What is heap size in Java?

Java heap is the heap size allocated to JVM applications which takes care of the new objects being created. If the objects being created exceed the heap size, it will throw an error saying memoryOutof Bound Java's default heap size limit is 128MB. If you need more than this, you should use the -Xms and -Xmx command line arguments when launching your program:
java -Xms -Xmx We can also give like in this format also.format is : -mx256m..Sometimes it will show error if you are using java -Xms -Xmx format..In that case use -mx256m this.value can be changed..