求助！！！

伍碧林 · 伍碧林

本帖最后由伍碧林于 2011-10-11 23:08 编辑

刘一锋发表于 2011-10-11 21:33
伍碧林犀利啊，我就是这个意思，一开始我写的时候已经写了public boolean putEmployee(String name, Obje ...

赫赫.过奖啦.我也是新手呢.说到了HashMap的迭代,我去看文档,然后小小的总结了下.自己复习了.希望也可以帮到你哈...
HashMap集合下的public Set<Map,Entry<K,V>> entrySet(); HashMap->Set(方式一)
或者
HashMap集合下的public Set<K> keySet() ;Hash->Set (方式二)
Set集合下的public Iterator<E> iterator()方法; Set->iterator
Iterator接口下public boolean hasNext() ,public E next(),public void remove() ;可以迭代输出了,方式一效率比方式二效率高

wangfayin

为什么输出时null呢？

import java.util.*;
class Employee
{ private String name;
private char sex;
private int birthday;
private String degree;
private String title;
private String address;
private String telephone;
public Employee( char sex, int birthday, String degree, String title, String telephone)
{
this.sex =sex;
this.birthday =birthday;
this.degree =degree;
this.title =title;
this.title =title;
this.telephone=telephone;
}
public Employee(String name)
{
this.name =name;
}
public void setName(String name)
{ this.name =name; }
public void setSex(char sex)
{ this.sex =sex; }
public void setBirthday(int birthday)
{this.birthday =birthday; }
public void setDegree(String degree)
{ this.degree =degree;}
public void setTitle(String title)
{ this.title =title;}
public void setAddress(String address, String title)
{ this.title =title;}
public void setTelephone(String telephone)
{ this.telephone=telephone;}
public String getName()
{
return name;
}
public char getSex()
{
return sex;
}
public int getBirthday()
{
return birthday;
}
public String getDegree()
{
return degree;
}
public String getTitle()
{
return title;
}
public String getAddress()
{
return address;
}
public String getTelephone()
{
return telephone;
}
}
class EmployManager
{
private static HashMap<String, Object> EmployeeListHT = new HashMap<String, Object>();
//public Object getName(Object obj)
//{
// obj= get(obj);
// return obj;
//
public boolean putEmployee(String name ,Object obj)
{
EmployeeListHT.put( name,obj);
return true;
}
public void putEmployee(Employee employee, Employee employee2) {
// TODO Auto-generated method stub
}
public void putEmployee(Object object, Object object2) {
// TODO Auto-generated method stub
}
public static Employee getEmployee(String name )
{
return(Employee) EmployeeListHT.get(name) ;
}
}
/* public static boolean removeEmployee(String name)
{
EmployeeListHT.remove(name);
return true;
}*/
class CommandStage extends EmployManager
{
//public static void sop(Object obj)
//{System.out.println(obj);}
@SuppressWarnings("unchecked")
public static void main(String[] srgs)
{
EmployManager em = new EmployManager();
em.putEmployee((Object)new Employee("刘一锋") ,(Object)new Employee('1',22,"22","2","22"));
System.out.println(getEmployee("刘一锋"));
//sop(toString());
/* Set<Employee> keySet = (Set<Employee>) em.keySet();
Iterator<Employee> it = keySet.iterator();
while(it.hasNext())
{
Employee emp =(Employee) it.next();
}*/
}
}

复制代码

林国锋 · 林国锋

请看你代码的105行, em.putEmployee((Object)new Employee("刘一锋") ,(Object)new Employee('1',22,"22","2","22"));这个方法什么都没有实现肯定是空的,这集合怎么写得有点乱?具体像要实现什么功能?是要在hashmap中存对象吗?

赵玉成 · 赵玉成

你的 HashMap EmployeeListHT里没有加入任何值，在EmployManager 类中加一方法：
public static HashMap<String, Object> getmap()
{

return EmployeeListHT;
}

然后在main方法中System.out.println(em.getmap());
打印EmployeeListHT值为空{}

刘一锋 · 刘一锋

愁思我了，eclipse帮助的时候加了一些我看不懂的东西

刘一锋 · 刘一锋

import java.util.*;
class Employee
{ private String name;
private char sex;
private int birthday;
private String degree;
private String title;
private String address;
private String telephone;
public Employee( char sex, int birthday, String degree, String title, String telephone)
{
this.sex =sex;
this.birthday =birthday;
this.degree =degree;
this.title =title;
this.title =title;
this.telephone=telephone;
}
public Employee(String name)
{
this.name =name;
}
public void setName(String name)
{ this.name =name; }
public void setSex(char sex)
{ this.sex =sex; }
public void setBirthday(int birthday)
{this.birthday =birthday; }
public void setDegree(String degree)
{ this.degree =degree;}
public void setTitle(String title)
{ this.title =title;}
public void setAddress(String address, String title)
{ this.title =title;}
public void setTelephone(String telephone)
{ this.telephone=telephone;}
public String getName()
{
return name;
}
public char getSex()
{
return sex;
}
public int getBirthday()
{
return birthday;
}
public String getDegree()
{
return degree;
}
public String getTitle()
{
return title;
}
public String getAddress()
{
return address;
}
public String getTelephone()
{
return telephone;
}
}
class EmployManager
{
private static HashMap<String, Object> EmployeeListHT = new HashMap<String, Object>();
public boolean putEmployee(String name ,Object obj)
{
EmployeeListHT.put( name, obj);
return true;
}
public static Employee getEmployee(String name )
{
return(Employee) EmployeeListHT.get(name) ;
}
public void putEmployee(Employee employee, Object object) {
// TODO Auto-generated method stub
}
}
/* public static boolean removeEmployee(String name)
{
EmployeeListHT.remove(name);
return true;
}*/
class CommandStage extends EmployManager
{
@SuppressWarnings("unchecked")
public static void main(String[] srgs)
{
EmployManager em = new EmployManager();
em.putEmployee((Employee)new Employee("刘一锋") ,(Object)new Employee('1',22,"22","2","22"));
System.out.println(getEmployee("刘一锋"));
}
}

复制代码

这样能看到过了吗？大家

刘一锋 · 刘一锋

import java.util.*;
class Employee
{ private String name;
private char sex;
private int birthday;
private String degree;
private String title;
private String address;
private String telephone;
public Employee( char sex, int birthday, String degree, String title, String telephone)
{
this.sex =sex;
this.birthday =birthday;
this.degree =degree;
this.title =title;
this.title =title;
this.telephone=telephone;
}
public Employee(String name)
{
this.name =name;
}
public void setName(String name)
{ this.name =name; }
public void setSex(char sex)
{ this.sex =sex; }
public void setBirthday(int birthday)
{this.birthday =birthday; }
public void setDegree(String degree)
{ this.degree =degree;}
public void setTitle(String title)
{ this.title =title;}
public void setAddress(String address, String title)
{ this.title =title;}
public void setTelephone(String telephone)
{ this.telephone=telephone;}
public String getName()
{
return name;
}
public char getSex()
{
return sex;
}
public int getBirthday()
{
return birthday;
}
public String getDegree()
{
return degree;
}
public String getTitle()
{
return title;
}
public String getAddress()
{
return address;
}
public String getTelephone()
{
return telephone;
}
}
class EmployManager
{
private static HashMap<String, Object> EmployeeListHT = new HashMap<String, Object>();
public boolean putEmployee(String name ,Object obj)
{
EmployeeListHT.put( name, obj);
return true;
}
public static Employee getEmployee(String name )
{
return(Employee) EmployeeListHT.get(name) ;
}
public void putEmployee(Employee employee, Object object) {
// TODO Auto-generated method stub
}
}
/* public static boolean removeEmployee(String name)
{
EmployeeListHT.remove(name);
return true;
}*/
class CommandStage extends EmployManager
{
@SuppressWarnings("unchecked")
public static void main(String[] srgs)
{
EmployManager em = new EmployManager();
em.putEmployee((Employee)new Employee("刘一锋") ,(Object)new Employee('1',22,"22","2","22"));
System.out.println(getEmployee("刘一锋"));
}
}

复制代码

这样能看到过了吗？大家

刘一锋 · 刘一锋

em.putEmployee((Employee)new Employee("刘一锋") ,(Object)new Employee('1',22,"22","2","22"));

这句话怎么就没存进数据呢？

伍碧林 · 伍碧林

本帖最后由伍碧林于 2011-10-11 20:39 编辑

啊,这么多回复了啊...我没有去打球还是给你看了下,自己辛苦了下,还是把代码贴进来.修改的地方,注释中写了....{:soso_e100:}
结果:
刘一锋
性别:男生日:22 学位 :22 标题:2 地址:100 电话:22(乱写的数据)

