org.bitlap.roaringbitmap.buffer

类 BufferIntIteratorFlyweight

java.lang.Object

org.bitlap.roaringbitmap.buffer.BufferIntIteratorFlyweight

所有已实现的接口:

java.lang.Cloneable, IntIterator, PeekableIntIterator

public class BufferIntIteratorFlyweight
extends java.lang.Object
implements PeekableIntIterator

Fast iterator minimizing the stress on the garbage collector. You can create one reusable instance of this class and then wrap(ImmutableRoaringBitmap) For better performance, consider the ImmutableRoaringBitmap.forEach(org.bitlap.roaringbitmap.IntConsumer) method.

构造器概要

构造器

构造器和说明
BufferIntIteratorFlyweight() Creates an instance that is not ready for iteration.
BufferIntIteratorFlyweight(ImmutableRoaringBitmap r) Creates an instance that is ready for iteration.

方法概要

限定符和类型	方法和说明
void	advanceIfNeeded(int minval) If needed, advance as long as the next value is smaller than minval The advanceIfNeeded method is used for performance reasons, to skip over unnecessary repeated calls to next.
PeekableIntIterator	clone() Creates a copy of the iterator.
boolean	hasNext()
int	next()
int	peekNext() Look at the next value without advancing The peek is useful when working with several iterators at once.
void	wrap(ImmutableRoaringBitmap r) Prepares a bitmap for iteration

从类继承的方法 java.lang.Object

equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

构造器详细资料

BufferIntIteratorFlyweight

public BufferIntIteratorFlyweight()

Creates an instance that is not ready for iteration. You must first call wrap(ImmutableRoaringBitmap).

BufferIntIteratorFlyweight

public BufferIntIteratorFlyweight(ImmutableRoaringBitmap r)

Creates an instance that is ready for iteration.

参数:

r - bitmap to be iterated over

方法详细资料

clone

public PeekableIntIterator clone()

从接口复制的说明: PeekableIntIterator

Creates a copy of the iterator.

指定者:

clone 在接口中 IntIterator

指定者:

clone 在接口中 PeekableIntIterator

覆盖:

clone 在类中 java.lang.Object

返回:

a clone of the current iterator

hasNext

public boolean hasNext()

指定者:

hasNext 在接口中 IntIterator

返回:

whether there is another value

next

public int next()

指定者:

next 在接口中 IntIterator

返回:

next integer value

wrap

public void wrap(ImmutableRoaringBitmap r)

Prepares a bitmap for iteration

参数:

r - bitmap to be iterated over

advanceIfNeeded

public void advanceIfNeeded(int minval)

从接口复制的说明: PeekableIntIterator

If needed, advance as long as the next value is smaller than minval The advanceIfNeeded method is used for performance reasons, to skip over unnecessary repeated calls to next. Suppose for example that you wish to compute the intersection between an ordered list of integers (e.g., int[] x = {1,4,5}) and a PeekableIntIterator. You might do it as follows...

     PeekableIntIterator j = // get an iterator
     int val = // first value from my other data structure
     j.advanceIfNeeded(val);
     while ( j.hasNext() ) {
       if(j.next() == val) {
         // ah! ah! val is in the intersection...
         // do something here
         val = // get next value?
       }
       j.advanceIfNeeded(val);
     }
     

The benefit of calling advanceIfNeeded is that each such call can be much faster than repeated calls to "next". The underlying implementation can "skip" over some data.

指定者:

advanceIfNeeded 在接口中 PeekableIntIterator

参数:

minval - threshold

peekNext

public int peekNext()

从接口复制的说明: PeekableIntIterator

Look at the next value without advancing The peek is useful when working with several iterators at once. Suppose that you have 100 iterators, and you want to compute their intersections without materializing the result. You might do it as follows...

    PriorityQueue pq = new PriorityQueue(100,
      new Comparator<PeekableIntIterator>() {
             public int compare(PeekableIntIterator a,
                                PeekableIntIterator b) {
                 return a.peek() - b.peek();
             }
         });
 
    //...  populate pq
    
    while(! pq.isEmpty() ) {
      // get iterator with a smallest value
      PeekableIntIterator pi = pq.poll();
      int x = pi.next(); // advance
      // do something with x
      if(pi.hasNext()) pq.add(pi)
    }
    

Notice how the peek method allows you to compare iterators in a way that the next method could not do.

指定者:

peekNext 在接口中 PeekableIntIterator

返回:

next value