Question

I have a requirement like there is an item A that has several sub items like a1,b1,c1… and each sub-item has in turn several sub-items like {a11,a12,a13…} which correspond to a1 and {b11,b12,b13..} which correspond to b1. So, its basically like a tree structure with item A as the root. Now, there is some time-stamp associated with each item and its sub-items. The time-stamp is different for all these items and sub-items. I need to find the item/sub-item with the latest time-stamp. How to proceed to solve this in java. Im kind of new to using data structures.

Answer 1

Use TreeMap

It will suit your need. Here is a sample program from java.samples.com

// Create a tree map 
TreeMap tm = new TreeMap(); 
// Put elements to the map 
tm.put("John Doe", new Double(3434.34)); 
tm.put("Tom Smith", new Double(123.22)); 
tm.put("Jane Baker", new Double(1378.00)); 
tm.put("Todd Hall", new Double(99.22)); 
tm.put("Ralph Smith", new Double(-19.08)); 
// Get a set of the entries 
Set set = tm.entrySet(); 
// Get an iterator 
Iterator i = set.iterator(); 
// Display elements 
while(i.hasNext()) { 
Map.Entry me = (Map.Entry)i.next(); 
System.out.print(me.getKey() + ": "); 
System.out.println(me.getValue()); 
} 
System.out.println(); 
// Deposit 1000 into John Doe's account 
double balance = ((Double)tm.get("John Doe")).doubleValue(); 
tm.put("John Doe", new Double(balance + 1000)); 
System.out.println("John Doe's new balance: " + 
tm.get("John Doe"));