Assigning “null” to objects in every application after their use

Question

• Do you always assign null to an object after its scope has been reached?

• Or do you rely on the JVM for garbage collection?

Answer 1

The one time I tend to use this practice is if I need to transform a large Collection in some early part of a method.

For example:

public void foo() {
  List trades = loadTrades();
  Map> tradesByDate = groupTradesByDate(trades);
  trades = null; // trades no longer required.

  // Apply business logic to tradesByDate map.
}

Obviously I could reduce the need for this by refactoring this into another method: Map>> loadTradesAndGroupByDate() so it really depends on circumstances / clarity of code.