Difference between revisions of "Autoboxing"
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* Wrapper objects are '''immutable''' ! | * Wrapper objects are '''immutable''' ! | ||
* All have two constructors - one takes a primitive, other a string representation. | * 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. | + | * A valueOf() method also takes a string and returns a wrapper object in return. Also accepts an optional base (for Octal, Hex etc) |
* Wrapper to primitive - use the xxxValue() methods like intValue() and floatValue() | * Wrapper to primitive - use the xxxValue() methods like intValue() and floatValue() | ||
* String to primitive - e.g. Integer.parseInt("22"), Double.parseDouble("3.14"); | * String to primitive - e.g. Integer.parseInt("22"), Double.parseDouble("3.14"); | ||
| − | * toString() returns the string representation of | + | * toString() returns the string representation of the value represented by the wrapper. |
| + | * also base conversion is possible for Integer's and Long's - e.g. toBinaryString(), toHexString() and toOctalString(). | ||
| + | |||
[[Category:OCPJP]] | [[Category:OCPJP]] | ||
Revision as of 01:14, 13 August 2011
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. Also accepts an optional base (for Octal, Hex etc)
- 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 the value represented by the wrapper.
- also base conversion is possible for Integer's and Long's - e.g. toBinaryString(), toHexString() and toOctalString().
