edu.princeton.cs.algs4.Counter Maven / Gradle / Ivy
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/******************************************************************************
* Compilation: javac Counter.java
* Execution: java Counter n trials
* Dependencies: StdRandom.java StdOut.java
*
* A mutable data type for an integer counter.
*
* The test clients create n counters and performs trials increment
* operations on random counters.
*
* java Counter 6 600000
* 100140 counter0
* 100273 counter1
* 99848 counter2
* 100129 counter3
* 99973 counter4
* 99637 counter5
*
******************************************************************************/
package edu.princeton.cs.algs4;
/**
* The {@code Counter} class is a mutable data type to encapsulate a counter.
*
* For additional documentation,
* see Section 1.2 of
* Algorithms, 4th Edition by Robert Sedgewick and Kevin Wayne.
*
* @author Robert Sedgewick
* @author Kevin Wayne
*/
public class Counter implements Comparable {
private final String name; // counter name
private int count = 0; // current value
/**
* Initializes a new counter starting at 0, with the given id.
*
* @param id the name of the counter
*/
public Counter(String id) {
name = id;
}
/**
* Increments the counter by 1.
*/
public void increment() {
count++;
}
/**
* Returns the current value of this counter.
*
* @return the current value of this counter
*/
public int tally() {
return count;
}
/**
* Returns a string representation of this counter.
*
* @return a string representation of this counter
*/
public String toString() {
return count + " " + name;
}
/**
* Compares this counter to the specified counter.
*
* @param that the other counter
* @return {@code 0} if the value of this counter equals
* the value of that counter; a negative integer if
* the value of this counter is less than the value of
* that counter; and a positive integer if the value
* of this counter is greater than the value of that
* counter
*/
@Override
public int compareTo(Counter that) {
if (this.count < that.count) return -1;
else if (this.count > that.count) return +1;
else return 0;
}
/**
* Reads two command-line integers n and trials; creates n counters;
* increments trials counters at random; and prints results.
*
* @param args the command-line arguments
*/
public static void main(String[] args) {
int n = Integer.parseInt(args[0]);
int trials = Integer.parseInt(args[1]);
// create n counters
Counter[] hits = new Counter[n];
for (int i = 0; i < n; i++) {
hits[i] = new Counter("counter" + i);
}
// increment trials counters at random
for (int t = 0; t < trials; t++) {
hits[StdRandom.uniform(n)].increment();
}
// print results
for (int i = 0; i < n; i++) {
StdOut.println(hits[i]);
}
}
}
/******************************************************************************
* Copyright 2002-2018, 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.
******************************************************************************/