HashMap 按key排序

1 Object[] key_arr = hashmap.keySet().toArray();   
2 Arrays.sort(key_arr);   
3 for  (Object key : key_arr) {   
4     Object value = hashmap.get(key);   
5 } 

  1 package Aug11.Collection;
  2 
  3 import java.util.*;
  4 
  5 public class EmployeeTest {
  6     static int  EmId=237;
  7     public static void main(String[] args) {
  8         Scanner reader=new Scanner(System.in);
  9         HashMap map = new HashMap();
 10         //TreeMap map = new TreeMap();  //sorted
 11         Employee1 emp;
 12         for (int i = 0; i <3; i++) {
 13             emp=new Employee1();
 14             System.out.println("Enter name:");
 15             String name=reader.next();
 16             System.out.println("Enter address:");
 17             String addr=reader.next();
 18             System.out.println("Enter dateJoined(YY/mm/):");
 19             String dateJoined=reader.next();
 20             System.out.println("Enter dateBirth:");
 21             String dateBirth=reader.next();
 22             System.out.println("Enter basicPay:");
 23             double basicPay=reader.nextDouble();
 24             
 25             emp.setEmpName(name);
 26             emp.setAddr(addr);
 27             emp.setDateJoined(dateJoined);
 28             emp.setBasicPay(basicPay);;
 29             emp.setDateBirth(dateBirth);;
 30             map.put(genEmpID(dateJoined), emp);
 31             
 32         }
 33     
 34         System.out.println("   EmpId     EmpName   Address  DateJoined  DateBirth  BasicPay");
 35          
 36         Object[] key_arr = map.keySet().toArray();     
 37         Arrays.sort(key_arr);     
 38         for  (Object key : key_arr) {     
 39              Employee1 em = (Employee1) map.get(key);    
 40             System.out.println(key+"\t"+em.getEmpName()+"\t"+em.getAddr()+"\t"+em.getDateJoined()+"\t"+em.getDateBirth()+"\t"+em.getBasicPay());
 41 
 42         }  
 43         
 44          /*Set<Integer> set = map.keySet();
 45           Iterator<Integer> iter = set.iterator();
 46          while(iter.hasNext()){
 47               int key = iter.next();
 48               Employee1 em=(Employee1) map.get(key);
 49               System.out.println(key+"\t"+em.getEmpName()+"\t"+em.getAddr()+"\t"+em.getDateJoined()+"\t"+em.getDateBirth()+"\t"+em.getBasicPay());
 50          }*/
 51         
 52          }
 53         
 54     
 55     
 56     
 57     
 58     
 59 public static int genEmpID(String dateJoined){
 60     String EmpID=dateJoined+(EmId+1);
 61     EmId++;
 62     String [] s=EmpID.split("/");
 63     StringBuffer bs=new StringBuffer();
 64     for(int i=0;i<s.length;i++){
 65         bs.append(s[i]);
 66     }
 67     int ID=Integer.parseInt(bs.toString());
 68     return ID;
 69         
 70     }
 71 
 72 }
 73 
 74 
 75 
 76 
 77 
 78 class Employee1 {
 79     private String empName;
 80     private String addr;
 81     private String dateJoined; 
 82     private String dateBirth;
 83     private double basicPay;
 84     
 85     public String getEmpName() {
 86         return empName;
 87     }
 88     public void setEmpName(String empName) {
 89         this.empName = empName;
 90     }
 91     public String getAddr() {
 92         return addr;
 93     }
 94     public void setAddr(String addr) {
 95         this.addr = addr;
 96     }
 97     public String getDateJoined() {
 98         return dateJoined;
 99     }
100     public void setDateJoined(String dateJoined) {
101         this.dateJoined = dateJoined;
102     }
103     public String getDateBirth() {
104         return dateBirth;
105     }
106     public void setDateBirth(String dateBirth) {
107         this.dateBirth = dateBirth;
108     }
109     public double getBasicPay() {
110         return basicPay;
111     }
112     public void setBasicPay(double basicPay) {
113         this.basicPay = basicPay;
114     }
115     
116     
117     
118     
119 }