diff --git a/src/ArrayPractice.java b/src/ArrayPractice.java index bc58c83..4adf9d4 100644 --- a/src/ArrayPractice.java +++ b/src/ArrayPractice.java @@ -1,18 +1,33 @@ public class ArrayPractice { public static void main(String[] args) { // Create an array of Strings of size 4 + String [] words = new String[4]; // Set the value of the array at each index to be a different String // It's OK to do this one-by-one + words[0] = "Diamond"; + words[1] = "Ruby"; + words[2] = "Pearl"; + words[3] = "Emerald"; // Get the value of the array at index 2 + String valAtTwo = words[2]; // Get the length of the array + int wordsLength = words.length; // Iterate over the array using a traditional for loop and print out each item + for(int i = 0; i < words.length; i++) + { + System.out.println(words[i]); + } + System.out.println(); // Iterate over the array using a for-each loop and print out each item - + for(String word : words) + { + System.out.println(word); + } /* * Reminder! * diff --git a/src/ListPractice.java b/src/ListPractice.java index f4de8e7..c326fb1 100644 --- a/src/ListPractice.java +++ b/src/ListPractice.java @@ -1,28 +1,48 @@ +import java.util.ArrayList; +import java.util.List; +import java.util.*; + public class ListPractice { public static void main(String[] args) { // Create an empty ArrayList of Strings and assign it to a variable of type List + List wordList= new ArrayList<>(); // Add 3 elements to the list (OK to do one-by-one) + wordList.add("Hello"); + wordList.add("Beautiful"); + wordList.add("World"); // Print the element at index 1 + System.out.println(wordList.get(1)); + System.out.println(); // Replace the element at index 1 with a new value + wordList.set(1, "Hi"); + // (Do not insert a new value. The length of the list should not change) // Insert a new element at index 0 (the length of the list will change) + wordList.add(0,"Hola"); // Check whether the list contains a certain string - + wordList.contains("World"); // Iterate over the list using a traditional for-loop. // Print each index and value on a separate line - + for(int i = 0; i < wordList.size(); i++) + { + System.out.println("Index: " + i + " Value: "+ wordList.get(i)); + } + System.out.println(); // Sort the list using the Collections library - + Collections.sort(wordList); // Iterate over the list using a for-each loop // Print each value on a second line - + for(String word : wordList) + { + System.out.println("Value: " + word + " "); + } /* * Usage tip! * diff --git a/src/MapPractice.java b/src/MapPractice.java index 7ebfeac..0567888 100644 --- a/src/MapPractice.java +++ b/src/MapPractice.java @@ -1,29 +1,52 @@ - +import java.util.HashMap; +import java.util.List; +import java.util.Map; public class MapPractice { public static void main(String[] args) { // Create a HashMap with String keys and Integer values and // assign it to a variable of type Map + Map wordMap = new HashMap <>(); // Put 3 different key/value pairs in the Map // (it's OK to do this one-by-one) + wordMap.put("Glasgow", 1); + wordMap.put("Mexico City", 10); + wordMap.put("Madrid", 2); // Get the value associated with a given key in the Map + wordMap.get("Glasgow"); // Find the size (number of key/value pairs) of the Map + wordMap.size(); // Replace the value associated with a given key (the size of the Map shoukld not change) + wordMap.replace("Mexico City", 20); // Check whether the Map contains a given key + wordMap.containsKey("Madrid"); // Check whether the Map contains a given value + wordMap.containsValue(13); // Iterate over the keys of the Map, printing each key - + for(String key : wordMap.keySet()) + { + System.out.println(key); + } + System.out.println(); // Iterate over the values of the map, printing each value - + for(int value : wordMap.values()) + { + System.out.println(value); + } + System.out.println(); // Iterate over the entries in the map, printing each key and value - + for(String key : wordMap.keySet()) + { + System.out.println("Key: " + key + " Value: " + wordMap.get(key)); + } + /* * Usage tip! * diff --git a/src/NumberPractice.java b/src/NumberPractice.java index bbec2fe..de51c80 100644 --- a/src/NumberPractice.java +++ b/src/NumberPractice.java @@ -21,5 +21,18 @@ public static void main(String args[]) { * 7 / 3 = 2 when performing int division */ + double negFloat = -1.5; + int posInt = 1; + int remainder = posInt % 3; + if(remainder % 2 == 0) + { + System.out.println("even"); + } + else + { + System.out.println("odd"); + } + int intDivision = remainder / 5; + } } diff --git