BufferIterator (Starjava ARRAY API)

java.lang.Object
- uk.ac.starlink.array.BufferIterator

All Implemented Interfaces:

java.util.Iterator
```
public class BufferIterator
extends java.lang.Object
implements java.util.Iterator
```
Provides buffers for convenient stepping through an array. At each step a primitive buffer of a given type of just the right size to match the current chunk is returned. This class is provided as a convenience for applications code which wishes to iterate through an array in sections, using a buffer of the size matching the section at each step.
This class provides a thin convenience wrapper around ChunkStepper, which is itself a simple class which steps from zero to a given limit in chunks. The only additional functionality provided by a BufferIterator is that it will ensure a suitable primitive buffer is available at each step, and (since the next method actually returns something, namely the buffer), it implements the Iterator interface which ChunkStepper does not.
A typical use of BufferIterator is as follows:
```
     ArrayAccess acc = ndarray.getAccess();
     for ( BufferIterator bufIt = new BufferIterator( npix, Type.DOUBLE );
           bufIt.hasNext(); ) {
         double[] buf = (double[]) bIt.next();
         acc.read( buf, 0, buf.length );
         doStuff( buf );
     }
 
```
Author:

Mark Taylor (Starlink)

See Also:

ChunkStepper

Constructor Summary

Constructors
Constructor and Description
`BufferIterator(long length)` Create a new `BufferIterator` with a default chunk size.
`BufferIterator(long length, Type type, int chunkSize)` Create a new `BufferIterator` with a given chunk size.

Method Summary

All Methods Instance Methods Concrete Methods
Modifier and Type	Method and Description
`long`	`getBase()` The offset of the base of the chunk most recently returned by `next`.
`boolean`	`hasNext()` See if iteration has finished.
`java.lang.Object`	`next()` Returns a primitive buffer of this object's type, with a length matching that of this chunk.
`void`	`remove()` Remove functionality is not implemented by this class.

Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Methods inherited from interface java.util.Iterator
forEachRemaining

- Constructor Detail
  - BufferIterator
```
public BufferIterator(long length,
                      Type type,
                      int chunkSize)
```
    Create a new BufferIterator with a given chunk size.
    
    Parameters:
    
    length - the total number of elements to iterate over
    
    type - the type of the primitive buffer which the next method will return at each iteration
    
    chunkSize - the size of buffer which will be used (except perhaps for the last chunk)
    
    Throws:
    
    java.lang.IllegalArgumentException - if chunkSize<=0 or length<0
  - BufferIterator
```
public BufferIterator(long length)
```
    Create a new BufferIterator with a default chunk size.
    
    Parameters:
    
    length - the total number of elements to iterate over
- Method Detail
  - next
```
public java.lang.Object next()
```
    Returns a primitive buffer of this object's type, with a length matching that of this chunk. Note it is not necessarily a new buffer created for each iteration, the one returned by this method may be the same one that it returned last time (in fact it will be, except perhaps for the last iteration when a smaller one may be required).
    
    Specified by:
    
    next in interface java.util.Iterator
    
    Returns:
    
    a primitive array of the same size as this chunk
    
    Throws:
    
    NoSuchElementException - if hasNext would return false
  - hasNext
```
public boolean hasNext()
```
    See if iteration has finished.
    
    Specified by:
    
    hasNext in interface java.util.Iterator
    
    Returns:
    
    true iff there are more chunks
  - remove
```
public void remove()
```
    Remove functionality is not implemented by this class.
    
    Specified by:
    
    remove in interface java.util.Iterator
    
    Throws:
    
    java.lang.UnsupportedOperationException - always
  - getBase
```
public long getBase()
```
    The offset of the base of the chunk most recently returned by next. This will be zero for the first chunk, and increasing by the size of the buffer returned by next with each iteration after that.
    
    Returns:
    
    the base of the current chunk
    
    Throws:
    
    java.lang.IllegalStateException - if called before the first call of next

Class BufferIterator

Constructor Summary

Method Summary

Methods inherited from class java.lang.Object

Methods inherited from interface java.util.Iterator

Constructor Detail

BufferIterator

BufferIterator

Method Detail

next

hasNext

remove

getBase