Interface ConstantPoolBuilder

All Superinterfaces:
ConstantPool, Iterable<PoolEntry>
public sealed interface ConstantPoolBuilder extends ConstantPool
Builder for the constant pool of a class file. Provides read and write access to the constant pool that is being built. Writing is append-only (the index of new entries monotonically increase) and idempotent (entry-bearing methods will return an existing entry if there is a suitable one).

For class file building, an overload of ClassFile::build takes a ConstantPoolBuilder. For class file transformations via ClassFile::transformClass, the ClassFile.ConstantPoolSharingOption controls how the constant pool builder of the resulting class is created.

Alien Constant Pool Entries

In class file building and constant pool building, some constant pool entries supplied may be alien to this constant pool builder of the active class file builder. For example, classEntry(Utf8Entry) may be called with an alien UTF8 entry. Alien entries will be converted to a pool entry in this constant pool builder, reusing equivalent entries or adding new entries if there is none. As a result, all pool entries returned by entry-bearing methods in this constant pool builder belong to this constant pool.

Some ClassFileBuilder methods may have their outputs adjusted if they receive pool entries alien to their constant pools. For example, if an ldc_w instruction with an alien entry is written to a CodeBuilder, the CodeBuilder may emit a functionally equivalent ldc instruction instead, if the converted entry can be encoded in such an instruction.

To avoid the conversion of alien constant pool entries, such as for the accuracy of the generated class file, users can always supply constant pool entries obtained by calling the constant pool builder entry-bearing methods of the constant pools associated with the ClassFileBuilder. Otherwise, the conversions have no impact on the behaviors of the generated class files.

Since:
24
See Also: