import java.util.*;
/*
每个学生都有对应的归属地
学生student地址String
学生属性:姓名,年龄
注意:姓名和年龄相同的视为同一个学生
保证学生的唯一性
1,描述学生
2,定义map容器,将学生作为键,地址作为值,存入
3,获取map集合中的元素
*/
class Student implements Comparable<Student>
{
private String name;
private int age;
public Student(String name,int age)
{
this.name=name;
this.age=age;
}
public int compareTo(Student s)
{
int num=new Integer(this.age).compareTo(new Integer(s.age));
if(num==0)
return this.name.compareTo(s.name);
return num;
}
public int hashCode()
{
return name.hashCode()+age*34; }
public boolean equals(Object obj)
{
if(! (obj instanceof Student))
throw new ClassCastException("类型不匹配");
Student s=(Student)obj;
return this.name.equals(s.name)&&this.age==s.age;
}
public String getName()
{
return name;
}
public int getAge()
{
return age;
}
public String toString()
{
return name+":"+age;
}
}
class MapTest
{
public static void main(String[] args)
{
HashMap<Student,String> hm=new HashMap<Student,String>();
hm.put(new Student(("lisi1,21"),"beijing"));
hm.put(new Student("lisi2,22"),"Jian");
hm.put(new Student("lisi3,23"),"shenzhen");
hm.put(new Student("lisi4,24"),"guangzhou");
//第一种取出方式 keySet
Set<Student> keySet= hm.keySet();
Iterator<Student> it=keySet.iterator();
while(hasNext())
{
Student stu=it.next();
String addr=hm.get(stu);
System.out.println(stu+".."+addr);
}
}
}
/*
每个学生都有对应的归属地
学生student地址String
学生属性:姓名,年龄
注意:姓名和年龄相同的视为同一个学生
保证学生的唯一性
1,描述学生
2,定义map容器,将学生作为键,地址作为值,存入
3,获取map集合中的元素
*/
class Student implements Comparable<Student>
{
private String name;
private int age;
public Student(String name,int age)
{
this.name=name;
this.age=age;
}
public int compareTo(Student s)
{
int num=new Integer(this.age).compareTo(new Integer(s.age));
if(num==0)
return this.name.compareTo(s.name);
return num;
}
public int hashCode()
{
return name.hashCode()+age*34; }
public boolean equals(Object obj)
{
if(! (obj instanceof Student))
throw new ClassCastException("类型不匹配");
Student s=(Student)obj;
return this.name.equals(s.name)&&this.age==s.age;
}
public String getName()
{
return name;
}
public int getAge()
{
return age;
}
public String toString()
{
return name+":"+age;
}
}
class MapTest
{
public static void main(String[] args)
{
HashMap<Student,String> hm=new HashMap<Student,String>();
hm.put(new Student(("lisi1,21"),"beijing"));
hm.put(new Student("lisi2,22"),"Jian");
hm.put(new Student("lisi3,23"),"shenzhen");
hm.put(new Student("lisi4,24"),"guangzhou");
//第一种取出方式 keySet
Set<Student> keySet= hm.keySet();
Iterator<Student> it=keySet.iterator();
while(hasNext())
{
Student stu=it.next();
String addr=hm.get(stu);
System.out.println(stu+".."+addr);
}
}
}
hm.put(new Student("lisi4,24"),"guangzhou");
^
需要: String,int
找到: String
原因: 实际参数列表和形式参数列表长度不同
hm.put(new Student("lisi4,24"),"guangzhou");
改成
hm.put(new Student("lisi4",24),"guangzhou");
其实就是"这个符号打错了位置。
要学会自己看报错信息调程序
hm.put(new Student("lisi4,24"),"guangzhou");
^
需要: String,int
找到: String也就是你只传递了一个String,而你的int还没有传递
原因: 实际参数列表……楼上的正解,引号范围远了,在IDE下会是红色的吧……