Memory.java

public abstract class Memory {

    private static Runtime runtime = Runtime.getRuntime();
    private static int mb = 1024*1024;


    public static long getFree() {
        return runtime.freeMemory() / mb;
    }

    public static long getUsed() {
        return runtime.totalMemory() /  - runtime.freeMemory() / mb;
    }

    public static long getTotal() {
        return runtime.totalMemory() / mb;
    }

    public static long getAvailable() {
        return runtime.maxMemory() / mb;
    }

}