Introduction to Computers and Java

Author: sharaf-qeshta

chapter_01/Exercise_01_06/Exercise_01_06.java

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+package chapter_01;
+
+/**
+ * 6. Write a statement or statements that can be used in a Java program to
+ * display the following on the screen:
+ *  Welcome
+ *  To
+ *  Java
+ *
+ *  @author Sharaf Qeshta
+ *  */
+
+public class Exercise_01_06
+{
+    public static void main(String[] args)
+    {
+        System.out.println("Welcome");
+        System.out.println("To");
+        System.out.println("Java");
+    }
+}

chapter_01/Exercise_01_07/Exercise_01_07.java

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+package chapter_01;
+
+/**
+ * 7. What would the following statements, when used in a Java program,
+ * display on the screen?
+ * int a = 10;
+ * int a2 = 100;
+ * System.out.println(a2);
+ * System.out.println (" is square of ");
+ * System.out.println(a);
+ *
+ * @author Sharaf Qeshta
+ * */
+public class Exercise_01_07
+{
+    public static void main(String[] args)
+    {
+        // 100
+        // is square of
+        // 10
+    }
+}

chapter_01/Exercise_01_08/Exercise_01_08.java

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+package chapter_01;
+
+import java.util.Scanner;
+
+/**
+ * 8. Write statements that can be used in a Java program to read two numbers,
+ * as entered at the keyboard, and display their difference on the screen.
+ *
+ * @author Sharaf Qeshta
+ * */
+public class Exercise_01_08
+{
+    public static void main(String[] args)
+    {
+        Scanner scanner = new Scanner(System.in);
+
+        int x = scanner.nextInt(), y = scanner.nextInt();
+
+        System.out.println(x  + " - " + y + " = " + (x - y));
+    }
+}

chapter_01/Exercise_01_09/Exercise_01_09.java

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+package chapter_01;
+
+/**
+ * 9. Given a person’s year of birth, the Election Wizard can compute the year
+ * in which they will be eligible to vote (assuming the eligibility age to be 18
+ * years). Write statements that can be used in a Java program to perform this
+ * computation for the Election Wizard.
+ *
+ * @author Sharaf Qeshta
+ * */
+public class Exercise_01_09
+{
+    public static void main(String[] args)
+    {
+        int yearOfBirth = 2001;
+
+        System.out.println(2022 - yearOfBirth);
+    }
+}

chapter_01/Exercise_01_10/Exercise_01_10.java

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+package chapter_01;
+
+import java.util.Scanner;
+
+/**
+ * 10. Write statements that can be used in a Java program to read two integers and
+ * display the number of integers that lie between them, including the integers
+ * themselves. For example, four integers are between 3 and 6: 3, 4, 5, and 6.
+ *
+ * @author Sharaf Qeshta
+ * */
+public class Exercise_01_10
+{
+    public static void main(String[] args)
+    {
+        Scanner scanner = new Scanner(System.in);
+
+        System.out.print("Enter two integers: ");
+        int x = scanner.nextInt(), y = scanner.nextInt();
+
+        int integersCount = y - x + 1;
+
+        System.out.println("Integers count lie between " + x + " and " + y + " is " + integersCount);
+    }
+}

chapter_01/Exercise_01_11/Exercise_01_11.java

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+package chapter_01;
+
+/**
+ * 11. A memory address starts with 2313. Each subsequent value uses three
+ * bytes as location. For instance, the second value takes memory
+ * addresses 2316, 2317, and 2318. What memory addresses will be taken
+ * by:
+ * a. 5th value? b. 10th value? c. 13th value?
+ *
+ * @author Sharaf Qeshta
+ * */
+
+public class Exercise_01_11
+{
+    // we can extract a pattern
+    // nth value last memory location is (n * 3) + 2312
+    // 1st value last memory location is 3 + 2312 = 2315
+    // 2nd value last memory location is 6 + 2312 = 2318
+    // and so on
+
+    // a. 5th
+    // 15 + 2312 = 2327
+    // 2325, 2326, 2327
+
+    // b. 10th
+    // 30 + 2312 = 2342
+    // 2340, 2341, 2342
+
+    // c. 13th
+    // 39 + 2312 = 2351
+    // 2349, 2350, 2351
+}

chapter_01/Exercise_01_12/Exercise_01_12.java

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+package chapter_01;
+
+/**
+ * 12. Find the documentation for the Java Class Library on the Oracle® Web site.
+ * (At this writing, the link to this documentation is https://docs.oracle.com/
+ * javase/8/docs/api/.) Then find the description for the class Scanner. How
+ * many methods are described in the section entitled “Method Summary”?
+ *
+ * @author Sharaf Qeshta
+ * */
+public class Exercise_01_12
+{
+    // 55 methods exist in the Scanner class
+}

chapter_01/Exercise_01_13/Exercise_01_13.java

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+package chapter_01;
+
+/**
+ * 13. Self-Test Question 27 asked you to think of some attributes for a song
+ * object. What attributes would you want for an object that represents a play
+ * list containing many songs?
+ *
+ * @author Sharaf Qeshta
+ * */
+public class Exercise_01_13
+{
+    // an array of songs
+    // current playing song
+    // loop or not
+}

