A Java OutofMemoryError occurs if infinite the program attempts to use more heap space is assumedthan is available, even after garbage collection. This error can result from:
- A memory leak
- An infinite loop
- The program requires more memory than what is available by default on the heap
- Incorrect implementation of common data structures (hash tables, vectors and so on)
- Unbound deserialization
- Upon writing a large number of objects to an
ObjectOutputStream
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public class ShowHeapError {
/* Assuming the heap size as 512 MB (calculated as 1/4th of 2 GB RAM = 512 MB)
* Considering long values being entered (64 bits each, the max number of elements
* would be 5122512 MB/64bits = 67108864)
*/
Vector<Long> names = new Vector<Long>(67108865);
long newID=0L;
int count = 67108865;
int i = 0;
InputStreamReader input = new InputStreamReader(System.in);
Scanner reader = new Scanner(input);
public void addNames(){
do{
/* Adding unknown number of records to a list
* the user can enter more number of IDs than what the heap can support and
* exhaust the heap. Assume that the record ID is a 64 bit long value
*/
System.out.print(" To quit, enter -1\nEnter recordID: ");
newID = reader.nextLong();
//names are continued to be added without bothering about the size on the heap
names.addElement(newID);
System.out.println(newID);
i++;
}while (i<count || newID!=-1);
}
public static void main(String[] args) {
ShowHeapError demo = new ShowHeapError();
demo.addNames();
}
}
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