Java, Simplified check if int array contains int
Here is Java 8 solution
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Class is not Abstract and does not Override error in Java
How to reproduce that error as simply as possible: Java code: Shows this compile time error: Why won’t it compile? Because: You created a class Cat which implements an interface Animal. Your interface called Animal has an abstract method called roar which must be overridden. You didn’t provide for method roar. There are many ways … Read more
java constructor in class cannot be applied to given types
Since your super class Person doesn’t have a default constructor, in your sub classes (Student and Staff), you must call the super class constructor as the first statement. You should define your sub class constructors like this:
Syntax error on token(s), misplaced construct(s)
You need to place all statements after the declarations in a code block, e.g. method rather than the class block. Logically it probably makes sense to place all statements in the code block but the non-declarative statements need to be enclosed within the new block
Empty an array in Java / processing
There’s Not that it does anything different than you’d do on your own (it just loops through every element and sets it to null). It’s not native in that it’s pure Java code that performs this, but it is a library function if maybe that’s what you meant. This of course doesn’t allow you to resize the array (to … Read more
No appenders could be found for logger(log4j)?
This Short introduction to log4j guide is a little bit old but still valid. That guide will give you some information about how to use loggers and appenders. Just to get you going you have two simple approaches you can take. First one is to just add this line to your main method: Second approach is to … Read more
keytool error bash: keytool: command not found
These are the steps which solved my problem: Search the path where my java was installed find / -name jre Move to java directory (where jre was installed on my server) cd /path/to/jre/bin Create SSL certificate with keytool command ./keytool -genkey -alias [mypassword] -keyalg [RSA]
Getting warning “NDK is missing a ‘platforms” directory.’ with no NDK
Please refer to these two links: How to fix android studios 2.3 NDK bug? https://github.com/requery/requery/issues/467 This is caused by upgrading to Android gradle plugin 2.3 (com.android.tools.build:gradle:2.3.0). In previous versions of the plugin the databinding package name (where the BR file is generated) was provided on an annotation in a generate file. In the new version … Read more
How do I make the method return type generic?
You could define callFriend this way: Then call it as such: This code has the benefit of not generating any compiler warnings. Of course this is really just an updated version of casting from the pre-generic days and doesn’t add any additional safety.
How to add an object to an ArrayList in Java
You need to use the new operator when creating the object or else and your constructor shouldn’t contain void. Else it becomes a method in your class.