1.write program to sort elements in arraylist 2.difference between arraylist and array? how internally arraylist works 3. how hashmap work internally ? is possible two keys have same hashcode for two key(has collision)?how to avoid it 4.return works in case of exception and finally 5.challenges you face you in development 6.multiple interhence why not allowed in java? is java internally use multiple inheritance? if yes then why it is not allowed outside 7.differnce between wait and sleep ? use of join 8.What use of final variable how to assgn value to final variables 9.what use of static block? how to call it? 10.scenario to use static varible in project ? 11. difference between static,class, and global variables 12.what is properties in collection ? what is difference between properties and hashtable ? 13.changes done in exception handling in JRE 7 14.different way to create object in java