[javastarkid]

Hello,

I am working on creating some Hashmaps in different ways. I am stuck at one place now. I assigned some values to an object and pass that object as value to Hashmap with the key as student. And not knowing how to retrieve those values.

Please Help!

Here is the code I wrote:

StudentHashMap stud=new StudentHashMap();//creating class object
		
		stud.firstName="Santhosh";//Assigning values to object
		stud.lastName="Nellutla";
		stud.rollNumber=1;
		
		HashMap studentMap=new HashMap();// creating HashMap object
		studentMap.put("Student", stud);
		
		stud.studentDetails(studentMap);

[macosxnerd101]

See the HashMap get() method. Also, HashMaps are generic, as are all the other Java Collections.

Why are you creating a custom HashMap here? Or is this just a general Student? If this is just a Student, the class naming conventions are misleading.

StudentHashMap stud=new StudentHashMap();//creating class object 

[g00se]

Assuming Student.rollNumber is unique, you'd need HashMap<Integer, Student>

[javastarkid]

macosxnerd101, on 17 November 2010 - 09:44 AM, said:

See the HashMap get() method. Also, HashMaps are generic, as are all the other Java Collections.

Why are you creating a custom HashMap here? Or is this just a general Student? If this is just a Student, the class naming conventions are misleading.

StudentHashMap stud=new StudentHashMap();//creating class object 

Firstly,Thank you.

Yes I did that too. Here is the code I wrote:

private void studentDetails(HashMap studentMap)// same method I tried to call in the previous code 
	{
		String value = (String)studentMap.get("Student");
		System.out.println(value);
		System.out.println();
		
		/*Set keys = map.keySet();
		Iterator keysIte = keys.iterator();
		
		while(keysIte.hasNext())
		{			
			String key = (String)keysIte.next();
			System.out.println("Book key = "+key+"     And value = "+(String)map.get(key));
		}*/

It is executing without any error but the o/p is :

null