Open Command Prompt or Terminal
Type `java -version`
Press Enter
If Java is installed, version details will appear
If Java is not installed, an error message will appear
Type `javac -version`
Press Enter
If the Java compiler is installed, its version will appear
If `javac` is not recognized, the JDK is not installed or not in PATH
On Windows, type `where java`
On macOS or Linux, type `which java`
If a path is returned, Java is installed
If no path is returned, Java is not installed or not in PATH