What is the purpose of using try, catch blocks?-Collection of common programming errors

No, it is not a replacement for an if, then block, it serves an entirely different purpose. The objective of a try, catch block is to try and do something which could fail and raise an exception (e.g., read a file from disk, but the file might not be there, etc.). After catching an exception, you can handle it.

try {
   riskyOperation();
catch (ExpectedException) {
   handleException();
}