26 lines
813 B
Java
26 lines
813 B
Java
// collections/Statistics.java
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// (c)2021 MindView LLC: see Copyright.txt
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// We make no guarantees that this code is fit for any purpose.
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// Visit http://OnJava8.com for more book information.
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// Simple demonstration of HashMap
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import java.util.*;
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public class Statistics {
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public static void main(String[] args) {
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Random rand = new Random(47);
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Map<Integer, Integer> m = new HashMap<>();
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for(int i = 0; i < 10000; i++) {
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// Produce a number between 0 and 20:
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int r = rand.nextInt(20);
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Integer freq = m.get(r); // [1]
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m.put(r, freq == null ? 1 : freq + 1);
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}
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System.out.println(m);
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}
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}
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/* Output:
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{0=481, 1=502, 2=489, 3=508, 4=481, 5=503, 6=519,
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7=471, 8=468, 9=549, 10=513, 11=531, 12=521, 13=506,
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14=477, 15=497, 16=533, 17=509, 18=478, 19=464}
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*/
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