[kemucc]

介个……访问域对不对的……

[kemucc]

StudnetService这个constructer貌似拼错了

[fengliuqianl]

都是在同一个class下啊，除了另外定义的那个类。 “StudnetService这个constructer貌似拼错了”是那个呢？

[kemucc]

引用 4 楼 fengliuqianl 的回复:

都是在同一个class下啊，除了另外定义的那个类。 “StudnetService这个constructer貌似拼错了”是那个呢？

就那个构造函数拼错了……

[菖蒲老先生]

public void StudnetService(){ students = new HashMap<String, Student>(); } 构造函数哪来的void？？？ 改成 public StudentService() {

[soton_dolphin]

构造函数没有返回类型。。。 public void StudnetService(){ 是错的。 应该是public StudentService

[fengliuqianl]

呃，原来是那个StudentService写错了，然后Ctrl+1的时候改成那样了， 谢谢各位大哥大姐啊。