Add files via upload

Author: munzirkalimahmed

Java/Animal02.class

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+public class Animal02 {
+
+  int legs = 4;     // class member
+
+  // 01 add a method
+   public int getLegs() {
+    return this.legs;
+  }
+
+  void constructsTest() {
+    int x = 5;
+    if (x == 5)
+      System.out.println("X is 5");
+
+    for(int i = 0; i < 3; i++)
+      System.out.println("Looping:" + i);
+  }
+
+  public static void main(String args[]) {
+    System.out.println("Main function called ... ");
+    Animal02 a = new Animal02();    // create an instance
+    System.out.println("Legs: " + a.legs);
+
+    // add call to method
+    System.out.println("Legs from method: " + a.getLegs());
+
+
+    a.constructsTest();
+  }
+}
+

Java/Animal02.java

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+public class Animal04 {
+
+  public Animal04() {
+      // Constructor
+      System.out.println("Animal class created...");
+  }
+
+  // java doesn't have a destructor
+
+  public static void main(String args[]) {
+    System.out.println("Main function called ... ");
+
+    Animal04 a = new Animal04();
+  }
+}

Java/Animal04.class

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+public class Animal05 {
+  int legs;
+
+  // String msg = "Test message";  // 03 add this and change msg below
+
+  public int getLegs() {    // 02 make this private
+    return this.legs;
+  }
+
+  public void printLegCount(String msg) {
+    System.out.println(msg + ": " + getLegs());
+  }
+
+  // java doesn't have a destructor
+
+  public static void main(String args[]) {
+    Animal05 a = new Animal05();
+
+    a.printLegCount("Legs are");
+
+    // 01
+    a.legs += 1;
+    a.printLegCount("Legs are");
+  }
+}

Java/Animal04.java

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+public class Intro01 {
+   public static void main(String args[]) {
+   
+   	System.out.println("Hello world!");
+   	System.out.println(args[0]);
+   	System.out.println(args[1]);
+   }
+}

Java/Animal05.class

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+public class Math06 {
+
+  public double sqrt(int x, double guess) {
+    System.out.println("Calculating sqrt of " + x + " starting with guess: " + guess);
+    return 1.0;
+  }
+
+  // Overloaded method -- for 'default' arguments
+  public double sqrt(int x) {
+    double guess = 1.0;
+    return sqrt(x, guess);
+  }
+
+  public double sqrt(double x) {
+    double guess = 1.0;
+    System.out.println("... Calculating sqrt of " + x + " starting with guess: " + guess);
+    return 1.0;
+  }
+
+
+  public static void main(String args[]) {
+    Math06 m = new Math06();
+
+    m.sqrt(36, 4.0);
+
+    m.sqrt(36);        // 01 make guess optional
+
+    m.sqrt(36.0);     // 02 send a float
+  }
+
+}

Java/Animal05.java

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+class Polygon {
+  int numSides;
+
+  public Polygon(int numSides) {
+    this.numSides = numSides;
+  }
+
+  public double getArea() {
+    return 2.0; // no idea how to calculate this!
+  }
+}
+
+// 01 -- add a class
+class Rectangle extends Polygon {
+//   // 02 add a constructor
+	public Rectangle() {
+	     super(4);
+	}
+//
+	double length;
+	double width;
+	public void setSides(double length, double width) {
+	this.length = length;
+	this.width = width;
+	}
+
+//   // // 03 overriding
+	 @Override // and change fn name to get error
+	 public double getArea() {
+		return this.length * this.width;
+	}
+ }
+
+
+public class Runner07 {
+  public static void main(String args[]) {
+    Polygon p = new Polygon(4);        // error because no default constructor
+    System.out.println("Area of poly: " + p.getArea());  // this does not make sense
+
+	Rectangle r = new Rectangle();    // also an error due to no default constructor
+	r.setSides(4, 4);
+	System.out.println("Area of rect: " + r.getArea());  // this does not make sense
+
+  }
+}

Java/Intro01.class

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+class Polygon {
+  int numSides;
+
+  public Polygon(int numSides) {
+    this.numSides = numSides;
+  }
+
+  // 01: add abstract, then make class abstract then don't instantiate 
+  public double getArea() {
+    return 2.0;     // no idea how to calculate this!
+  }
+}
+
+class Rectangle extends Polygon {
+
+  public Rectangle() {
+    super(4);
+  }
+
+  double length;
+  double width;
+  public void setSides(double length, double width) {
+    this.length = length;
+    this.width = width;
+  }
+
+  @Override
+  public double getArea() {
+    return this.length * this.width;
+  }
+}
+
+
+public class Runner08 {
+  public static void main(String args[]) {
+    Polygon p = new Polygon(3);
+    System.out.println("Area of poly: " + p.getArea());  // this does not make sense
+
+    Rectangle r = new Rectangle();
+    // Polygon r = new Rectangle();    // 02 -- parent class reference var, child object 
+
+    r.setSides(4, 4);
+    System.out.println("Area of rect: " + r.getArea());
+
+  }
+}

