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Java语言中的集合/SetTest.java

+import java.util.*;
+
+/**
+ * This program uses a set to print all unique words in System.in.
+ *
+ * @author Cay Horstmann
+ * @version 1.10 2003-08-02
+ */
+
+public class SetTest {
+    public static void main(String[] args) {
+        Set<String> words = new HashSet<>(); // HashSet implements Set
+        long totalTime = 0;
+
+        Scanner in = new Scanner(System.in);
+        while (in.hasNext()) {
+            String word = in.next();
+            long callTime = System.currentTimeMillis();
+            words.add(word);
+            callTime = System.currentTimeMillis() - callTime;
+            totalTime += callTime;
+        }
+
+        Iterator<String> iter = words.iterator();
+        for (int i = 1; i <= 20 && iter.hasNext(); i++)
+            System.out.println(iter.next());
+        System.out.println(". . .");
+        System.out.println(words.size() + " distinct words. " + totalTime + " milliseconds.");
+    }
+}