import javax.swing.JOptionPane; import java.util.ArrayList; import java.util.Scanner; public class ArrayCode { public void arrayExample() { String name1 = "Josh"; String name2 = "Irene"; String name3 = "Ethan"; // set up an array String[] names = new String[15000]; names[0] = "Josh"; names[1] = "Irene"; names[2] = "Ethan"; int[] ages = new int[20]; ages[0] = 17; ages[1] = 16; ages[2] = 17; int[] primes = {2, 3, 5, 7, 11, 13}; JOptionPane.showMessageDialog(null, primes[3]); } public void arrayList2() { String[] names = {"Michael", "CJ", "Sahil", "Sophia", "Bill"}; String[] entrees = {"mac & cheese", "cheeseburger", "pasta", "salmon", "shepherd's pie"}; int k; String msg = ""; for (k = 0; k < 5; k++) { msg += names[k] + " - " + entrees[k] + "\n"; } JOptionPane.showMessageDialog(null, msg); } public void array3() { String[] days = {"Sun","Mon","Tues","Wed","Thurs","Fri","Sat"}; // for-each loop for (String day : days) { System.out.println("day: " + day); } } public void array4() { // the length property of an array tells you how many slots are // available in the array, not how many slots are filled // how to deal with that? double[] nums = new double[5]; JOptionPane.showMessageDialog(null, nums.length); int numFilled = 0; nums[0] = 3.14; numFilled++; nums[1] = -88.7; numFilled++; nums[2] = 11.1; numFilled++; nums[3] = 0; numFilled++; for (int k = 0; k < numFilled; k++) { System.out.println(nums[k]); } Scanner in = new Scanner(System.in); for (int k = 0; k < 2; k++) { System.out.println("Give me a number"); double number = in.nextDouble(); if (numFilled < nums.length) { nums[numFilled] = number; numFilled++; System.out.println("Number added"); } else { System.out.println("No room for another number in the array."); } } } public void TwoDArray() { // box[row][column] String[][] box = new String[4][4]; box[1][1] = "X"; box[1][2] = "O"; box[1][3] = " "; box[2][1] = " "; box[2][2] = " "; box[2][3] = "O"; box[3][1] = "X"; box[3][2] = " "; box[3][3] = " "; for (int row = 1; row <= 3; row++) { for (int col = 1; col <= 3; col++) { System.out.print(box[row][col]); } System.out.println(); } } public void ArrayListExample() { ArrayList a = new ArrayList(); a.add("Ronan"); a.add("Ling"); a.add("Jayna"); System.out.println("a: " + a); a.add(1, "Irene Lin"); System.out.println("a: " + a); a.set(1, "Royal Thomas"); System.out.println("a: " + a); a.remove(1); System.out.println("a: " + a); a.remove("Ronan Gray"); System.out.println("a: " + a); System.out.println("size of a: " + a.size()); System.out.println("what is at position 0? " + a.get(0)); } public void ArrayListExample2() { // an ArrayList can only store objects, not primitives // no ints, doubles, booleans, chars // there are Integer, Double & Boolean classes // they are called "Wrapper classes" ArrayList numbers = new ArrayList(); numbers.add(3.1415926); numbers.add(-11.111); numbers.add(75.35634); System.out.println("numbers: " + numbers); } public static void main(String[] args) { ArrayCode ac = new ArrayCode(); ac.TwoDArray(); } }