I have absolutely no programming experience but need to learn Java – enough to take a J2ME fasttrack course. I only have 10 weeks. Can I do this? What’s your advice about the best resources I can use ?(currently using Sun’s Java Tutorials).
i also had the problem with eclipse and the JRE. Try to delete the 2 Java versions and deinstall eclipse. then install the JDK first and seccond the JRE. after the 2 installations install the new eclipse version(in the installer you chan choose between some installations take the first). i hope I can help you.
clean is its own build lifecycle phase (which can be thought of as an action or task) in Maven. mvn clean install tells Maven to do the clean phase in each module before running the install phase for each module. What this does is clear any compiled files you have, making sure that you’re really compiling each module from scratch.
Java 8 introduces a String.join(separator, list) method; see Vitalii Federenko’s answer. Before Java 8, using a loop to iterate over the ArrayList was the only option: DO NOT use this code, continue reading to the bottom of this answer to see why it is not desirable, and which code should be used instead: In fact, a string concatenation is going … Read more
Your algorithm is fine. However int is too small for your computations, it fails for this input: At some point integer overflows to negative value and your implementation goes crazy, recursing infinitely. Change int num to long num and you’ll be fine – for some time. Later you’ll need BigInteger. Note that according to Wikipedia on Collatz conjecture (bold mine): The longest progression for … Read more
How do I generate a random int value in a specific range? I have tried the following, but those do not work: Attempt 1: Bug: randomNum can be bigger than maximum. Attempt 2: Bug: randomNum can be smaller than minimum.
As the documentation says, this method call returns “a pseudorandom, uniformly distributed int value between 0 (inclusive) and the specified value (exclusive)”. This means that you will get numbers from 0 to 9 in your case. So you’ve done everything correctly by adding one to that number. Generally speaking, if you need to generate numbers from min to max (including both), … Read more
To do this with user input:
Straight from the API Specifications for the ClassCastException: Thrown to indicate that the code has attempted to cast an object to a subclass of which it is not an instance. So, for example, when one tries to cast an Integer to a String, String is not an subclass of Integer, so a ClassCastException will be thrown.
So, you have a com.mysql.jdbc.exceptions.jdbc4.CommunicationsException: Communications link failurejava.net.ConnectException: Connection refused I’m quoting from this answer which also contains a step-by-step MySQL+JDBC tutorial: If you get a SQLException: Connection refused or Connection timed out or a MySQL specific CommunicationsException: Communications link failure, then it means that the DB isn’t reachable at all. This can have one or more of the following causes: IP … Read more