first commit

2024-01-15 20:14:10 +00:00
commit 8c81ee28b7
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+#BlueJ class context
+comment0.params=
+comment0.target=Auction()
+comment0.text=\n\ Create\ a\ new\ auction.\n
+comment1.params=description
+comment1.target=void\ enterLot(java.lang.String)
+comment1.text=\n\ Enter\ a\ new\ lot\ into\ the\ auction.\n\ @param\ description\ A\ description\ of\ the\ lot.\n
+comment2.params=
+comment2.target=void\ showLots()
+comment2.text=\n\ Show\ the\ full\ list\ of\ lots\ in\ this\ auction.\n
+comment3.params=lotNumber\ bidder\ value
+comment3.target=void\ makeABid(int,\ Person,\ long)
+comment3.text=\n\ Make\ a\ bid\ for\ a\ lot.\n\ A\ message\ is\ printed\ indicating\ whether\ the\ bid\ is\n\ successful\ or\ not.\n\ \n\ @param\ lotNumber\ The\ lot\ being\ bid\ for.\n\ @param\ bidder\ The\ person\ bidding\ for\ the\ lot.\n\ @param\ value\ \ The\ value\ of\ the\ bid.\n
+comment4.params=lotNumber
+comment4.target=Lot\ getLot(int)
+comment4.text=\n\ Return\ the\ lot\ with\ the\ given\ number.\ Return\ null\n\ if\ a\ lot\ with\ this\ number\ does\ not\ exist.\n\ @param\ lotNumber\ The\ number\ of\ the\ lot\ to\ return.\n
+numComments=5
@@ -0,0 +1,104 @@
+import java.util.ArrayList;
+
+/**
+ * A simple model of an auction.
+ * The auction maintains a list of lots of arbitrary length.
+ *
+ * @author David J. Barnes and Michael Kölling.
+ * @version 2016.02.29
+ */
+public class Auction
+{
+    // The list of Lots in this auction.
+    private ArrayList<Lot> lots;
+    // The number that will be given to the next lot entered
+    // into this auction.
+    private int nextLotNumber;
+
+    /**
+     * Create a new auction.
+     */
+    public Auction()
+    {
+        lots = new ArrayList<>();
+        nextLotNumber = 1;
+    }
+
+    /**
+     * Enter a new lot into the auction.
+     * @param description A description of the lot.
+     */
+    public void enterLot(String description)
+    {
+        lots.add(new Lot(nextLotNumber, description));
+        nextLotNumber++;
+    }
+
+    /**
+     * Show the full list of lots in this auction.
+     */
+    public void showLots()
+    {
+        for(Lot lot : lots) {
+            System.out.println(lot.toString());
+        }
+    }
+    
+    /**
+     * Make a bid for a lot.
+     * A message is printed indicating whether the bid is
+     * successful or not.
+     * 
+     * @param lotNumber The lot being bid for.
+     * @param bidder The person bidding for the lot.
+     * @param value  The value of the bid.
+     */
+    public void makeABid(int lotNumber, Person bidder, long value)
+    {
+        Lot selectedLot = getLot(lotNumber);
+        if(selectedLot != null) {
+            Bid bid = new Bid(bidder, value);
+            boolean successful = selectedLot.bidFor(bid);
+            if(successful) {
+                System.out.println("The bid for lot number " +
+                                   lotNumber + " was successful.");
+            }
+            else {
+                // Report which bid is higher.
+                Bid highestBid = selectedLot.getHighestBid();
+                System.out.println("Lot number: " + lotNumber +
+                                   " already has a bid of: " +
+                                   highestBid.getValue());
+            }
+        }
+    }
+
+    /**
+     * Return the lot with the given number. Return null
+     * if a lot with this number does not exist.
+     * @param lotNumber The number of the lot to return.
+     */
+    public Lot getLot(int lotNumber)
+    {
+        if((lotNumber >= 1) && (lotNumber < nextLotNumber)) {
+            // The number seems to be reasonable.
+            Lot selectedLot = lots.get(lotNumber - 1);
+            // Include a confidence check to be sure we have the
+            // right lot.
+            if(selectedLot.getNumber() != lotNumber) {
+                System.out.println("Internal error: Lot number " +
+                                   selectedLot.getNumber() +
+                                   " was returned instead of " +
+                                   lotNumber);
+                // Don't return an invalid lot.
