Exception in thread “main” java.lang.NumberFormatException: For input string: “S”
The letter S is not a number. Did you mean to write the number 5? Or did you mean to print the ASCII or Unicode value of the character S?
java
How can I clear or empty a StringBuilder?
ways that work: Use stringBuilderObj.setLength(0). Allocate a new one with new StringBuilder() instead of clearing the buffer. Note that for performance-critical code paths, this approach can be significantly slower than the setLength-based approach (since a new object with a new buffer needs to be allocated, the old object becomes eligible for GC etc).
How do I get “Press any key to continue” to work in my Java code?
I want the user to enter information again in the first while loop after pressing any key on the keyboard. How do I achieve that? Am I doing something wrong with the while loops. SHould I just have one while loop?
What is the difference between the HashMap and Map objects in Java?
There is no difference between the objects; you have a HashMap<String, Object> in both cases. There is a difference in the interface you have to the object. In the first case, the interface is HashMap<String, Object>, whereas in the second it’s Map<String, Object>. But the underlying object is the same. The advantage to using Map<String, Object> is that you can change the underlying … Read more
Are arrays passed by value or passed by reference in Java?
Your question is based on a false premise. Arrays are not a primitive type in Java, but they are not objects either … “ In fact, all arrays in Java are objects1. Every Java array type has java.lang.Object as its supertype, and inherits the implementation of all methods in the Object API. … so are they passed by value or by … Read more
Resizing image in Java
If you have an java.awt.Image, rezising it doesn’t require any additional libraries. Just do: Ovbiously, replace newWidth and newHeight with the dimensions of the specified image.Notice the last parameter: it tells to the runtime the algorithm you want to use for resizing. There are algorithms that produce a very precise result, however these take a large time to complete.You can use any of the following … Read more
Can not deserialize instance of java.lang.String out of START_OBJECT token
You’re mapping this JSON that contains an element named data that has a JSON object as its value. You are trying to deserialize the element named workstationUuid from that JSON object into this setter. This won’t work directly because Jackson sees a JSON_OBJECT, not a String. Try creating a class Data the switch up your method
What is the easiest/best/most correct way to iterate through the characters of a string in Java?
I use a for loop to iterate the string and use charAt() to get each character to examine it. Since the String is implemented with an array, the charAt() method is a constant time operation. That’s what I would do. It seems the easiest to me. As far as correctness goes, I don’t believe that exists here. It is … Read more
Exception in thread “main” java.lang.ClassNotFoundException:
The reason you’re getting this error is because you didn’t save the class into a file called Hello.java (case-sensitive!)
what is this ANT build?
I had the exact same problem, where when I clicked “Run” I would get a menu with options of “Ant Build” or “Ant Build…” — even though I had a main method. I finally got my program to run as normal when I copied and pasted my code into a new file in a new … Read more