Below is the syntax highlighted version of Transaction.java.
/****************************************************************************** * Compilation: javac Transaction.java * Execution: java Transaction * Dependencies: StdOut.java * * Data type for commercial transactions. * ******************************************************************************/ package edu.princeton.cs.algs4; import java.util.Arrays; import java.util.Comparator; /** * The {@code Transaction} class is an immutable data type to encapsulate a * commercial transaction with a customer name, date, and amount. * <p> * For additional documentation, * see <a href="https://algs4.cs.princeton.edu/12oop">Section 1.2</a> of * <i>Algorithms, 4th Edition</i> by Robert Sedgewick and Kevin Wayne. * * @author Robert Sedgewick * @author Kevin Wayne */ public class Transaction implements Comparable<Transaction> { private final String who; // customer private final Date when; // date private final double amount; // amount /** * Initializes a new transaction from the given arguments. * * @param who the person involved in this transaction * @param when the date of this transaction * @param amount the amount of this transaction * @throws IllegalArgumentException if {@code amount} * is {@code Double.NaN}, {@code Double.POSITIVE_INFINITY}, * or {@code Double.NEGATIVE_INFINITY} */ public Transaction(String who, Date when, double amount) { if (Double.isNaN(amount) || Double.isInfinite(amount)) throw new IllegalArgumentException("Amount cannot be NaN or infinite"); this.who = who; this.when = when; this.amount = amount; } /** * Initializes a new transaction by parsing a string of the form NAME DATE AMOUNT. * * @param transaction the string to parse * @throws IllegalArgumentException if {@code amount} * is {@code Double.NaN}, {@code Double.POSITIVE_INFINITY}, * or {@code Double.NEGATIVE_INFINITY} */ public Transaction(String transaction) { String[] a = transaction.split("\\s+"); who = a[0]; when = new Date(a[1]); amount = Double.parseDouble(a[2]); if (Double.isNaN(amount) || Double.isInfinite(amount)) throw new IllegalArgumentException("Amount cannot be NaN or infinite"); } /** * Returns the name of the customer involved in this transaction. * * @return the name of the customer involved in this transaction */ public String who() { return who; } /** * Returns the date of this transaction. * * @return the date of this transaction */ public Date when() { return when; } /** * Returns the amount of this transaction. * * @return the amount of this transaction */ public double amount() { return amount; } /** * Returns a string representation of this transaction. * * @return a string representation of this transaction */ @Override public String toString() { return String.format("%-10s %10s %8.2f", who, when, amount); } /** * Compares two transactions by amount. * * @param that the other transaction * @return { a negative integer, zero, a positive integer}, depending * on whether the amount of this transaction is { less than, * equal to, or greater than } the amount of that transaction */ public int compareTo(Transaction that) { return Double.compare(this.amount, that.amount); } /** * Compares this transaction to the specified object. * * @param other the other transaction * @return true if this transaction is equal to {@code other}; false otherwise */ @Override public boolean equals(Object other) { if (other == this) return true; if (other == null) return false; if (other.getClass() != this.getClass()) return false; Transaction that = (Transaction) other; return (this.amount == that.amount) && (this.who.equals(that.who)) && (this.when.equals(that.when)); } /** * Returns a hash code for this transaction. * * @return a hash code for this transaction */ public int hashCode() { int hash = 1; hash = 31*hash + who.hashCode(); hash = 31*hash + when.hashCode(); hash = 31*hash + ((Double) amount).hashCode(); return hash; // return Objects.hash(who, when, amount); } /** * Compares two transactions by customer name. */ public static class WhoOrder implements Comparator<Transaction> { @Override public int compare(Transaction v, Transaction w) { return v.who.compareTo(w.who); } } /** * Compares two transactions by date. */ public static class WhenOrder implements Comparator<Transaction> { @Override public int compare(Transaction v, Transaction w) { return v.when.compareTo(w.when); } } /** * Compares two transactions by amount. */ public static class HowMuchOrder implements Comparator<Transaction> { @Override public int compare(Transaction v, Transaction w) { return Double.compare(v.amount, w.amount); } } /** * Unit tests the {@code Transaction} data type. * * @param args the command-line arguments */ public static void main(String[] args) { Transaction[] a = new Transaction[4]; a[0] = new Transaction("Turing 6/17/1990 644.08"); a[1] = new Transaction("Tarjan 3/26/2002 4121.85"); a[2] = new Transaction("Knuth 6/14/1999 288.34"); a[3] = new Transaction("Dijkstra 8/22/2007 2678.40"); StdOut.println("Unsorted"); for (int i = 0; i < a.length; i++) StdOut.println(a[i]); StdOut.println(); StdOut.println("Sort by date"); Arrays.sort(a, new Transaction.WhenOrder()); for (int i = 0; i < a.length; i++) StdOut.println(a[i]); StdOut.println(); StdOut.println("Sort by customer"); Arrays.sort(a, new Transaction.WhoOrder()); for (int i = 0; i < a.length; i++) StdOut.println(a[i]); StdOut.println(); StdOut.println("Sort by amount"); Arrays.sort(a, new Transaction.HowMuchOrder()); for (int i = 0; i < a.length; i++) StdOut.println(a[i]); StdOut.println(); } } /****************************************************************************** * Copyright 2002-2022, Robert Sedgewick and Kevin Wayne. * * This file is part of algs4.jar, which accompanies the textbook * * Algorithms, 4th edition by Robert Sedgewick and Kevin Wayne, * Addison-Wesley Professional, 2011, ISBN 0-321-57351-X. * http://algs4.cs.princeton.edu * * * algs4.jar is free software: you can redistribute it and/or modify * it under the terms of the GNU General Public License as published by * the Free Software Foundation, either version 3 of the License, or * (at your option) any later version. * * algs4.jar is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the * GNU General Public License for more details. * * You should have received a copy of the GNU General Public License * along with algs4.jar. If not, see http://www.gnu.org/licenses. ******************************************************************************/