JavaExp: Java and Open Source Technology

The following section summarizes the various Collection Classes as of Java 7 and their important attributes Including HashMap which is not in Collection Framework. HashMap. It provides constant time operation for operations like get and put and remove. Iteration over the Collection values requires time proportional to the capacity of the Map.(values()). Default load factor is .75. HashMap does not maintain the order. HashMap is not synchronized. LinkedHashMap LinkedHashMap orders are maintained It provdes  constant-time performance for operations like get, put and remove. Performace is slightly slower then HashMap due to the overhead of maintaining Linked List. Re-insertion does not effect the insertion order. Iteration over the collection values is proportional to the size of the map    regardless capacity . TreeMap Red-Black tree based implementation. Implement the SortedMap Interface. Map is ascending Key order of the natural order. It has log(n) ...

Java Collections framework, String manipulation etc is something that we often encounter in Development process. For processing collections (like checking null/empty, Intersection, Disjunction) We do have some of the very use full libraries. Some of the Collection related libraries are Apche Commons Collections and Google  Collections(Guava). Problem Use Case This article explains how to convert a Java Map to String(and vice versa) using different libraries and technique. One way is to use StringBuilder(Or String) and loop though the Map and build the String by applying some sort of separator ( for key:value and entry). Here we have to take care of the null value etc. Without Any Library If we want to convert the map to a String with key value separator and also individual entry seperator in the resulting String, we have to write code for that. For a simple Map, we have to iterate though the map, take care of the null values etc. Following is...