a/src/Person.java b/src/Person.java index 8ab3f95..dbd8ba2 100644 --- a/src/Person.java +++ b/src/Person.java @@ -6,14 +6,33 @@ public class Person { // Declare a public String instance variable for the name of the person // Declare a private int instance variable for the age of the person - + public String name; + private int age; // Create a constructor that takes the name and age of the person // and assigns it to the instance variables - + public Person(String pName, int pAge) + { + name = pName; + age = pAge; + } // Create a toString method that gives the name and age of the person + @Override + public String toString() + { + return "Name: " + name + " Age: " + age; + } + public String getName() + { + return name; + } + + public int getAge() + { + return age; + } // Implement the below public instance method "birthYear" // There should NOT be any print statement in this method. @@ -28,25 +47,35 @@ public class Person { * @return The year the person was born */ // (create the instance method here) - + public int birthYear(int currentYear) + { + return currentYear - age; + } public static void main(String[] args) { // Create an instance of Person + Person person1 = new Person("Ivy", 20); // Create another instance of Person with a different name and age and // assign it to a different variable + Person person2 = new Person("Kai", 17); // Print the first person + System.out.println(person1); // Print the second person + System.out.println(person2); // Get the name of the first person and store it in a local variable + String pName1 = person1.getName(); // Using the birthYear method, get the birth year of the first person // and store it in a local variable. Input the actual current year (e.g. 2025) // as the argument. + int pBirthYear1 = person1.birthYear(2025); // In a separate statement, print the local variable holding the birth year. + System.out.println(pBirthYear1); /** * Terminology! diff --git a/src/SetPractice.java b/src/SetPractice.java index d2fc1c9..bda5d2e 100644 --- a/src/SetPractice.java +++ b/src/SetPractice.java @@ -1,18 +1,30 @@ +import java.util.HashSet; +import java.util.*; + public class SetPractice { public static void main(String[] args) { // Create a HashSet of Strings and assign it to a variable of type Set + Set stringSet = new HashSet<>(); // Add 3 elements to the set // (It's OK to do it one-by-one) + stringSet.add("Sweet"); + stringSet.add("Salty"); + stringSet.add("Sour"); // Check whether the Set contains a given String + boolean hasSour = stringSet.contains("Sour"); // Remove an element from the Set + stringSet.remove("Sour"); // Get the size of the Set - + stringSet.size(); // Iterate over the elements of the Set, printing each one on a separate line - + for(String s : stringSet) + { + System.out.println(s); + } /* * Warning! * diff --git a/src/StringPractice.java b/src/StringPractice.java index 8d87617..9f70592 100644 --- a/src/StringPractice.java +++ b/src/StringPractice.java @@ -1,25 +1,47 @@ +import java.util.ArrayList; +import java.util.List; + public class StringPractice { public static void main(String[] args) { // Create a string with at least 5 characters and assign it to a variable + String fiveChar = "Sprinkles"; // Find the length of the string + fiveChar.length(); // Concatenate (add) two strings together and reassign the result + fiveChar = fiveChar + "Frosting"; // Find the value of the character at index 3 + char charAtThree = fiveChar.charAt(3); + //System.out.println(charAtThree); // Check whether the string contains a given substring (i.e. does the string have "abc" in it?) + boolean hasRink = fiveChar.contains("rink"); + //System.out.println(hasRink); // Iterate over the characters of the string, printing each one on a separate line - + for(int i = 0; i < fiveChar.length(); i++) + { + System.out.println(fiveChar.charAt(i)); + } + System.out.println(); // Create an ArrayList of Strings and assign it to a variable + List wordList = new ArrayList<>(); // Add multiple strings to the List (OK to do one-by-one) + wordList.add("Cake"); + wordList.add("Berries"); + wordList.add("Candles"); // Join all of the strings in the list together into a single string separated by commas // Use a built-in method to achieve this instead of using a loop + String combinedList = wordList.get(0) + ", " + wordList.get(1) + ", " + wordList.get(2); + //System.out.println(combinedList); // Check whether two strings are equal + boolean isEqual = combinedList.equals(fiveChar); + //System.out.println(isEqual); /* * Reminder!