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Semester 2/Programming 2/Assessment 3 Revision/Parameter Passing WS2.md

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+# Exercise 1
+
+```java 
+class Param1
+{
+	public int y;
+	// default constructor here
+	public void method1(int x)
+	{
+		y = 2*x;
+	}
+	
+	public int getY()
+	{
+		return y;
+	}
+}
+```
+
+Param1 q1 = new Param1();
+int y = 25; //Local Variable
+q1.y = 100; //Field Variable
+q1.method1(y); //method1(25) -> this.y = 50
+System.out.println(y);
+System.out.println(q1.getY());
+
+` y = 25 `
+` this.y = 50 `
+
+```java
+class Param2
+{
+	public int y;
+	// default constructor here
+	public void method1(int x)
+	{
+		y = 2*x;
+	}
+	
+	public int method2(int w)
+	{
+		return 3*w;
+	}
+}
+```
+
+Param2 q2 = new Param2();
+int y = 25; //Local Variable
+q2.y = 100; //Field Variable
+q2.method1(y); //method1(25) -> this.y = 50
+System.out.println(y);
+System.out.println(q2.y);
+System.out.println(q2.method2(y));
+
+`y = 25`
+`this.y = 50`
+`method2(y) = 3*y = 3*25 = 75`
+
+```java
+class Param3
+{
+	public int y;
+	// default constructor here
+	public void method1(int y)
+	{
+		y = y*3; // Local Variable
+	}
+	public int getY()
+	{
+		return y;
+	}
+}
+```
+
+Param3 q3 = new Param3();
+q3.y = 100; //Field Variable
+q3.method1(25); //Local y = 25x3 = 75
+System.out.println(q3.getY());
+
+`y = 100`
+
+```java
+class Param4
+{
+	private int w;
+	public Param4()
+	{
+		w = 5;
+	}
+	public void method1(int w)
+	{
+		this.w = w*3;
+	}
+	public int getW()
+	{
+		return w;
+	}
+}
+```
+
+Param4 q4 = new Param4();
+System.out.println(q4.getW());
+q4.method1(25);
+System.out.println(q4.getW())
+
+` w = 5 `
+` this.w = 15 `
+` w = 15 `
+
+# Exercise 2
+
+```java
+class Param5
+{
+	private int a, b;
+	public Param5()
+	{
+		b = 2;
+	}
+	public void method1(int b)
+	{
+		a = this.b + 5;
+		System.out.println(a);
+		a = method2(b);
+		System.out.println(a);
+		System.out.println(this.b);
+	}
+	public int method2(int a)
+	{
+		b = 2 + a;
+		return this.a + b;
+	}
+}
+```
+
+Param5 q5 = new Param5();
+q5.method1(3);
+
+Field Variable b = 2
+Local Variable b = 3
+Field a = 2 + 5 = 7
+output 7
+a = method2(3)
+	Field b = 2 + 3  = 5
+	return 7 + 5 = 12
+Field a = 12
+output 12
+output 5
+
+```java
+public void arrayMethod(int[] stats) //B
+{
+	for (int k = 0; k < stats.length; k+=2)
+		stats[k] = k; //C
+}
+```
+
+int [] numbers = {5, 10, 15, 20}; //A
+arrayMethod(numbers);
+
+Draw four state-of-memory diagrams to indicate the situation immediately after A has been executed, on starting execution of the method at B, immediately before returning from the method i.e. at C and after the method has been fully executed i.e. in the order in which the statements above are executed.
+
+| numbers | -> | 5, 10, 15, 20 |
+| numbers | -> | stats |
+| stats | -> | 0, 10, 2, 20 |
+| numbers | -> | 0, 10, 2, 20 |
+