Objects First with Java - A Practical Introduction using BlueJ, David J. Barnes, Michael Kölling 2

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5 %,, -. / %+!01#2 Objects First with Java - A Practical Introduction using BlueJ, David J. Barnes, Michael Kölling 5

6 boolean finished = false; while(!finished) { do something } if(exit condition) { finished = true; } else { do something more } Objects First with Java - A Practical Introduction using BlueJ, David J. Barnes, Michael Kölling 6

7 String input = reader.getinput();... String response = responder.generateresponse(); System.out.println(response); Objects First with Java - A Practical Introduction using BlueJ, David J. Barnes, Michael Kölling 7

8 %- String input = reader.getinput(); if(input.startswith("bye")) { finished = true; } '' 5 Objects First with Java - A Practical Introduction using BlueJ, David J. Barnes, Michael Kölling 8

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12 9 /- 2" %& " Objects First with Java - A Practical Introduction using BlueJ, David J. Barnes, Michael Kölling 12

13 & 9&", ) import java.util.arraylist; & ) import java.util.*; Objects First with Java - A Practical Introduction using BlueJ, David J. Barnes, Michael Kölling 13

14 ,),: if(input == "bye") {... } tests identity if(input.equals("bye")) {... } tests equality,/ 2' '.equals Objects First with Java - A Practical Introduction using BlueJ, David J. Barnes, Michael Kölling 14

15 :! /;,2) ) Fred ) Jill person1 person2 person1 == person2? Objects First with Java - A Practical Introduction using BlueJ, David J. Barnes, Michael Kölling 15

16 :< /;,2) ) Fred ) Fred person1 person2 person1 == person2? Objects First with Java - A Practical Introduction using BlueJ, David J. Barnes, Michael Kölling 16

17 := /;,2) ) Fred ) Fred person1 person2 person1 == person2? Objects First with Java - A Practical Introduction using BlueJ, David J. Barnes, Michael Kölling 17

18 :/,2 String input = reader.getinput(); if(input == "bye") {... } >> ), "bye" ), "bye" input / 2? Objects First with Java - A Practical Introduction using BlueJ, David J. Barnes, Michael Kölling 18

19 :/,2 String input = reader.getinput(); if(input.equals("bye")) {... } : ), "bye" ), "bye" input? Objects First with Java - A Practical Introduction using BlueJ, David J. Barnes, Michael Kölling 19

20 $ %Random import java.util.random;... Random randomgenerator = new Random();... int index1 = randomgenerator.nextint(); int index2 = randomgenerator.nextint(100); Objects First with Java - A Practical Introduction using BlueJ, David J. Barnes, Michael Kölling 20

21 @ public Responder() { randomgenerator = new Random(); responses = new ArrayList(); fillresponses(); } public String generateresponse() { int index = randomgenerator.nextint(responses.size()); return (String) responses.get(index); } public void fillresponses()... Objects First with Java - A Practical Introduction using BlueJ, David J. Barnes, Michael Kölling 21

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24 HashMap phonebook = new HashMap(); phonebook.put("charles Nguyen", "(531) "); phonebook.put("lisa Jones", "(402) "); phonebook.put("william H. Smith", "(998) "); String number = (String)phoneBook.get("Lisa Jones"); System.out.println(number); Objects First with Java - A Practical Introduction using BlueJ, David J. Barnes, Michael Kölling 24

25 import java.util.hashset; import java.util.iterator;... HashSet myset = new HashSet(); myset.add("one"); myset.add("two"); myset.add("three"); Iterator it = myset.iterator(); while(it.hasnext()) { call it.next() to get the next object do something with that object } Objects First with Java - A Practical Introduction using BlueJ, David J. Barnes, Michael Kölling 25

26 %&., public HashSet getinput() { System.out.print("> "); String inputline = readinputline().trim().tolowercase(); StringTokenizer tokenizer = new StringTokenizer(inputLine); HashSet words = new HashSet(); } while(tokenizer.hasmoretokens()) { words.add(tokenizer.nexttoken()); } return words; Objects First with Java - A Practical Introduction using BlueJ, David J. Barnes, Michael Kölling 26

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30 9 ) /** * The Responder class represents a response * generator object. It is used to generate an * automatic response. * Michael Kölling and David J. Barnes 1.0 (1.Feb.2002) */ Objects First with Java - A Practical Introduction using BlueJ, David J. Barnes, Michael Kölling 30

31 ) /** * Read a line of text from standard input (the text * terminal), and return it as a set of words. * prompt A prompt to print to screen. A set of Strings, where each String is * one of the words typed by the user */ public HashSet getinput(string prompt) {... } Objects First with Java - A Practical Introduction using BlueJ, David J. Barnes, Michael Kölling 31

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35 9 private static final int gravity = 3; private) + static) final) Objects First with Java - A Practical Introduction using BlueJ, David J. Barnes, Michael Kölling 35

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