diff --git a/README.md b/README.md index 4f153b0..cb39cb0 100644 --- a/README.md +++ b/README.md @@ -17,12 +17,15 @@ Work through all these exercises. You edit this file with your answers for these ### Exercise 2.2 * What value is returned if you check the machine’s balance after it has printed a ticket? +The balance returned is 0 ### Exercise 2.3 * Experiment with inserting different amounts of money before printing tickets. - * Do you notice anything strange about the machine’s behavior? - * What happens if you insert too much money into the machine – do you receive any refund? + * Do you notice anything strange about the machine’s behavior? Yes + * What happens if you insert too much money into the machine – do you receive any refund? + No, there is no refund. * What happens if you do not insert enough and then try to print a ticket? + The machine still prints a ticket and resets the balance to zero ### Exercise 2.4 * Try to obtain a good understanding of a ticket machine’s behavior by interacting with it on the object bench before we start looking at how the `TicketMachine` class is implemented in the next section. @@ -30,11 +33,15 @@ Work through all these exercises. You edit this file with your answers for these ### Exercise 2.5 * Create another ticket machine for tickets of a different price. * Buy a ticket from that machine. - * Does the printed ticket look different? + * Does the printed ticket look different? Yes, the ticket price value has changed ### Exercise 2.6 * Write out what you think the outer wrappers of the `Student` and `LabClass` classes might look like – do not worry about the inner part. +public class Student { } + +public class LabClass { } + ### Exercise 2.7 Does it matter whether we write
`public class TicketMachine`
@@ -42,38 +49,49 @@ or
`class public TicketMachine`
in the outer wrapper of a class? +Yes, public must come before class + * Edit the source of the `TicketMachine` class to make the change and then close the editor window. - * Do you notice a change in the class diagram? - * What error message do you get when you now press the compile button? - * Do you think this message clearly explains what is wrong? + * Do you notice a change in the class diagram? Yes, the class turns red + * What error message do you get when you now press the compile button? Identifier expected error + * Do you think this message clearly explains what is wrong? No ### Exercise 2.8 * Check whether or not it is possible to leave out the word `public` from the outer wrapper of the `TicketMachine` class. +It is possible + ### Exercise 2.9 * From your earlier experimentation with the ticket machine objects within BlueJ you can probably remember the names of some of the methods – `printTicket`, for instance. * Look at the class definition in Code 2.1 and use this knowledge, along with the additional information about ordering we have given you, to try to make a list of the names of the fields, constructors, and methods in the `TicketMachine` class. * Hint: There is only one constructor in the class. + fields : balance, price, total, ticketNumber + constrocturs: TicketMachine(int ticketPrice) + methods: insertMoney(int amount), printTicket(), getBalance(), insertMoney(int amount) + + ### Exercise 2.10 -* Do you notice any features of the constructor that make it significantly different from the other methods of the class? +* Do you notice any features of the constructor that make it significantly different from the other methods of the class + +It has no return type, it is Capitalised, It's name is the same as the class ### Exercise 2.11 * What do you think is the type of each of the following fields? ```java -private int count; -private Student representative; -private Server host; +private int count; //Primitive Integer +private Student representative; //Object of type Student +private Server host; //Object of type Server ``` ### Exercise 2.12 * What are the names of the following fields? ```java -private boolean alive; -private Person tutor; -private Game game; +private boolean alive; //Var name is "alive" +private Person tutor; //Var name is "tutor" +private Game game; //Var name is "game" ``` ### Exercise 2.13 @@ -82,15 +100,15 @@ In the following field declaration from the TicketMachine class
