Primitive Values Vs ObjectsWrapper ClassesOther Wrapper ClassesStoring Primitive Values/VariablesStoring Objects Values/VariablesStructured ObjectsSlide 7InheritanceSlide 9Assignment of Object VariablesSlide 11Slide 12Slide 13== for ObjectsSlide 15== Vs Equal for Strings== Vs equals() for ObjectsPrimitive Values Vs Objects•Wrapper Classes•Memory Representation of Primitive Values Vs Objects–Pointers•Equal Vs ==•Sharing of Objects•Garbage Collectionvector.elementAt(3)5new Integer(5)Wrapper ClassesAStringDatabaseAStringHistoryStringObjectintbooleanchar doublewrapper class“Joe Doe”.toString()5.toString()Vector vector = new Vector()vector.addElement(“Joe Doe”)vector.addElement(5)vector.addElement(new Integer(5))(new Integer(5)).toString()vector.elementAt(3).intValue()NumberIntegerDoublewrapper classOther Wrapper Classes•Double–public Double(double value)–public double doubleValue()•Boolean–public Boolean(boolean value)–public boolean booleanValue()•Character–public Character(char value)–public char charValue()•Float, Short, LongStoring Primitive Values/Variables55.55.548double d52int i80double e8 5.5 5.55165int i = 5;memory addressdouble d = 5.5;same sizesame, double sizedouble e = d;Storing Objects Values/Variables1685.5Double@8860Integer I516Integer@1648Double DInteger I = new Integer(5)Double D = new Double(5.5)memory addressdifferent sizesvariables same sizeStructured Objectspublic class APoint implements Point {int x, y; public APoint (int initX, int initY) { x = initX; y = initY;}public int getX() {return x};public void setX(int newVal) {x = newVal;}public int getY() {return y};public void setY(int newVal) {y = newVal;}}Structured Objects16805.5Double@8860Integer I516Integer@1696Point p5010080APoint@8048Double Dpublic class APoint implements Point { // instance vars int x, y; //methods …}Point p = new APoint(50, 100)Inheritancepublic class ABoundedPoint extends APoint { APoint upperLeftCorner, lowerRightCorner; public ABoundedPoint (int initX, int initY, Point initUpperLeftCorner, Point initLowerRightCorner) { super(initX, initY); upperLeftCorner = initUpperLeftCorner; lowerRightCorner = initLowerRightCorner; } …}}Superclass ConstructorInheritancepublic class APoint implements Point { int x, y; …}new ABoundedPoint(75, 75, new APoint(50,50), new APoint(100,100) )8165050APoint@8848ABoundedPoint@4810016APoint@161007575public class ABoundedPoint extends APoint { Point upperLeftCorner ; Point lowerRightCorner; …}Assignment of Object VariablesPoint p1 = new APoint(50, 50); Point p2 = p1;5050APoint@88816Point p1848Point p2P1 [email protected](100);Assignment of Object VariablesPoint p1 = new APoint(50, 50); Point p2 = p1;10050APoint@88168Point p1848Point p2p1.setX(100);p2.getX() 100 P1 P2APoint@8p1 = new APoint(200,200);Assignment of Object Variables10050200APoint@86420016488Point p1APoint@648 Point p264Point p2 = p1;p1 = new APoint(200,200);p2.getX() 100 p1.setX(100);p2.getX() 100 Point p1 = new APoint(50, 50); P1 P2APoint@64 APoint@8p2 = p1;Assignment of Object Variables10050200APoint@86420016488Point p1APoint@6464 Point p264Point p2 = p1;p1 = new APoint(200,200);p2.getX() 100 p2 = p1;p2.getX() 200 p1.setX(100);p2.getX() 100 Point p1 = new APoint(50, 50); P1 P2APoint@64 APoint@8 Garbage collected== for Objects200200200APoint@86420016488Point p1APoint@648 Point p264Point p2 = new APoint(200, 200)Point p1 = new APoint(200, 200); P1 P2APoint@64 APoint@8p2 == p2 false Same physical object?== for Objects200200APoint@8816488Point p18 Point p2Point p2 = p1;Point p1 = new APoint(200, 200); p2 == p2 true P1 P2APoint@8== Vs Equal for StringsJoe DoeJoe DoeString@86416488String s1String@648 String s264String s2 = “Joe Doe”String s1 = “Joe Doe”; S1 S2String@64 String@8s1 == s2 false s1.equals(s2) true== Vs equals() for Objects200200200APoint@86420016488Point p1APoint@648 Point p264Point p2 = new APoint(200, 200)Point p1 = new APoint(200, 200); p2 == p2 false public boolean equals(Point otherPoint) { return x == otherPoint.getX() && y == otherPoint.getY();}p1.equals(p2)
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