What is wrong with the code there are lots of error while debugging. I am writing a code for a singleton class to connect with the database mysql. Here is my code I am new to java. Please help.
Casting in Java isn’t magic, it’s you telling the compiler that an Object of type A is actually of more specific type B, and thus gaining access to all the methods on B that you wouldn’t have had otherwise. You’re not performing any kind of magic or conversion when performing casting, you’re essentially telling the … Read more
but as for this method, I don’t understand the purpose of Integer.MAX_VALUE and Integer.MIN_VALUE. By starting out with smallest set to Integer.MAX_VALUE and largest set to Integer.MIN_VALUE, they don’t have to worry later about the special case where smallest and largest don’t have a value yet. If the data I’m looking through has a 10 … Read more
I have a string like I would like to print it this way Can anybody help me?
Most of the times this is a bug in the VM. But it can be caused by any native code (e.g. JNI calls). The hs_err_pidXXX.log file should contain some information about where the problem happened. You can also check the “Heap” section inside the file. Many of the VM bugs are caused by the garbage … Read more
If you want to pause then use java.util.concurrent.TimeUnit: To sleep for one second or To sleep for a minute. As this is a loop, this presents an inherent problem – drift. Every time you run code and then sleep you will be drifting a little bit from running, say, every second. If this is an issue … Read more
I think it’s a historical thing – if a package is introduced as an addition to an existing JRE, it comes in as javax. If it’s first introduced as part of a JRE (like NIO was, I believe) then it comes in as java. Not sure why the new date and time API will end up as javax following this logic … Read more
Since Java 5 you can use Arrays.toString(arr) or Arrays.deepToString(arr) for arrays within arrays. Note that the Object[] version calls .toString() on each object in the array. The output is even decorated in the exact way you’re asking. Examples: Simple Array:String[] array = new String[] {“John”, “Mary”, “Bob”}; System.out.println(Arrays.toString(array)); Output:[John, Mary, Bob] Nested Array:String[][] deepArray = new String[][] {{“John”, “Mary”}, {“Alice”, “Bob”}}; System.out.println(Arrays.toString(deepArray)); //output: … Read more
The type char is a primitive — not an object — so it cannot be dereferenced Dereferencing is the process of accessing the value referred to by a reference. Since a char is already a value (not a reference), it can not be dereferenced. use Character class:
First, it’s kind of weird, to see you run java -jar “app” and not java -jar app.jar Second, to make a jar executable… you need to jar a file called META-INF/MANIFEST.MF the file itself should have (at least) this one liner: Where com.mypackage.MyClass is the class holding the public static void main(String[] args) entry point. Note that there are several ways to … Read more