```java private int price; ``` -does it matter which order the three words appear in? +does it matter which order the three words appear in? Yes * Edit the `TicketMachine` class to try different orderings. After each change, close the editor. * Does the appearance of the class diagram after each change give you a clue as to whether or not other orderings are -possible? +possible? Other orderings are not possible, the class diagram turns red to signify that there is an error * Check by pressing the compile button to see if there is an error message. * Make sure that you reinstantiate the original version after your experiments! ### Exercise 2.14 -* Is it always necessary to have a semicolon at the end of a field declaration? +* Is it always necessary to have a semicolon at the end of a field declaration? Yes * Once again, experiment via the editor. * The rule you will learn here is an important one, so be sure to remember it. @@ -98,20 +116,26 @@ possible? ### Exercise 2.15 * Write in full the declaration for a field of type `int` whose name is `status`. +```Java +int status; +``` + ### Exercise 2.16 * To what class does the following constructor belong? ``` public Student(String name) ``` +The class Student ### Exercise 2.17 * How many parameters does the following constructor have and what are their types? ``` public Book(String title, double price) ``` +Two, a string and double. ### Exercise 2.18 -* Can you guess what types some of the `Book` class’s fields might be? -* Can you assume anything about the names of its fields? +* Can you guess what types some of the `Book` class’s fields might be? string and a double +* Can you assume anything about the names of its fields? Perhaps title and price READ upto and INCLUDING section 2.15 of this chapter. diff --git a/TicketMachine.java b/TicketMachine.java index 630c4ea..00a84bc 100644 --- a/TicketMachine.java +++ b/TicketMachine.java @@ -9,7 +9,7 @@ * @author David J. Barnes and Michael Kolling * @version 2008.03.30 */ -public class TicketMachine +class TicketMachine { // The price of a ticket from this machine. private Integer price; diff --git a/bluej.pkg b/bluej.pkg index bf25784..767984c 100644 --- a/bluej.pkg +++ b/bluej.pkg @@ -1,20 +1,27 @@ #BlueJ package file -editor.fx.0.height=722 -editor.fx.0.width=800 -editor.fx.0.x=709 -editor.fx.0.y=113 +dependency1.from=TicketMachineTest +dependency1.to=TicketMachine +dependency1.type=UsesDependency +editor.fx.0.height=977 +editor.fx.0.width=922 +editor.fx.0.x=-200 +editor.fx.0.y=-1057 +editor.fx.1.height=977 +editor.fx.1.width=896 +editor.fx.1.x=723 +editor.fx.1.y=-1057 objectbench.height=101 -objectbench.width=461 +objectbench.width=508 package.divider.horizontal=0.6 -package.divider.vertical=0.8007380073800738 -package.editor.height=427 -package.editor.width=674 -package.editor.x=1067 -package.editor.y=119 -package.frame.height=600 -package.frame.width=800 -package.numDependencies=0 -package.numTargets=1 +package.divider.vertical=0.8497913769123783 +package.editor.height=604 +package.editor.width=406 +package.editor.x=2 +package.editor.y=23 +package.frame.height=777 +package.frame.width=532 +package.numDependencies=1 +package.numTargets=2 package.showExtends=true package.showUses=true project.charset=UTF-8 @@ -24,9 +31,16 @@ readme.width=47 readme.x=10 readme.y=10 target1.height=50 -target1.name=TicketMachine +target1.name=TicketMachineTest target1.showInterface=false -target1.type=ClassTarget -target1.width=120 -target1.x=80 -target1.y=50 +target1.type=UnitTestTargetJunit4 +target1.width=140 +target1.x=10 +target1.y=110 +target2.height=50 +target2.name=TicketMachine +target2.showInterface=false +target2.type=ClassTarget +target2.width=120 +target2.x=80 +target2.y=50 diff --git a/package.bluej b/package.bluej index bf25784..767984c 100644 --- a/package.bluej +++ b/package.bluej @@ -1,20 +1,27 @@ #BlueJ package file -editor.fx.0.height=722 -editor.fx.0.width=800 -editor.fx.0.x=709 -editor.fx.0.y=113 +dependency1.from=TicketMachineTest +dependency1.to=TicketMachine +dependency1.type=UsesDependency +editor.fx.0.height=977 +editor.fx.0.width=922 +editor.fx.0.x=-200 +editor.fx.0.y=-1057 +editor.fx.1.height=977 +editor.fx.1.width=896 +editor.fx.1.x=723 +editor.fx.1.y=-1057 objectbench.height=101 -objectbench.width=461 +objectbench.width=508 package.divider.horizontal=0.6 -package.divider.vertical=0.8007380073800738 -package.editor.height=427 -package.editor.width=674 -package.editor.x=1067 -package.editor.y=119 -package.frame.height=600 -package.frame.width=800 -package.numDependencies=0 -package.numTargets=1 +package.divider.vertical=0.8497913769123783 +package.editor.height=604 +package.editor.width=406 +package.editor.x=2 +package.editor.y=23 +package.frame.height=777 +package.frame.width=532 +package.numDependencies=1 +package.numTargets=2 package.showExtends=true package.showUses=true project.charset=UTF-8 @@ -24,9 +31,16 @@ readme.width=47 readme.x=10 readme.y=10 target1.height=50 -target1.name=TicketMachine +target1.name=TicketMachineTest target1.showInterface=false -target1.type=ClassTarget -target1.width=120 -target1.x=80 -target1.y=50 +target1.type=UnitTestTargetJunit4 +target1.width=140 +target1.x=10 +target1.y=110 +target2.height=50 +target2.name=TicketMachine +target2.showInterface=false +target2.type=ClassTarget +target2.width=120 +target2.x=80 +target2.y=50