Regex expressions in Java, \\s vs. \\s+?

What's the difference between the following two expressions? x = x.replaceAll("\\s", ""); x = x.replaceAll("\\s+", ...

addKeyListener() doesn't work for JPanel?

I am trying to make a game engine. I have made the Game class but the error resides in the KeyBoard class. Here I le...

Java - Method Invocation & Execution?

What is the difference between the invocation and execution of a method ? Are two the same thing ? ...

Error: org.testng.TestNGException: Cannot find class in classpath: EmpClass?

When i'm trying to run the test suite, am getting this exception. We are using maven project here and i am done with...

“Cannot instantiate the type…”?

When I try to run this code: import java.io.*; import java.util.*; public class TwoColor { public static void ...

Java String import?

I have one doubt. When we use ArrayList or HashMap in Java, we have to import java.util.ArrayList or java.util.HashM...

When to use EntityManager.find() vs EntityManager.getReference() with JPA?

I have come across a situation (which I think is weird but is possibly quite normal) where I use the EntityManager.g...

What is the difference between /* …*/ and /** … */?

I've noticed that Eclipse prints diferent formats to comments: /* Eclipse prints it in green */ or if you write:...

How to parse JSON boolean value??

I have a JSON object JSONObject jsonObject = new JSONObject(); I'm able to populate the object successfully but, ...

Nearby cities or town from my current location?

How to find Nearby cities or town from my current location in android. i can get the nearest places like ATM, hospit...

Shopping Cart Java Application (addToCart)?

I am doing a Java Application for a class and need help with errors that are coming up after running the app. The ...

OpenCV object detection contour position?

I've used openCV library to detect objects of specific colours. The detection of the colour can be changed by playin...