You will need to install a Java Development Kit in order to build MapTool from source. At the time of writing, MapTool 1.5 is built against Java JDK 10. Neither older nor newer Java versions will work. Only 64-bit builds are supported.
- Download the current Java 10 JDK from the Oracle Java Archives page. https://www.oracle.com/technetwork/java/javase/downloads/java-archive-javase10-4425482.html You will need an Oracle account to download.
- Click the "Accept License Agreement" radio button for the JDK.
- Download the Java SE Development Kit. At the time of writing, the current version was 10.0.2. Select the appropriate file for your operating system.
- Install the JDK as appropriate for your operating system.
- Check that running
java -version
from a command line shows Java 10. Also check your command path to verify that the Java 10 JDK is the only one in your path.