Autoboxing

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Wrapper Classes

  • Wrapper classes for primtives are a mechanism to include primitives in activities reserved for objects. e.g. being part of Collections.
  • Wrapper objects are immutable !
  • All have two constructors - one takes a primitive, other a string representation.
  • A valueOf() method also takes a string and returns a wrapper object in return.
  • Wrapper to primitive - use the xxxValue() methods like intValue() and floatValue()
  • String to primitive - e.g. Integer.parseInt("22"), Double.parseDouble("3.14");
  • toString() returns the string representation of a primitive.