import java.util.*;
class Employee {
private String name;
private char sex;
private int birthday;
private String degree;
private String title;
private String address;
private String telephone;
public Employee(char sex, int birthday, String degree, String title,String address,//改了
String telephone) {
this.sex = sex;
this.birthday = birthday;
this.degree = degree;
this.title = title;
this.address = address;
this.telephone = telephone;
}
public Employee(String name)
{
this.name = name;
}
public void setName(String name)
{
this.name = name;
}
public void setSex(char sex)
{
this.sex = sex;
}
public void setBirthday(int birthday) {
this.birthday = birthday;
}
public void setDegree(String degree)
{
this.degree = degree;
}
public void setTitle(String title)
{
this.title = title;
}
public void setAddress(String address, String title)
{
this.title = title;
}
public void setTelephone(String telephone)
{
this.telephone = telephone;
}
public String getName()
{
return name;
}
public char getSex()
{
return sex;
}
public int getBirthday()
{
return birthday;
}
public String getDegree()
{
return degree;
}
public String getTitle()
{
return title;
}
public String getAddress()
{
return address;
}
public String getTelephone()
{
return telephone;
}
//添加了
public String toString(){
return "性别:"+this.sex+" 生日:"+this.birthday+" 学位 :"+this.degree
+" 标题:"+this.title+" 地址:"+this.address+ " 电话:"+this.telephone;
}
}
class EmployManager
{
private static HashMap<String, Object> EmployeeListHT = new HashMap<String, Object>();
// public Object getName(Object obj)
// {
// obj= get(obj);
// return obj;
//
public boolean putEmployee(String name, Object obj)//
{
EmployeeListHT.put(name, obj);
return true;
}
public void putEmployee(Employee employee, Employee employee2) {
// TODO Auto-generated method stub
}
public void putEmployee(Object object, Object object2) {
// TODO Auto-generated method stub
}
public static Employee getEmployee(String name)
{
return (Employee) EmployeeListHT.get(name);
}
//自动生成的代码
//EmployeeListHT这个属性的get()和set()方法,因为后面用到了em.getEmployeeListHT(),因为你的EmployeeListHT 是private的,需要get()和set(),也只有它才是真正存数据的HashMap.
public void setEmployeeListHT(HashMap<String, Object> employeeListHT) {
EmployeeListHT = employeeListHT;
}
public HashMap<String, Object> getEmployeeListHT() {
return EmployeeListHT;
}
}
/*
* public static boolean removeEmployee(String name)
*
* {
*
* EmployeeListHT.remove(name);
*
* return true;
*
* }
*/
public class temp extends EmployManager
{
// public static void sop(Object obj)
// {System.out.println(obj);}
@SuppressWarnings("unchecked")
public static void main(String[] srgs)
{
EmployManager em = new EmployManager();
// em.putEmployee((Object) new Employee("刘一锋"), (Object) new Employee('1',
// 22, "22", "2", "22"));
//这里改了.根据你的意思.是通过"刘一锋"找他的信息
//你用的putEmployee(Object object ,Object object2)这个方法,但是你方法体为空.所以就给你改成了
//public boolean putEmployee(String name, Object obj)因为你有方法体
em.putEmployee(new String("刘一锋"), (Employee) new Employee('男',
22, "22", "2","100", "22"));
//你后面代码大概是这个意思...
Set<Map.Entry<String, Object>> itor =em.getEmployeeListHT().entrySet();
Iterator<Map.Entry<String, Object>> iter=itor.iterator();
while(iter.hasNext()){
Map.Entry<String, Object> me = iter.next();
System.out.println(me.getKey());
System.out.println(me.getValue());
}
// sop(toString());
}
}

复制代码

伍碧林 · 伍碧林

本帖最后由伍碧林于 2011-10-11 20:35 编辑

刘一锋发表于 2011-10-11 20:08
em.putEmployee((Employee)new Employee("刘一锋") ,(Object)new Employee('1',22,"22","2","22"));

根据你的参数你调用的是
public void putEmployee(Employee employee, Object object)
   {
            // TODO Auto-generated method stub
   }
这个方法,但是你方法体是空的啊.:)
你的只有下面这个方法有hashMap的put方法,只有这个方法才可以往hashMap里面加<key,value>啊
才不会空啊
public  boolean putEmployee(String name ,Object obj)
      {
            EmployeeListHT.put( name, obj);
            return true;
      }

刘一锋 · 刘一锋

我感觉楼上是神，等我仔细看一下

刘一锋 · 刘一锋

伍碧林犀利啊，我就是这个意思，一开始我写的时候已经写了public boolean  putEmployee(String name, Object obj)//

      {

            EmployeeListHT.put(name, obj);

            return true;

是有方法体的，但是可能是我类型转换那块弄得不好，在用软件瞎调试的时候，不知道他为啥给我加了个没方法体的函数，我还没看出来，楼上的代码改的我差不多都能懂，就是迭代那块有模糊，我在研究一下，呵呵，谢谢你了，我要是管理肯定给你加分啊，真的感谢！

刘一锋 · 刘一锋

这两种方式是不是可以记下来，到时候往里套就ok了，一会我也复习一下，看的太快不扎实啊！共勉！

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