String interpolation in Java 14 or 15
There is something slightly closer; an instance version of String::format, called formatted: It is similar to String::format, but is more friendly to use in chained expressions.
Java
How to get an enum value from a string value in Java
Yes, Blah.valueOf(“A”) will give you Blah.A. Note that the name must be an exact match, including case: Blah.valueOf(“a”) and Blah.valueOf(“A “) both throw an IllegalArgumentException. The static methods valueOf() and values() are created at compile time and do not appear in source code. They do appear in Javadoc, though; for example, Dialog.ModalityType shows both methods.
Print ArrayList
list.toString() is good enough. The interface List does not define a contract for toString(), but the AbstractCollection base class provides a useful implementation that ArrayList inherits.
Non-static variable cannot be referenced from a static context
You must understand the difference between a class and an instance of that class. If you see a car on the street, you know immediately that it’s a car even if you can’t see which model or type. This is because you compare what you see with the class “car”. The class contains which is similar to … Read more
What is a StringIndexOutOfBoundsException? How can I fix it?
Error Description Actual Reason Your code trying to create a substring with though your actual response string length is = 28, so String length is not long enough to create a substring of 500 characters. Solutions : Validate length using ternary operator ?:mTextView.setText(“Response is: “+ ((response.length()>499) ? response.substring(0,500) : “length is too short”)); Note : Ternary … Read more
When is the @JsonProperty property used and what is it used for?
Here’s a good example. I use it to rename the variable because the JSON is coming from a .Net environment where properties start with an upper-case letter. This correctly parses to/from the JSON:
Why would a “java.net.ConnectException: Connection timed out” exception occur when URL is up?
I’m getting a ConnectException: Connection timed out with some frequency from my code. The URL I am trying to hit is up. The same code works for some users, but not others. It seems like once one user starts to get this exception they continue to get the exception. Here is the stack trace: Here is a … Read more
Global variables in Java
To define Global Variable you can make use of static Keyword now you can access a and b from anywhere by calling
Java optional parameters
There are several ways to simulate optional parameters in Java: Method overloading.void foo(String a, Integer b) { //… }void foo(String a) { foo(a, 0); // here, 0 is a default value for b }foo(“a”, 2); foo(“a”); One of the limitations of this approach is that it doesn’t work if you have two optional parameters of … Read more
Unsupported major.minor version 52.0 [duplicate]
Pictures: Hello.java Hello.html Error What may the problem be?