What is the is a and has a relation ship in oops concept in
java?
Answer Posted / b venkat reddy
The "is a" relationship is expressed with inheritance and
"has a" relationship expressed with composition.
Both inheritance and composition allow u to place sub-objects inside your new class.Two main techniques to code reuse are inheritance and composition.
Ex.: IS A ===>> house IS A building
class House {
.....
}
class Building extends House{
......
}
Ex.:HAS A ===>> house HAS A bathroom
class House {
Bathroom b = new Bathroom();
}
| Is This Answer Correct ? | 22 Yes | 5 No |
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Question 5 [15] Consider the following classes, illustrating the Strategy design pattern: import java.awt.*; abstract class Text { protected TextApplet tA; protected Text(TextApplet tApplet) { tA = tApplet; } abstract public void draw(Graphics g); } class PlainText extends Text { protected PlainText(TextApplet tApplet) { super(tApplet); } public void draw(Graphics g) { g.setColor(tA.getColor()); g.setFont(new Font("Sans-serif", Font.PLAIN, 12)); g.drawString(tA.getText(), 20, 20); } } class CodeText extends Text { protected CodeText(TextApplet tApplet) { super(tApplet); } public void draw(Graphics g) { g.setColor(tA.getColor()); g.setFont(new Font("Monospaced", Font.PLAIN, 12)); g.drawString(tA.getText(), 20, 20); } } public class TextApplet extends java.applet.Applet { protected Text text; protected String textVal; protected Color color; public String getText() { return textVal; } public Color getColor() { return color; } public void init() { textVal = getParameter("text"); String textStyle = getParameter("style"); String textColor = getParameter("color"); if (textStyle == "code") text = new CodeText(this); else text = new PlainText(this); if (textColor == "red") color = Color.RED; else if (textColor == "blue") color = Color.BLUE; else color = Color.BLACK; } public void paint(Graphics g) { text.draw(g); 10 } } The Text class is more complicated than it should be (there is too much coupling between the Text and TextApplet classes). By getting rid of the reference to a TextApplet object in the Text class and setting the colour in the paint() method, one could turn the Text class into an interface and simplify the strategy classes considerably. 5.1 Rewrite the Text and PlainText classes to do what is described above. (6) 5.2 Explain the consequent changes that are necessary to the TextApplet class. (4) 5.3 Write an additional strategy class called FancyText (to go with your simplified strategy classes) to allow fancy text to be displayed for the value "fancy" provided for the style parameter. It should use the font Font ("Serif", Font.ITALIC, 12). (3) 5.4 Explain what changes are necessary to the TextApplet class for this. (2)
public class Test { public static void main(String[] args) { int countA = 0; int countB = 0; int countC = 0; int countD = 0; int countE = 0; int countF = 0; int countG = 0; int countH = 0; int countI = 0; int countJ = 0; int countK = 0; int countL = 0; int countM = 0; int countN = 0; int countO = 0; int countP = 0; int countQ = 0; int countR = 0; int countS = 0; int countT = 0; int countU = 0; int countV = 0; int countW = 0; int countX = 0; int countY = 0; int countZ = 0; } } Can anybody tell me any alternate solution(like loop or something) to automate this initialization process. Ex:- for(char chr='A';chr<='Z'; chr++) { (int) String "count"+chr = 0; }
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