HURITS Java Developer interview questions

in first round they asked two logical question. an array contains 1,2....100 number but 1 number is missing .find the missing number. find nth number in fibbonaci series using recursion and without recursion. after completing these two logical question they asked mainly on Exception handling. in second round they asked why string object is immutable? what is method overloading and method overriding can u explain with the help of example what is static variable. and three logical question they asked in second round same question as in the first round how to find out missing numberin array. how to find out first non repeating character in string. one pattern (Diamond Shape Pattern Program in Java) then some basic question on jdbc write a simple jdbc programme what is the difference between statement and prepared statement and what is connection pooling? what is synchronization ?some basic question related to core java in the last round (skype) i made some mistake due to my side and i lost the oppertunity and so don't miss the chance.