Java/Intro01.java

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+class Polygon {
+  int numSides;
+
+  public Polygon(int numSides) {
+    this.numSides = numSides;
+  }
+
+  // 01: add abstract, then make class abstract then don't instantiate 
+  public double getArea() {
+    return 2.0;     // no idea how to calculate this!
+  }
+}
+
+class Rectangle extends Polygon {
+
+  public Rectangle() {
+    super(4);
+  }
+
+  double length;
+  double width;
+  public void setSides(double length, double width) {
+    this.length = length;
+    this.width = width;
+  }
+
+  @Override
+  public double getArea() {
+    return this.length * this.width;
+  }
+}
+
+
+public class Runner08 {
+  public static void main(String args[]) {
+    Polygon p = new Polygon(3);
+    System.out.println("Area of poly: " + p.getArea());  // this does not make sense
+
+    Rectangle r = new Rectangle();
+    // Polygon r = new Rectangle();    // 02 -- parent class reference var, child object 
+
+    r.setSides(4, 4);
+    System.out.println("Area of rect: " + r.getArea());
+
+  }
+}

Java/Math06.java

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+interface Plugin {
+  // serves as a contract
+  public void draw();
+  public void save();
+
+}
+
+class TextEditorPlugin implements Plugin {
+  public void draw() {
+     System.out.println("Drawing text");
+   }
+  
+  public void save() {
+     System.out.println("Saved text");
+   }
+}
+
+class PDFViewerPlugin implements Plugin {
+   public void draw() {
+     System.out.println("Showing PDF");
+   }
+
+   public void save() {
+     System.out.println("Saved PDF annotations");
+   }
+ }
+
+
+public class Runner09 {
+  public static void main(String args[]) {
+    // assume this is your atom editor
+
+    Plugin p = new TextEditorPlugin();  // reference variable of interface can hold implementing class object
+    // Plugin p = new PDFViewerPlugin();
+
+    p.draw();
+    p.save();
+
+  }
+}

Java/PDFViewerPlugin.class

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+/*
+Download slf4j binary from: https://www.slf4j.org/download.html
+Extract to get jar files:
+ - slf4j-api-1.7.25.jar      (or whichever version they have)
+ - slf4j-simple-1.7.25.jar
+Copy them to your working_directory/lib/ folder
+Compile: javac -cp .:lib/slf4j-api-1.7.25.jar:lib/slf4j-simple-1.7.25.jar Runner10.java   (replace colon with semicolon on Windows)
+Execute: java -cp .:lib/slf4j-api-1.7.25.jar:lib/slf4j-simple-1.7.25.jar Runner10
+*/
+
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+
+
+
+public class Runner10 {
+
+
+  public static void main(String args[]) {
+    Logger logger = LoggerFactory.getLogger(Runner10.class);
+
+    logger.info("A message with the info level");
+    logger.warn("Warning level message ...");
+  }
+}

Java/Plugin.class

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+import java.util.Vector;    // import Vector class from java.util package
+
+public class Runner11 {
+
+  public void printVector(Vector v) {
+    for (int i = 0; i < v.size(); i++){
+      System.out.println(v.get(i));
+
+    }
+  }
+
+  public void intVectorTest() {
+    Vector vi = new Vector();
+    vi.add(4);
+    vi.add(5);
+    vi.add("something");
+
+    printVector(vi);
+    // System.out.println(vi);    // can also output directly
+
+  }
+
+  // public void stringVectorTest() {
+  //   Vector<String> vs = new Vector<String>();  // specify type of vector
+  //   vs.add("first");
+  //   vs.add("second");
+  //   vs.add("third");
+  //
+  //   System.out.println(vs);
+  //
+  // }
+
+  public static void main(String args[]) {
+    Runner11 r = new Runner11();
+    r.intVectorTest();
+
+    // r.stringVectorTest();
+
+    // comment out intVectorTest definition to get rid of warning
+  }
+}
+
+
+// add a CLI argument

Java/Polygon.class

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+public class Student03 {
+  static int num = 0;
+  int rollNo;
+
+  public static void main(String args[]) {
+
+    Student03 s1 = new Student03();
+    Student03 s2 = new Student03();
+
+    System.out.println("num: " + Student03.num);
+
+    Student03.num += 1;
+    System.out.println("num: " + Student03.num);
+
+    System.out.println("s1.num: " + s1.num);
+    System.out.println("s2.num: " + s2.num);
+
+    System.out.println("rollNo:" + s1.rollNo);
+
+
+  }
+}