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Java Tutorial. Object-Oriented Programming Concepts Object –a representation of some item state  fields/members and should be encapsulated behavior 

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Presentation on theme: "Java Tutorial. Object-Oriented Programming Concepts Object –a representation of some item state  fields/members and should be encapsulated behavior "— Presentation transcript:

1 Java Tutorial

2 Object-Oriented Programming Concepts Object –a representation of some item state  fields/members and should be encapsulated behavior  methods Class –an implementation of some object Interface –the contract between classes Inheritance –a way to share common aspects of objects Package –a way to organize a set things together.

3 Object-Oriented Programming Concepts super class (common aspects) subclass (which extends the super class to specialize) extends

4 Language Basics literals (constants) variables –instance, class, local, parameters –data types (primitive and objects) –assignments and comparisons operators (unary, binary, ternary) expressions –comparisons a = "hello world"; b = "hello world"; (a == b)  TRUE a.equals(b)  TRUE i1 = new Integer(1); i2 = new Integer(1); (i1 == i2)  FALSE i1.equals(i2)  TRUE statements blocks control flow –if/then, switch, while, do/while, for, –branching - break, continue, return

5 Operator Precedence OperatorsPrecedence postfix expr++ expr-- unary ++expr --expr +expr -expr ~ ! multiplicative * / % additive + - shift > >>> relational = instanceof equality == != bitwise AND & bitwise exclusive OR ^ bitwise inclusive OR | logical AND && logical OR || ternary ? : assignment = += -= *= /= %= &= ^= |= >= >>>=

6 public class Factorial { /* The lowest value we can compute factorial for */ public final long FACTORIAL_LOW_VALUE = 0; // constant/literal /* The highest value we can compute factorial for */ public final long FACTORIAL_HIGH_VALUE = 20; // constant/literal /* Error message for out of range values */ public final String INVALID_FACTORIAL_VALUE = "Error: factorial can only be computed for values between " + FACTORIAL_LOW_VALUE + " to " + FACTORIAL_HIGH_VALUE + "."; /** * …. **/ public int factorial(int x) { int factorial = 1; // local variable to this method /* * By definition factorial can only be computed * for non-negative values, hence negative * values are not allowed. */ if((x FACTORIAL_HIGH_VALUE)) { throw new IllegalArgumentException(INVALID_FACTORIAL_VALUE); }/* if */ for(int i = 1; i <= x; ++i) { factorial *= i; }/* for */ return factorial; }/* public int factorial(...) */ }/* public class Factorial */

7 Classes, Parameters, and Objects Classes –Constructors when they are and not provided –Override vs Overloading Methods override – replaces overloading – augments –don’t get in the habit of using: static initialization blocks unnamed initialization blocks Parameters –passed by value referenced and value type parameters Objects –declaration –instantiation –initialization

8 Access Levels ModifierClassPackageSubclassWorld public YYYY protected YYYN no modifierYYNN private YNNN


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