Java Basics 1.01b

Garbage Collection

• Objects referenced created in heap memory
• As long as variable referenced, it’s retained
• When referenced expire, they’re eligible to be garbage collected
• Garbage Collector runs own thread
• Can’t force garbage collection
• OutOfMemoryError thrown if memory runs out

Expiration

• Variable to local functions or blocks expire when function is complete
• Set value to null

Tips for Managing Memory

• Minimize number of object created
• Runtime.*
  • Runtime.maxMemory()
  • Runtime.totalMemory()
  • Runtime.freeMemory()
• java -Xms256s HelloWorld - Initial heap size
• java -Xms256m HelloWorld - Max heap size
• java -Xms256n HelloWorld - Heap size for young generation objects