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# Enhancements to Pack200

- Enhancements in Java SE 8
- Enhancements in Java SE 6
- Enhancements in Java SE 5.0
- Enhancements in Java SE 1.4
- Previous Enhancements

## Enhancements in Java SE 8

### Pack200 Support for Constant Pool Entries and New Bytecodes Introduced by JSR 292

In Java SE 8, the Java class file format has been updated, in part, because of JSR 292: Supporting Dynamically Typed Languages on the Java Platform. (See also Java Virtual Machine Support for Non-Java Languages.)

Consequently, the Pack200 engine has been updated accordingly to ensure that Java SE 8 class files are compressed effectively. In particular, the Pack200 engine now recognizes constant pool entries and new bytecodes introduced by JSR 292. As a result, compressed files created with this version of the pack200 tool will not be compatible with older versions of the unpack200 tool. See Compression Formats for Network Development.

## Enhancements in Java SE 6

No current changes to report.

## Enhancements in Java SE 5.0

No current changes to report.

## Enhancements in Java SE 1.4

No current changes to report.

## Previous Enhancements

No current changes to report.

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