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JAVA API Classes

JAVA API Classes. - Scanner - String - wrapper classes (especially Integer) - NumberFormat - DecimalFormat - ArrayList - File output. Wrapper Class. Boolean, byte, char, double, float, int, long, short void. Object oriented vs. efficiency.

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JAVA API Classes

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  1. JAVA API Classes - Scanner - String - wrapper classes (especially Integer) - NumberFormat - DecimalFormat - ArrayList - File output

  2. Wrapper Class • Boolean, byte, char, double, float, int, long, short • void Object oriented vs. efficiency numerical values are needed but objects instead of primitives are required

  3. Wrapper Classes • Primitive data types • boolean • byte • char • double • float • int • long • short • void java.lang.Boolean java.lang.Byte java.lang.Char java.lang.Double java.lang.Float java.lang.Integer java.lang.Long java.lang.Short Java.lang.Void

  4. double d = 5.0; Double aD = new Double(d); double r = aD.doubleValue();

  5. NumberFormat class • java.text package • provide generic formatting capabilities • static : do not need to instantiate

  6. Decimal Format • instantiate using new operator

  7. printf method • print • println • printf (format string, value) • System.out.printf(“ ID: %5d\tName: %s”, id, name)

  8. ArrayList • java.util package • it can dynamically grow and shrink • no type : stores a list of references, meaning primitive value -> wrapper class

  9. Output to file

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