Java 程式Memory使用量

Java VM內存堆疊的記憶體使用量
現在使用量: Runtime.getRuntime().totalMemory()-Runtime.getRuntime().freeMemory()
由兩次使用量計算出中間使用了多少記憶體

public class MemoryTester {
    public static void main(String[] args) {

        System.out.println("max memory:" 
                + Runtime.getRuntime().maxMemory()
                + " bytes");
        System.out.println("total memory:" 
                + Runtime.getRuntime().totalMemory()
                + " bytes");
        System.out.println("free memory:" 
                + Runtime.getRuntime().freeMemory()
                + " bytes");
        long memory = Runtime.getRuntime().totalMemory()
                - Runtime.getRuntime().freeMemory();

        ArrayList list = new ArrayList();
        for (int i = 0; i < 10000; i++)
            list.add(i);

        System.out.println("max memory:" 
                + Runtime.getRuntime().maxMemory()
                + " bytes");
        System.out.println("total memory:" 
                + Runtime.getRuntime().totalMemory()
                + " bytes");
        System.out.println("free memory:" 
                + Runtime.getRuntime().freeMemory()
                + " bytes");
        memory = Runtime.getRuntime().totalMemory()
                - Runtime.getRuntime().freeMemory() - memory;
        System.out.println(memory + " bytes");
    }
}