If you want to know the free memory, and the total memory available in the Java runtime environment then you can use the following code snippet to check.

package org.kodejava.lang;

public class MemoryExample {
    public static void main(String[] args) {
        long freeMemory = Runtime.getRuntime().freeMemory();
        long totalMemory = Runtime.getRuntime().totalMemory();

        System.out.println("Free Memory  = " + freeMemory);
        System.out.println("Total Memory = " + totalMemory);
    }
}

Here is the result of the code snippet above:

Free Memory  = 1018439896
Total Memory = 1029177344