Apache Groovy and Java Class Library Integration Guide

Apache Groovy and Java Class Library Integration Guide Apache Groovy is a dynamic programming language running on the Java virtual machine (JVM), which can be seamlessly integrated with the Java class library.Groovy provides many convenient grammar and characteristics, making the integration with the Java class library easier and flexible. This article will introduce how to integrate with Groovy and Java libraries, and provide some example code to help you understand and apply these concepts. 1. Import java class library In Groovy, you can directly use the IMPORT statement to import the Java library.If you need to use a specific Java class, use Import keywords to import them on the top of the Groovy script.The following is an example of importing Java.util package to the ArrayList class: import java.util.ArrayList // Or you can use the through -the -paired character to import the entire package import java.util.* 2. Create a Java object In Groovy, you can create a Java object like creating Groovy objects.By using the keyword `new`, you can apply the Java class in Groovy and call its constructor.For example, the following code creates an ArrayList object of Java: def list = new ArrayList() 3. Call the java method You can directly call the Java object method, just like in Java.For example, if you have a Java string object STR, you can obtain its length by calling its `length ()` method: def str = "Hello, World!" def length = str.length() 4. Visit Java field You can directly access the fields of the Java object (member variable).For example, if you have a Java object Person, which contains names and age fields, you can directly access these fields using a point operator: def person = new Person() person.name = "John" person.age = 30 5. Integration of Groovy Closure and Java interface The Groovy closure can be used to implement the Java interface.If you have a Java interface, you can use the Groovy closure to implement it, and then pass it to Java call.The following is an example of implementing the Java Runnable interface: def runnable = { println("Hello from Groovy!") } as Runnable Thread thread = new Thread(runnable) thread.start() In this example, we define a Groovy closure that prints a message when calling.Then, we converted it to the Runnable interface of Java and created a Java thread to execute it. Summarize: The integration of Apache Groovy and Java class libraries is very simple.You can directly import the Java class library, create a Java object, call the Java method and access the Java field, just like in Java.In addition, the Groovy closure can also be used to implement the Java interface for use in the Java code. I hope the example code provided in this article can help you integrate with the Java library in Groovy.Start using Groovy and Java for flexible scalability programming!