/*
 * TestMemory.java
 *
 * Created on 30 November 2001, 14:03
 */

package uk.ac.leeds.ccg.andyt.tests;

/**
 *
 * @author  andyt
 * @version 
 */
public class TestMemory {


    /**
    * @param args the command line arguments
    */
    public static void main (String args[]) {

        // Get runtime instance
        Runtime runtime=java.lang.Runtime.getRuntime();

        // Print out total virtual machine memory 
        System.out.println("runtime.totalMemory() "+runtime.totalMemory());
        System.out.println("runtime.totalMemory() is the total amount of memory available:\n"
                          +"This may vary over time, depending on the host environment!");
        System.out.println("runtime.freeMemory() "+runtime.freeMemory());
        System.out.println("runtime.freeMemory() is an approximation of the amount of free memory available:\n"
                          +"The difference between the top of the heap and the runtime.totalMemory()\n"
                          +"(the heap is memory made available for allocating temporary variables.)");

        // Garbage collect and print out total virtual machine memory again
        System.gc();
        System.out.println("runtime.freeMemory() after garbage collecting "+runtime.freeMemory());

        // Set some longs for storing amount of available memory
        long memory1=0;
        long memory2=0;
        long time1=0;
        long time2=0;
        int arraySize=0;
        //arraySize=10000000; OutOfMemoryError
        arraySize=1000000;

        // Estimate how much memory time for a double[arraySize]
        System.gc();
        System.out.println("runtime.freeMemory() "+runtime.freeMemory());
        memory1=runtime.freeMemory();
        time1=System.currentTimeMillis();
        double[] da1=new double[arraySize];
        for (int i=0;i<arraySize;i++) {
            da1[i]=(double)i;
        }
        time2=System.currentTimeMillis();
        System.gc();
        System.out.println("runtime.freeMemory() "+runtime.freeMemory());
        System.out.println("runtime.totalMemory() "+runtime.totalMemory());
        memory2=runtime.freeMemory();
        System.out.println("Time in milliseconds to initialise double["+arraySize+"] "+(time2-time1));
        System.out.println("runtime.freeMemory() difference having initialised double["+arraySize+"] "+(memory1-memory2));

        for (int i=0;i<arraySize;i++) {
            da1[i]=(double)i;
        }

/*
        // How much memory for a int[100]
        memory1=runtime.freeMemory();
        time1=System.currentTimeMillis();
        int[] ia1=new int[arraySize];
        for (int i=0;i<arraySize;i++) {
            ia1[i]=i;
        }
        time2=System.currentTimeMillis();
        memory2=runtime.freeMemory();
        System.out.println("Time to initialise int["+arraySize+"] "+(time2-time1));
        System.out.println("runtime.freeMemory() difference having initialised  for int["+arraySize+"] "+(memory1-memory2));
*/

    }

}