Java is a popular programming language widely used for software testing. It offers various libraries, frameworks, and tools that make it suitable for testing applications at different levels, including unit testing, integration testing, and functional testing. Here are some ways Java is used in software testing:

1. JUnit: JUnit is a widely used testing framework for writing and running unit tests in Java. It provides annotations like @Test, @Before, @After, etc., which help in organizing and executing tests.

2. TestNG: TestNG is another testing framework that provides more functionality than JUnit. It supports parallel test execution, test configuration, data-driven testing, and more.

3. Selenium: Selenium is a popular open-source automation tool for web application testing. Java can be used with Selenium WebDriver to automate web browsers and perform functional testing of web applications.

4. JMockit and Mockito: These are libraries used for creating mock objects and conducting mock-based testing, especially for testing interactions between classes.

5. Apache JMeter: Java-based tool for load testing and performance testing of web applications. It allows simulating multiple users and measuring the performance of web servers, databases, etc.

6. Cucumber: Cucumber is a behavior-driven development (BDD) tool that allows writing test scenarios in a human-readable format. It can be integrated with Java using the Cucumber-JVM library.

7. Test automation frameworks: Java can be used to develop custom test automation frameworks, which provide a structured approach to writing and organizing automated tests.

8. REST-assured: A Java library for testing RESTful APIs. It provides an expressive syntax for creating HTTP requests and validating responses.

9. JIRA: While not directly for testing, JIRA is a popular issue and project tracking tool that is commonly used to manage and track software testing activities.

Java’s portability, extensive library support, and object-oriented nature make it a versatile choice for software testing. Additionally, many companies prefer Java for testing as they might already have a Java development team, making it easier to integrate testing efforts into their existing development process.