| # Collections Framework API Change Summary

This page summarizes the differences between the 1.2 and 1.3 releases of the Collections Framework, along with a brief rationale for each change.

### Convenience Implementations

- Added singletonList and singletonMap. Previously, there was a convenience implementation for singleton Set, but no corresponding implementation for List and Map.

- Added EMPTY_MAP. Previously, there were constants for the empty Set and List, but no corresponding constant for Map.

### Special-purpose Implementation

- Added Map constuctor for WeakHashMap. The Map interface dictates that most Map implementations should have a "copy constructor" that takes a Map argument. WeakHashMap lacked such a constructor in the 1.2 release.

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