good catch scott,
marcf
|-----Original Message-----
|From: [EMAIL PROTECTED]
|[mailto:[EMAIL PROTECTED]]On Behalf Of Scott
|M Stark
|Sent: Tuesday, July 10, 2001 2:32 PM
|To: [EMAIL PROTECTED]
|Subject: [JBoss-dev] Fool proof? I think not.
|
|
|// TestPK.java
|class AccountPK implements java.io.Serializable
|{
| private int _hashCode = Integer.MIN_VALUE;
| public java.lang.String id;
|
| public AccountPK(java.lang.String id)
| {
| this.id = id;
| }
| public int hashCode()
| {
| if (_hashCode == Integer.MIN_VALUE)
| {
| _hashCode += this.id.hashCode();
| }
| return _hashCode;
| }
| public boolean equals(Object obj)
| {
| AccountPK pk = (AccountPK)obj;
| boolean eq = true;
| eq = eq && this.id.equals(pk.id);
| return eq;
| }
|}
|
|public class TestPK
|{
| public static void main (String args[])
| {
| AccountPK key1 = new AccountPK("key1");
| AccountPK key2 = new AccountPK("key1");
| CacheKey key3 = new CacheKey(key1);
| CacheKey key4 = new CacheKey(key2);
| if( key3.hashCode() != key4.hashCode() )
| System.out.println("key3, key4 hashCode test failed");
| if( key3.equals(key4) == false )
| System.out.println("key3, key4 equals test failed");
|
| AccountPK key11 = new AccountPK("key1");
| AccountPK key21 = new AccountPK("key1");
| key21.hashCode(); // Cause key21._hashCode value to update
| CacheKey key31 = new CacheKey(key11);
| CacheKey key41 = new CacheKey(key21);
| if( key31.hashCode() != key41.hashCode() )
| System.out.println("key31, key41 hashCode test failed");
| if( key31.equals(key41) == false )
| System.out.println("key31, key41 equals test failed");
| }
|
|}
|
|Produces:
|
|key31, key41 hashCode test failed
|key31, key41 equals test failed
|
|Why? Because Serialization includes the private state of the
|object. This is
|a perfectly valid PK which is not handled correctly by CacheKey. If the
|_hashCode value is marked as transient all works. The assumption being
|made by CacheKey is that the only ivars in the PK are its fields
|that define
|its identity.
|
|
|
|
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