Interface ConstantPool

All Superinterfaces:

Iterable<PoolEntry>

All Known Subinterfaces:

ClassReader, ConstantPoolBuilder

public sealed interface ConstantPool
extends Iterable<PoolEntry>
permits ClassReader, ConstantPoolBuilder

Provides read access to the constant pool and the bootstrap method table of a class file.

Index in the Constant Pool

The constant pool entries are accessed by index. A valid index is in the range of [1, size()). It is unusable if a LongEntry or DoubleEntry is at its previous index.

See Java Virtual Machine Specification:

4.4 The Constant Pool

Since:

24

See Also:

• BootstrapMethodsAttribute

Method Summary

Modifier and Type	Method	Description
int	bootstrapMethodCount()	Returns the number of entries in the bootstrap method table.
BootstrapMethodEntry	bootstrapMethodEntry(int index)	Returns the BootstrapMethodEntry at the specified index within the bootstrap method table.
PoolEntry	entryByIndex(int index)	Returns the entry at the specified index.
<T extends PoolEntry> T	entryByIndex(int index, Class<T> cls)	Returns the entry of a given type at the specified index.
default Iterator<PoolEntry>	iterator()	Returns an iterator over pool entries.
int	size()	Returns the exclusive upper bound of the valid indices of this constant pool.

Methods declared in interface Iterable

forEach, spliterator

Modifier and Type	Method	Description
default void	forEach(Consumer<? super PoolEntry> action)	Performs the given action for each element of the Iterable until all elements have been processed or the action throws an exception.
default Spliterator<PoolEntry>	spliterator()	Creates a Spliterator over the elements described by this Iterable.

Method Details

entryByIndex

PoolEntry entryByIndex(int index)

Returns the entry at the specified index.

API Note:

If only a particular type of entry is expected, use entryByIndex(int, Class).

Parameters:

index - the index within the pool of the desired entry

Returns:

the entry at the specified index

Throws:

ConstantPoolException - if the index is out of range of the constant pool, or is considered unusable

size

int size()

Returns the exclusive upper bound of the valid indices of this constant pool. The actual number of entries is lower because 0, size() are not valid, and a valid index may be unusable.

Returns:

the exclusive upper bound of the valid indices of this constant pool

See Also:

• Index in the Constant Pool

entryByIndex

<T extends PoolEntry> T entryByIndex(int index,
 Class<T> cls)

Returns the entry of a given type at the specified index.

Type Parameters:

T - the entry type

Parameters:

index - the index within the pool of the desired entry

cls - the entry type

Returns:

the entry of a given type at the specified index

Throws:

ConstantPoolException - if the index is out of range of the constant pool or considered unusable, or the entry is not of the given type

iterator

default Iterator<PoolEntry> iterator()

Returns an iterator over pool entries.

Specified by:

iterator in interface Iterable<PoolEntry>

API Note:

This skips any unusable index and is less error-prone than iterating by raw index. See Index in the Constant Pool.

Returns:

an iterator over pool entries

bootstrapMethodEntry

BootstrapMethodEntry bootstrapMethodEntry(int index)

Returns the BootstrapMethodEntry at the specified index within the bootstrap method table.

Parameters:

index - the index within the bootstrap method table of the desired entry

Returns:

the BootstrapMethodEntry at the specified index within the bootstrap method table

Throws:

ConstantPoolException - if the index is out of range of the bootstrap methods

bootstrapMethodCount

int bootstrapMethodCount()

Returns the number of entries in the bootstrap method table.

Returns:

the number of entries in the bootstrap method table