How Do You Assign a Variable in Groovy to Be an Integer Value?

Problem scenario
A Groovy program is returning an incorrect value for an integer variable. What is wrong?

Possible solution #1
Check the logic of your program. Use the println command to see the earliest point when this variable is assigned an incorrect value. This helps you pinpoint the problem.

Possible solution #2
Is the variable being assigned a number in quotes like this?

How Do You Invoke the main Section of a Groovy Program?

Problem scenario
Your Groovy code has a section like this:

class Example {
static void main(String[] args) {

But this section above is not executing when you run your Groovy program. There are no errors however. How do you get it to execute?

Possible Solution #1
Remove lines of code (or statements) that are outside the “class Example {…”

Possible Solution #2
See this posting: How Do You Invoke a Class in a Groovy Program?

How Do You Troubleshoot an Error like This in Groovy “groovy.lang.MissingMethodException”?

Problem scenario
You run a Groovy program like this: groovy foobar.groovy

You see this message:

Caught: groovy.lang.MissingMethodException: No signature of method: java.lang.Boolean.call() is applicable for argument types: (foobar$_run_closure5$_closure6) values: [foobar$_run_closure5$_closure6@6150c3ec]
Possible solutions: wait(), any(), wait(long), and(java.lang.Boolean), each(groovy.lang.Closure), any(groovy.lang.Closure)
groovy.lang.MissingMethodException: No signature of method: java.lang.Boolean.call() is applicable for argument types: (foobar$_run_closure5$_closure6) values: [foobar$_run_closure5$_closure6@6150c3ec]
Possible solutions: wait(), any(), wait(long), and(java.lang.Boolean), each(groovy.lang.Closure), any(groovy.lang.Closure)
at foobar$_run_closure5.doCall(foobar.groovy:56)

What should you do?

How Write a Custom Method inside of a Class in Groovy?

Problem scenario
You are familiar with Groovy scripts. Now you want to use a class and a method in the class. How do you do this?

Solution
Prerequisites
Install Groovy. See these directions for Ubuntu/Debian if you need assistance; see these directions for CentOS.

Procedures

  1. Create a file called test.groovy with the content below:

class Example {
def static Display(nifty) {
nifty.call(“Red”); …

How Do You Troubleshoot the Groovy Error “JAVA_HOME is not defined correctly”?

One of the following situations apply to you:

Problem scenario #1
You try to run a Groovy command (e.g., groovy foobar.groovy), but you get this error:
“groovy: JAVA_HOME is not defined correctly, can not execute: /usr/lib/jvm/java-9-openjdk/bin/java”

Problem scenario #2
You get this error when you run an “hdfs” command:

ERROR: /usr/bin//bin/java is not executable.

What should you do?

What is a Multi-branch Jenkins Job?

Question
With a newer version of Jenkins, you want to know what a multi-branch job is. What is a multi-branch Jenkins job?

Answer
In Jenkins, a project is a job; the term job has been deprecated however (according to the Jenkins’ website). To see the difference between a Jenkins pipeline and a Jenkins project, see this posting: What Is the Difference between a Jenkins Project and a Jenkins Pipeline?

How Do You Write a Tic-Tac-Toe Program in Groovy?

Problem scenario
You want to code a Groovy 2.x program.  You want a program that reads user input, prints out processed output, uses closures (similar to functions in other languages) with and without return statements, handles some exceptions (non-standard input or input that is no longer valid based on what was previously entered), and uses classes.  How do you write a Tic-Tac-Toe (aka naughts and crosses) program in Groovy that has the above things?

How Do You Invoke a class in a Groovy Program?

Problem scenario
You have a Groovy with these lines of code:

class Contint {
   static void main(String[] args) {
      def apple = {println “This is a basic test.”};
      apple.call();
   }
}
println “This is the second print statement in the code.”

The “Contint” class is never invoked.  What should you do?

Solution
Overview

You need to use the “new” reserved word.  This will instantiate the class.