CS111 Lab 1a:

Java Basics - Review and Practice

Part I: Methods

1. 
                   public static void main(String[] args ){
                       int x = 1, y = 2, z = 4;
                       System.out.print( "x = " +  x +  "y = " +  y + "z = " +  z);
                       
                       z = p(x,y);
                       System.out.print( "x = " +  x +  "y = " +  y + "z = " +  z);
                   }
     
                   public static int p (int x, int a ){
                       x = 7;
                       return a * 2 + x;
                   }
               

   
   
   

2. 
                   public static void main(String[] args ){
                       int x = 2, y = 3, z = 0;
                       System.out.print( "x = " +  x +  "y = " +  y + "z = " +  z);
                       
                       z = p(y,x);
                       System.out.print( "x = " +  x +  "y = " +  y + "z = " +  z);
                   }
     
                   public static int p (int z, int y ){
                       int x = z;
                       return y * 2 + z * 3 + x;
                   }
               

   
   
   

3. 
                   public static void main(String[] args ){
                       int x = 2, y = 3, z = 0;
                       x = p(x,y);
                       System.out.print( "x = " +  x +  "y = " +  y + "z = " +  z);
                       y = p(x,y);
                       System.out.print( "x = " +  x +  "y = " +  y + "z = " +  z);
                   }
     
                   public static int p (int x, int z ){
                       int y = z;
                       return x - z;
                   }
               

   
   
   

4. 
                   public static void main(String[] args ){
                       int x = 2, y = 3;
                       x = p(x,y);
                       x = p(y,x);
                       x = p(x,y);
                       System.out.print( "x = " +  x +  "y = " +  y);
                   }
           
                   public static int p (int y, int x){
                       return 2 * x + y;
                   }
               

   
   
   

5. 
                   public static void main(String[] args ){
                       int x = 2, y = 3, z = 0;
                       funcA (x, z);
                       System.out.print("INSIDE MAIN");
                       System.out.print( "x = " +  x +  "y = " +  y + "z = " +  z);
                   }
   
                   public static void funcA (int x, int y){
                       int z = x;
                       System.out.print("INSIDE DISPLAY");
                       System.out.print( "x = " +  x +  "y = " +  y + "z = " +  z);
                   }
               

   
   
   
6. The Farmer in the Dell is a children's song that most people have sung at one time or another. Write an efficient Java program that displays the lyrics of entire song.

The farmer in the dell The farmer in the dell Hi-ho, the derro-o The farmer in the dell The farmer takes a wife The farmer takes a wife Hi-ho, the derro-o The farmer takes a wife The wife takes a child The wife takes a child Hi-ho, the derro-o The wife takes a child The child takes a nurse The child takes a nurse Hi-ho, the derro-o The child takes a nurse The nurse takes a cow The nurse takes a cow Hi-ho, the derro-o The nurse takes a cow The cow takes a dog The cow takes a dog Hi-ho, the derro-o The cow takes a dog The dog takes a cat The dog takes a cat Hi-ho, the derro-o The dog takes a cat The cat takes a rat The cat takes a rat Hi-ho, the derro-o The cat takes a rat The rat takes the cheese The rat takes the cheese Hi-ho, the derro-o The rat takes the cheese The cheese stands alone The cheese stands alone Hi-ho, the derro-o The cheese stands alone

PART II: Arrays

1. What does the array nums contain after executing the following instructions?

   
                   int [] nums = {1, 2, 3, 4, 5, 6, 7, 9, 10, 11, 12};
                   nums[0] = nums[10 - 1];
                   nums[10 - 3] = 7;
               

   
   
   
2. What does the array nums contain after executing the following instructions?

   
                   int [] nums = {5, 10, 15, 20, 25, 30, 35};
                   int i = 4;
                   nums[i] = nums[i + 1];
               

   
   
   
3. What does the array nums contain after executing the following segment of code?

   
                   int [] nums = {2, 3, 5, 1, 8, 4, 9, -3, 6, 3};
                   
                   for (int i = 0; i < nums.length; i++){
                       nums[i] = nums[i] + 1;
                   }
               

   
   
   
4. What does the array nums contain after executing the following segment of code?

   
                   int [] nums = {10, 9, 8, 7, 6, 5, 4, 3, 2, 1, 0};
                   
                   for (int i = 0; i < nums.length - 2; i++){
                       nums[i] = nums[i + 1];
                   }
               

   
   
   
5. What output is produced after executing the following segment of code?
   NOTE: Arrays.toString(arr) is an easy way to display the contents of an integer array.

   				public static void main(String[] args) {
   					int[] arr = { 1, 2, 3 };
   					System.out.println(Arrays.toString(arr));
   					arr = func(arr);
   					System.out.println(Arrays.toString(arr));
   				}
   
   				public static int [] func(int[] arr) {
   					int [] brr = new int [arr.length*2];
   					int j = 0;
   					for (int i = 0; i < arr.length; i++){
   						brr[j] = arr[i];
   						j++;
   						brr[j] = arr[i];
   						j++;
   					}
   					return brr;
   				}
               

   
   
   

Part III: Strings

1. Write a method, noVowels(), that receives a String, str and removes all the vowels.
   
   Example:
   
   • noVowels("These fries are cold!") - "Ths frs r cld!"
   • noVowels("What time is it?") - Wht tm s t?
   
   
   
   

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2. Write a method, shuffle(), that receives a String, str and returns it shuffled.
   
   Example:
   
   • shuffle("banana") returns "anaanb"
   • shuffle("apple") returns "plpea"
   
   
   Use the Fisher-Yates (Knuth) Shuffle algorithm
   Implementation Tips:
   (a) Convert to Array: Use word.toCharArray() to get a mutable character array.
   (b) Iterate and Swap: Loop through the array visiting each character.
   (c) Random Index: For each character at position i, pick a random index in the word.
   (d) Swap: Exchange the characters at index i with the random. Use a temporary variable.
   
   
   
   
   

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3. Write a method, countCo_e(), that receives a String, str and counts and returns the number of times that the string "code" appears anywhere in the given string, except we'll accept any letter for the 'd'. This means we will count "cope", "coke", "come", "core", etc.
   
   Example:
   
   • countCode("aaacodebbb") returns 1
   • countCode("cokexxcode") returns 2
   • countCode("conexxcope") returns 2
   
   
   
   

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