+                selectedLot = null;
+            }
+            return selectedLot;
+        }
+        else {
+            System.out.println("Lot number: " + lotNumber +
+                               " does not exist.");
+            return null;
+        }
+    }
+}
@@ -0,0 +1,11 @@
+#BlueJ class context
+comment0.params=bidder\ value
+comment0.target=Bid(Person,\ long)
+comment0.text=\n\ Create\ a\ bid.\n\ @param\ bidder\ Who\ is\ bidding\ for\ the\ lot.\n\ @param\ value\ The\ value\ of\ the\ bid.\n
+comment1.params=
+comment1.target=Person\ getBidder()
+comment1.text=\n\ @return\ The\ bidder.\n
+comment2.params=
+comment2.target=long\ getValue()
+comment2.text=\n\ @return\ The\ value\ of\ the\ bid.\n
+numComments=3
@@ -0,0 +1,42 @@
+/**
+ * A class that models an auction bid.
+ * It contains a reference to the Person bidding and the amount bid.
+ * 
+ * @author David J. Barnes and Michael Kölling.
+ * @version 2016.02.29
+ */
+public class Bid
+{
+    // The person making the bid.
+    private final Person bidder;
+    // The value of the bid. This could be a large number so
+    // the long type has been used.
+    private final long value;
+
+    /**
+     * Create a bid.
+     * @param bidder Who is bidding for the lot.
+     * @param value The value of the bid.
+     */
+    public Bid(Person bidder, long value)
+    {
+        this.bidder = bidder;
+        this.value = value;
+    }
+
+    /**
+     * @return The bidder.
+     */
+    public Person getBidder()
+    {
+        return bidder;
+    }
+
+    /**
+     * @return The value of the bid.
+     */
+    public long getValue()
+    {
+        return value;
+    }
+}
@@ -0,0 +1,20 @@
+#BlueJ class context
+comment0.params=number\ description
+comment0.target=Lot(int,\ java.lang.String)
+comment0.text=\n\ Construct\ a\ Lot,\ setting\ its\ number\ and\ description.\n\ @param\ number\ The\ lot\ number.\n\ @param\ description\ A\ description\ of\ this\ lot.\n
+comment1.params=bid
+comment1.target=boolean\ bidFor(Bid)
+comment1.text=\n\ Attempt\ to\ bid\ for\ this\ lot.\ A\ successful\ bid\n\ must\ have\ a\ value\ higher\ than\ any\ existing\ bid.\n\ @param\ bid\ A\ new\ bid.\n\ @return\ true\ if\ successful,\ false\ otherwise\n
+comment2.params=
+comment2.target=java.lang.String\ toString()
+comment2.text=\n\ @return\ A\ string\ representation\ of\ this\ lot's\ details.\n
+comment3.params=
+comment3.target=int\ getNumber()
+comment3.text=\n\ @return\ The\ lot's\ number.\n
+comment4.params=
+comment4.target=java.lang.String\ getDescription()
+comment4.text=\n\ @return\ The\ lot's\ description.\n
+comment5.params=
+comment5.target=Bid\ getHighestBid()
+comment5.text=\n\ @return\ The\ highest\ bid\ for\ this\ lot.\n\ \ \ \ \ \ \ \ \ This\ could\ be\ null\ if\ there\ is\n\ \ \ \ \ \ \ \ \ no\ current\ bid.\n
+numComments=6
@@ -0,0 +1,94 @@
+/**
+ * A class to model an item (or set of items) in an
+ * auction: a lot.
+ * 
+ * @author David J. Barnes and Michael Kölling.
+ * @version 2016.02.29
+ */
+public class Lot
+{
+    // A unique identifying number.
+    private final int number;
+    // A description of the lot.
+    private String description;
+    // The current highest bid for this lot.
+    private Bid highestBid;
+
+    /**
+     * Construct a Lot, setting its number and description.
+     * @param number The lot number.
+     * @param description A description of this lot.
+     */
+    public Lot(int number, String description)
+    {
+        this.number = number;
+        this.description = description;
+        this.highestBid = null;
+    }
+
+    /**
+     * Attempt to bid for this lot. A successful bid
+     * must have a value higher than any existing bid.
+     * @param bid A new bid.
+     * @return true if successful, false otherwise
+     */
+    public boolean bidFor(Bid bid)
+    {
+        if(highestBid == null) {
+            // There is no previous bid.
+            highestBid = bid;
+            return true;
+        }
+        else if(bid.getValue() > highestBid.getValue()) {
+            // The bid is better than the previous one.
+            highestBid = bid;
+            return true;
+        }
+        else {
+            // The bid is not better.
+            return false;
+        }
+    }
+    
+    /**
+     * @return A string representation of this lot's details.
+     */
+    public String toString()
+    {
+        String details = number + ": " + description;
+        if(highestBid != null) {
+            details += "    Bid: " + 
+                       highestBid.getValue();
+        }
+        else {
+            details += "    (No bid)";
+        }
+        return details;
+    }
+
+    /**
+     * @return The lot's number.
