forked from teddyzhang1976/ThinkInJava4thSampleCode
-
Notifications
You must be signed in to change notification settings - Fork 0
Expand file tree
/
Copy pathCanonicalMapping.java
More file actions
47 lines (43 loc) · 1.25 KB
/
Copy pathCanonicalMapping.java
File metadata and controls
47 lines (43 loc) · 1.25 KB
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
//: containers/CanonicalMapping.java
package containers; /* Added by Eclipse.py */
// Demonstrates WeakHashMap.
import java.util.*;
class Element {
private String ident;
public Element(String id) { ident = id; }
public String toString() { return ident; }
public int hashCode() { return ident.hashCode(); }
public boolean equals(Object r) {
return r instanceof Element &&
ident.equals(((Element)r).ident);
}
protected void finalize() {
System.out.println("Finalizing " +
getClass().getSimpleName() + " " + ident);
}
}
class Key extends Element {
public Key(String id) { super(id); }
}
class Value extends Element {
public Value(String id) { super(id); }
}
public class CanonicalMapping {
public static void main(String[] args) {
int size = 1000;
// Or, choose size via the command line:
if(args.length > 0)
size = new Integer(args[0]);
Key[] keys = new Key[size];
WeakHashMap<Key,Value> map =
new WeakHashMap<Key,Value>();
for(int i = 0; i < size; i++) {
Key k = new Key(Integer.toString(i));
Value v = new Value(Integer.toString(i));
if(i % 3 == 0)
keys[i] = k; // Save as "real" references
map.put(k, v);
}
System.gc();
}
} /* (Execute to see output) *///:~