JAVA_OPTS Environment Variable

JAVA_OPTS is an environment variable used to pass custom settings to Java Virtual Machine. This tutorial demonstrates the use of JAVA_OPTS.

JAVA_OPTS Environment Variable

JAVA_OPTS is a standard environment variable used to set the custom setting for Java Virtual Machine. For example, if we set JAVA_OPTS=-Xmx512m in the tomcat, the startup script will execute org.apache.tomcat.Servert –Xmx512m, the –Xmx is the maximum heap size.

Set JAVA_OPTS Environment Variable

We can set the heap size with JAVA_OPTS using the Set command. Run the following command to set the heap size with JAVA_OPTS.

set JAVA_OPTS="-Xms128m -Xmx1024m"

Where -Xms is the minimum heap size and -Xmx is the maximum heap size.

Run the command prompt as administrator and run the command above. You can also set the heap size according to your requirement.

Get JAVA_OPTS Environment Variable in Java

Once the JAVA_OPTS is set, we can get the settings in Java by using the System.getenv() method. If the JAVA_OPTS is not set, the method will return null.

See example:

package delftstack;

public class Delftstack {
  public static void main(String[] args) {
    String Print = System.getenv("JAVA_OPTS");
    System.out.println(Print);
  }
}

The code above will get the JAVA_OPTS settings. See output:

-Xms128m -Xmx1024m