Primitive Wrappers
- 2. Prime Benefits Provides a way of wrapping primitive values in an object so that a primitive can be treated as an object. To provide a set of utility methods for primitives.
- 3. Situations when required When primitives are required to be added to a collection object. When we want to return a primitive from a method that returns an object. When converting primitives to and from String objects. When converting primitives & String objects to and from different bases like binary, octal & hexadecimal.
- 5. Creating Objects Integer i1 = new Integer(5); Integer i2 = new Integer(“5”); Float f1 = new Float(5.6f); Float f2 = new Float(“5.6f”); Double d1 = new Double(6.7); Double d2 = new Double(“6.7”); Character c = new Character(‘a’); Boolean b1 = new Boolean(true); Boolean b2 = new Boolean(“true”); Boolean b3 = new Boolean(“TrUe”);
- 6. Creating Objects contd. valueOf() methods Integer i1 = Integer.valueOf(“101”,2); Integer i2 = Integer.valueOf(“F”,16); Integer i3 = Integer.valueOf(“012”,8); Integer i4 = Integer.valueOf(“102”);
- 7. Class Hierarchy java.lang.Object java.lang.Number java.lang.Byte java.lang.Long java.lang.Float java.lang.Integer java.lang.Short java.lang.Boolean java.lang.Double java.lang.Character
- 8. java.lang.Number public java.lang.Number(); public abstract int intValue(); public abstract long longValue(); public abstract float floatValue(); public abstract double doubleValue(); public byte byteValue(); public short shortValue(); java.lang.Object java.lang.Number java.io.Serializable
- 9. Wrapper Conversion Utilities using methods from Number class
- 10. Wrapper Conversion Utilities contd. Integer i = new Integer(200); byte b = i.byteValue(); short s = i.shortValue(); long l = i.longValue(); float fl = i.floatValue(); Float f = new Float(5.6f); byte b2 = f.byteValue(); short s2 = f.shortValue(); int i2 = f.intValue(); Stack Heap 5.6 200 i f i2 b2 s2 fl l s b
- 11. Wrapper Conversion Utilities contd.
- 12. Boxing & Unboxing Integer ref = new Integer(15); Encapsulating the primitive value in the respective Wrapper object is called boxing or Wrapping. int a = ref.intValue() + 5; Getting the encapsulated value out of the object is called unboxing or unwrapping .
- 13. AutoBoxing & AutoUnboxing Supported by jdk1.5+ Integer i = 67; automatically translated into following code by the compiler. Integer i = new Integer(67); // so called AutoBoxing int a = i + 10; automatically translated into following code by the compiler. int a = i.intValue() + 10; // so called AutoUnboxing