Java- Example of Memory management
//Example of Memory management using 3 functions
//totalmemory():: gives total heap size
//freememory()::gives now available heap memory
// gc():: by force calling garbage collector(ie before jvm time slice).
class MemoryDemo
{
public static void main(String ar[])
{
Runtime r=Runtime.getRuntime();
System.out.println("Total Heap Memory="+r.totalMemory());
long mem1;//mem1 store initial free memory
mem1=r.freeMemory();
System.out.println("Initial Free Heap Memory="+mem1);
r.gc();//calling garbage collector by force
mem1=r.freeMemory();
System.out.println(" Free Heap Memory after calling garbage collector="+mem1);
//memory allocation
Integer a[]=new Integer[1000];
for(int i=0;i<1000;i++)
{
a[i]=i;
}
long mem2;// To store free memory after memory allocation
mem2=r.freeMemory();
System.out.println(" Free Heap Memory after memory allocation="+mem2);
System.out.println(" Memory used by 1000 integers ="+(mem1-mem2));
//Memory deallocation
for(int i=0;i<1000;i++)
{
a[i]=null;
}
mem2=r.freeMemory();
System.out.println(" Free Heap Memory after memory deallocation without calling gc="+mem2);
r.gc();
long mem3=r.freeMemory();
System.out.println(" Free Heap Memory after memory deallocation after calling gc="+mem3);
System.out.println(" Memory Released ="+(mem3-mem2));
}
}
