Common Mistake #1: Neglecting Existing Libraries
It’s definitely a mistake for Java Developers to ignore the innumerable amount of libraries written in Java. Before reinventing the wheel, try to search for available libraries - many of them have been polished over the years of their existence and are free to use.
These could be logging libraries, like logback and Log4j, or network related libraries, like Netty or Akka. Some of the libraries, such as Joda-Time, have become a de facto standard.
Common Mistake #2: Missing the ‘break’ Keyword in a Switch-Case Block
These Java issues can be very embarrassing, and sometimes remain undiscovered until run in production. Fallthrough behavior in switch statements is often useful; however, missing a “break” keyword when such behavior is not desired can lead to disastrous results.
If you have forgotten to put a “break” in “case 0” in the code example below, the program will write “Zero” followed by “One”, since the control flow inside here will go through the entire “switch” statement until it reaches a “break”.
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