How get haspmap in inserted order?

[shyam sunder prasad]

hi every one,

i am proud to say to be part of code ranch because when i pass question i am getting positive responses.

HashMap hm=new HashMap();

hm.put("id","3");
hm.put("name","shyam");
hm.put("age","26");

if i want to retrieve the values from hashmap ,it may not follow order as i inserted.for that i need to go for

LinkedHashMap

so,in my interview he asked me that as any predefined method is there to retrieve the data from hashmap as we inserted?
please give me solution.

[Rajesh Nagaraju]

There is nothing in a hashMap you can use to get it in the inserted order, however you can use a Tree Map. Tree Map retrieves values in the inserted order

[Jesper de Jong]

Rajesh Nagaraju wrote:Tree Map retrieves values in the inserted order

No, it doesn't. TreeMap sorts the elements by the "natural" order of the keys.

LinkedHashMap will return the elements in the order they were inserted into the map when you iterate over the keySet(), entrySet() or values() of the map.

Map<String, String> map = new LinkedHashMap<String, String>();

map.put("id", "3");
map.put("name", "shyam");
map.put("age", "26");

for (Map.Entry<String, String> entry : map.entrySet()) {
    System.out.println(entry.getKey() + " = " + entry.getValue());
}

This will print the elements in the order they were put into the map:

id = 3
name = shyam
age = 26

[Rajesh Nagaraju]

My apologies, I got it all mixed up

Thanks Jesper

[shyam sunder prasad]

thankyou jasper,

for (Map.Entry<String, String> entry : map.entrySet()) {  
    System.out.println(entry.getKey() + " = " + entry.getValue());  
}

can you explain it.

[Darryl Burke]

The enhanced for statement
The for Statement Tutorial

[shyam sunder prasad]

my condition is you should not use LinkedHashMap ok.

i want method to retrieve in order as i inserted.

[Matthew Brown]

shyam sunder prasad wrote:my condition is you should not use LinkedHashMap ok.

i want method to retrieve in order as i inserted.

Then that's exactly what a LinkedHashMap does, as has been pointed out. Why don't you want to use that?

In a plain HashMap, the information simply doesn't exist any more once they've been added. So your only options would be to extend and modify HashMap (in other words, write your own LinkedHashMap), or keep a separate list of the items you've added so you can control the order of iteration.