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July 16, 2018 12:23
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Java Iterator Performance - HashSet/TreeSet
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import java.util.*; | |
public class Main { | |
static class Point implements Comparable<Point> { | |
long x; | |
long y; | |
public Point(long x, long y) { | |
this.x = x; | |
this.y = y; | |
} | |
@Override | |
public int compareTo(Point o) { | |
if (x != o.x) | |
return Long.compare(x, o.x); | |
return Long.compare(y, o.y); | |
} | |
public boolean equals(Object o) { | |
if (o instanceof Point) | |
return this.compareTo((Point) o) == 0; | |
return false; | |
} | |
@Override | |
public int hashCode() { | |
return (int) (x ^ y); | |
} | |
} | |
static long iterator(Set<Point> A, Set<Point> B) { | |
long startTime = System.currentTimeMillis(); | |
long sum = 0; | |
for (int it = 0; it < 10; it++) { | |
for (Point p : A) { | |
for (Point q : B) | |
sum += p.x * q.y; | |
} | |
} | |
long estimatedTime = System.currentTimeMillis() - startTime; | |
System.out.printf("%d %X\n", estimatedTime, sum); | |
return estimatedTime; | |
} | |
public static void main(String[] args) { | |
HashSet<Point> A, B; | |
TreeSet<Point> C, D; | |
Random rand = new Random(); | |
A = new HashSet<>(); | |
B = new HashSet<>(); | |
C = new TreeSet<>(); | |
D = new TreeSet<>(); | |
for (int i = 0; i < 500000; i++) { | |
long x = rand.nextLong(); | |
long y = rand.nextLong(); | |
Point p = new Point(x, y); | |
A.add(p); | |
C.add(p); | |
} | |
for (int i = 0; i < 1; i++) { | |
long x = rand.nextLong(); | |
long y = rand.nextLong(); | |
Point p = new Point(x, y); | |
B.add(p); | |
D.add(p); | |
} | |
for (int i = 0; i < 10; i++) { | |
System.out.println("HashSet"); | |
iterator(A, B); | |
System.out.println("TreeSet"); | |
iterator(C, D); | |
} | |
} | |
} |
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