To compile and run these programs, you only need JDK 8 installed. Invoking gradlew will automatically download and install Gradle. Gradle will also install all additional libraries necessary to compile and run the Java examples in the book.

To compile everything, the command is:

gradlew build

To run everything (including compiling if necessary), the command is:

gradlew run

To compile only a single chapter (including dependencies), use for example:

gradlew :strings:build

To run only a single chapter, say:

gradlew :strings:run

Gradle can also be used to run a single program. Here, we run the ReplacingStringTokenizer.java program in the strings chapter subdirectory:

gradlew :strings:ReplacingStringTokenizer

However, if the file name is unique throughout the book (the majority are), you can just give the program name, like this:

gradlew ReplacingStringTokenizer

Note that all these commands are run from the base directory where the example code is installed, and where you find the gradlew script.

You can learn about other options by just typing gradlew with no arguments.