Add Strings in HashMap

[renu richard]

Hi,

I want to create a HashMap which is having the key as 1,2,3..... and the value as strings. When i try adding it, i could find only the put method whioch takes only the objects as the input. Can anyone please tell me hiow can i add these strings and integer values into the hashmap table. Thanks.

[Pawel Nowacki]

You mean this put? :
http://java.sun.com/j2se/1.4.2/docs/api/java/util/HashMap.html#put(java.lang.Object,%20java.lang.Object)

You can put here Integer and String. You can't put explicit primitives there.

[renu richard]

Yes. This put method only.

Error i am getting is "No match was found for the method put(int, java.lang.String) in type java.util.HashMap

[Pawel Nowacki]

You can't put int in there as it expects Object. So i guess you should wrap your int in Integer...

[Balagopal Kannampallil]

Hi Renu,

With Java 1.5 came autoboxing and generics. You can do it in two ways.
Using generics

Map myMap = new HashMap<Integer, String>();
//Generics is used here, we ask the compiler to accept Integer as key and String as value in Map myMap
myMap.put(1,"Apple");
//1 is autoboxed and taken as object of type Integer. We don't have to worry about anything else.
myMap.put(2,"Orange");
System.out.println(myMap.get(1));
//Here also autoboxing comes into play. It prints Apple

You can use this without generics also. Like this

Map myMap = new HashMap();
myMap.put(1,"Apple"); //autoboxing
myMap.put(2,"Orange");
System.out.println(myMap.get(1)); //autoboxing. It prints Apple

If you are still sticking on to 1.4, you can write it like this

Map myMap = new HashMap();
myMap.put(new Integer(1),"Apple");
myMap.put(new Integer(1),"Orange");
System.out.println(myMap.get(new Integer(1)));

[edit]Add newlines to keep all text within screen width. CR[/edit]

[renu richard]

Hi Bala,
Its Working.
I have added something like this.

mp.put(this.tempdate,new Integer(this.arrayLength));

Now i want to get the value of arraylength when i give the tempdate value.

mp.get(this.tempdate)

I want to know how to which variable i can assign this to.Can i do something like

int i = mp.get(this.tempdate)

Thanks

[Campbell Ritchie]

 

renu richard wrote: . . . I want to know how to which variable i can assign this to.Can i do something like

int i = mp.get(this.tempdate)

Yes, as long as the compiler knows you are returning an Integer. It will work in Java5 if you declare the Map as Map<Something, Integer> and instantiate it with the types too. In Java1.4 and older, you would have to use a class cast and some method of the Integer class to get the value.