chapter_01/Exercise_01_14/Exercise_01_14.java

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+package chapter_01;
+
+/**
+ * 14. What behaviors might a song have? What behaviors might a play list have?
+ * Contrast the difference in behavior between the two kinds of objects.
+ *
+ * @author Sharaf Qeshta
+ * */
+
+public class Exercise_01_14
+{
+    // song
+    // 1. play
+    // 2. pause
+    // 3. seek
+
+    // playlist
+    // 1. play
+    // 2. play specific song
+    // 3. set the loop
+}

chapter_01/Exercise_01_15/Exercise_01_15.java

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+package chapter_01;
+
+/**
+ * 15. What attributes and behaviors would an object representing a mobile sim
+ * card have?
+ *
+ * @author Sharaf Qeshta
+ * */
+public class Exercise_01_15
+{
+    // attributes
+    // 1. card number
+    // 2. list of contacts
+    // 3. service provider
+
+    // behaviors
+    // 1. make a call
+    // 2. end a call
+    // 3. store a contact
+}

chapter_01/Exercise_01_16/Exercise_01_16.java

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+package chapter_01;
+
+/**
+ * 16. Suppose that you have a number x that is greater than 1. Write an algorithm
+ * that computes the largest integer k such that 2^k
+ *  is less than or equal to x.
+ *
+ *  @author Sharaf Qeshta
+ *  */
+public class Exercise_01_16
+{
+    // let k = 1
+    // increment the k by one until 2^k > x
+    // then the number is (k-1)
+}

chapter_01/Exercise_01_17/Exercise_01_17.java

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+package chapter_01;
+
+/**
+ * 17. Write an algorithm that finds the minimum value in a list of values
+ *
+ * @author Sharaf Qeshta
+ * */
+public class Exercise_01_17
+{
+    // let min = the first element in the list
+    // for each x in the list if x < min then
+    // min = x
+    // when you finish then the minimum value will be
+    // the value stored in min
+}

chapter_01/Exercise_01_18/Exercise_01_18.java

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+package chapter_01;
+
+import javafx.application.Application;
+import javafx.scene.Scene;
+import javafx.scene.layout.Pane;
+import javafx.scene.paint.Color;
+import javafx.scene.shape.Circle;
+import javafx.stage.Stage;
+
+/**
+ * 18. Write statements that can be used in a JavaFX application to draw a dart
+ * board showing concentric circular rings and a bull’s eye. (The bull’s eye
+ * should be a filled circle.)
+ *
+ * @author Sharaf Qeshta
+ * */
+public class Exercise_01_18 extends Application
+{
+    public static void main(String[] args)
+    {
+        launch(args);
+    }
+
+    @Override
+    public void start(Stage primaryStage)
+    {
+        Pane pane = new Pane();
+
+        // bull`s eye
+        Circle bullEye = new Circle(250, 250, 5);
+        bullEye.setFill(Color.BLACK);
+
+        // 6 circles around the bull`s eye
+        Circle circle1 = new Circle(250, 250, 15, Color.WHITE);
+        circle1.setStroke(Color.BLACK);
+
+        Circle circle2 = new Circle(250, 250, 25, Color.WHITE);
+        circle2.setStroke(Color.BLACK);
+
+        Circle circle3 = new Circle(250, 250, 35, Color.WHITE);
+        circle3.setStroke(Color.BLACK);
+
+        Circle circle4 = new Circle(250, 250, 45, Color.WHITE);
+        circle4.setStroke(Color.BLACK);
+
+        Circle circle5 = new Circle(250, 250, 55, Color.WHITE);
+        circle5.setStroke(Color.BLACK);
+
+        Circle circle6 = new Circle(250, 250, 65, Color.WHITE);
+        circle6.setStroke(Color.BLACK);
+
+        pane.getChildren().addAll(circle6, circle5, circle4,
+                circle3, circle2, circle1, bullEye);
+
+        Scene scene = new Scene(pane, 500, 500);
+        primaryStage.setTitle("Exercise_01_18");
+        primaryStage.setScene(scene);
+        primaryStage.show();
+    }
+}

chapter_01/Exercise_01_18/Exercise_01_18.png

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+package chapter_01;
+
+import javafx.application.Application;
+import javafx.scene.Group;
+import javafx.scene.Scene;
+import javafx.scene.canvas.Canvas;
+import javafx.scene.canvas.GraphicsContext;
+import javafx.stage.Stage;
+
+
+/**
+ * 19. Find the documentation for the class Graphics Context in the JavaFX Class
+ * Library. (See Exercise 12.) Learn how to use the method strokeRect. Then
+ * write statements that can be used in a JavaFX application to draw a square
+ * containing a circle. The circle’s diameter and the square’s side should be
+ * equal in size.
+ *
+ * @author Sharaf Qeshta
+ * */
+public class Exercise_01_19 extends Application
+{
+
+    public static void main(String[] args)
+    {
+        launch(args);
+    }
+
+    @Override
+    public void start(Stage primaryStage)
+    {
+        // https://docs.oracle.com/javase/8/javafx/api/javafx/scene/canvas/GraphicsContext.html#strokeRect-double-double-double-double-
+        Group root = new Group();
+        Canvas canvas = new Canvas(500, 500);
+        GraphicsContext gc = canvas.getGraphicsContext2D();
+
+        // rectangle
+        gc.strokeRect(245, 245, 100, 100);
+
+        // circle
+        gc.strokeOval(245, 245, 100, 100);
+        root.getChildren().add(canvas);
+
+        Scene scene = new Scene(root, 500, 500);
+        primaryStage.setTitle("Exercise_01_19");
+        primaryStage.setScene(scene);
+        primaryStage.show();
+    }
+}