请热心人帮查下错 说是class Teacher是The public type Teacher must be defined in its own file

请热心人帮查下错 说是class Teacher是The public type Teacher must be defined in its own file
package exe2;


public class exe2 {

/**
* @param args
*/
public static void main(String[] args) {
// TODO Auto-generated method stub
Teacher[] teacher=new Teacher[3];
teacher[0]=new Teacher("001","Jarry","a");
  teacher[1]=new Teacher("002","peter","b");
teacher[2]=new Teacher("003","Tom","c");  
for(int i=0;i<3;i++)
System.out.println(teacher[i].getID()+","+ teacher[i].getName()+","+ teacher[i].getAddress());
teacher[0].setAddress("d");
System.out.println(teacher[0].getID()+","+ teacher[0].getName()+","+ teacher[0].getAddress());
teacher[1].queryTeacher("002");
  teacher[2].queryTeacher("002");
}

}
public class Teacher{
  private String ID;
  private String Name;
  private String Address;
  public Teacher(String id,String name,String address){
  ID=id;
  Name=name;
  Address=address;
  }
  String getID(){
  return this.ID;
  }
  String getName(){
  return this.Name;
  }
  String getAddress(){
  return this.Address;
  }
  void setID(String id){
  ID=id;
  }
  void setName(String name){
  Name=name;
  }
  void setAddress(String address){
  Address=address;
  }
  void queryTeacher(String id){
  if(this.ID==id)
  System.out.println(this.ID);
  else
  System.out.println("erro");
  }  
 }


[解决办法]
将Teacher类放到另一个文件中就行了

建议不要用exe2这样的类名 
类名首字母要大写
[解决办法]
java..