import edu.princeton.cs.introcs.StdOut; import edu.princeton.cs.introcs.StdRandom; /************************************************************************* * Compilation: javac Counter.java * Execution: java Counter N T * Dependencies: StdRandom.java StdOut.java * * A mutable data type for an integer counter. * * The test clients create N counters and performs T increment * operations on random counters. * * % java Counter 6 600000 * 0: 99870 * 1: 99948 * 2: 99738 * 3: 100283 * 4: 100185 * 5: 99976 * *************************************************************************/ /** * The 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; // 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 count. */ public int tally() { return count; } /** * Returns a string representation of this counter */ @Override public String toString() { return count + " " + name; } /** * Compares this counter to that counter. */ 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 T; creates N counters; * increments T counters at random; and prints results. */ public static void main(String[] args) { int N = Integer.parseInt(args[0]); int T = 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 T counters at random for (int t = 0; t < T; t++) { hits[StdRandom.uniform(N)].increment(); } // print results for (int i = 0; i < N; i++) { StdOut.println(hits[i]); } } }