+     */
+    public int getNumber()
+    {
+        return number;
+    }
+
+    /**
+     * @return The lot's description.
+     */
+    public String getDescription()
+    {
+        return description;
+    }
+
+    /**
+     * @return The highest bid for this lot.
+     *         This could be null if there is
+     *         no current bid.
+     */
+    public Bid getHighestBid()
+    {
+        return highestBid;
+    }
+}
@@ -0,0 +1,8 @@
+#BlueJ class context
+comment0.params=name
+comment0.target=Person(java.lang.String)
+comment0.text=\n\ Create\ a\ new\ person\ with\ the\ given\ name.\n\ @param\ name\ The\ person's\ name.\n
+comment1.params=
+comment1.target=java.lang.String\ getName()
+comment1.text=\n\ @return\ The\ person's\ name.\n
+numComments=2
@@ -0,0 +1,27 @@
+/**
+ * Maintain details of someone who participates in an auction.
+ * @author David J. Barnes and Michael Kölling.
+ * @version 2016.02.29
+ */
+public class Person
+{
+    // The name of this person.
+    private final String name;
+
+    /**
+     * Create a new person with the given name.
+     * @param name The person's name.
+     */
+    public Person(String name)
+    {
+        this.name = name;
+    }
+
+    /**
+     * @return The person's name.
+     */
+    public String getName()
+    {
+        return name;
+    }
+}
@@ -0,0 +1,26 @@
+Project: auction
+Authors: David J. Barnes and Michael Kölling
+
+This project is part of the supplementary material for
+chapter 4 of the book
+
+   Objects First with Java - A Practical Introduction using BlueJ
+   Sixth edition
+   David J. Barnes and Michael Kölling
+   Pearson Education, 2016
+
+Purpose of project: To demonstrate collections of objects
+How to start this project:
+    + Create an Auction object.
+
+    + Enter a few lots via its enterLot method. Only String
+    descriptions of the lots are required.
+
+    + Create one or more Person objects to represent bidders.
+
+    + Show the lots and decide on one to bid for. Make a note
+      of the lot number.
+
+    + Enter a bid for the lot by calling the makeABid method on
+      the Auction object. Pass the number of the lot, the Person
+      who is bidding, and the amount of the bid.
@@ -0,0 +1,83 @@
+#BlueJ package file
+dependency1.from=Auction
+dependency1.to=Lot
+dependency1.type=UsesDependency
+dependency2.from=Auction
+dependency2.to=Person
+dependency2.type=UsesDependency
+dependency3.from=Auction
+dependency3.to=Bid
+dependency3.type=UsesDependency
+dependency4.from=Lot
+dependency4.to=Bid
+dependency4.type=UsesDependency
+dependency5.from=Bid
+dependency5.to=Person
+dependency5.type=UsesDependency
+objectbench.height=76
+objectbench.width=774
+package.editor.height=429
+package.editor.width=666
+package.editor.x=70
+package.editor.y=80
+package.numDependencies=5
+package.numTargets=4
+package.showExtends=true
+package.showUses=true
+project.charset=UTF-8
+readme.editor.height=722
+readme.editor.width=842
+readme.editor.x=64
+readme.editor.y=23
+target1.editor.height=705
+target1.editor.width=876
+target1.editor.x=109
+target1.editor.y=42
+target1.height=60
+target1.name=Lot
+target1.naviview.expanded=true
+target1.showInterface=false
+target1.type=ClassTarget
+target1.typeParameters=
+target1.width=110
+target1.x=220
+target1.y=210
+target2.editor.height=720
+target2.editor.width=886
+target2.editor.x=55
+target2.editor.y=93
+target2.height=60
+target2.name=Auction
+target2.naviview.expanded=true
+target2.showInterface=false
+target2.type=ClassTarget
+target2.typeParameters=
+target2.width=110
+target2.x=100
+target2.y=80
+target3.editor.height=706
+target3.editor.width=926
+target3.editor.x=114
+target3.editor.y=60
+target3.height=60
+target3.name=Bid
+target3.naviview.expanded=true
+target3.showInterface=false
+target3.type=ClassTarget
+target3.typeParameters=
+target3.width=110
+target3.x=460
+target3.y=140
+target4.editor.height=711
+target4.editor.width=847
+target4.editor.x=114
+target4.editor.y=60
+target4.height=60
+target4.name=Person
+target4.naviview.expanded=true
+target4.showInterface=false
+target4.type=ClassTarget
+target4.typeParameters=
+target4.width=110
+target4.x=340
+target4.y=320