Package org.apache.lucene.util

# Class RadixSelector

java.lang.Object
org.apache.lucene.util.Selector
org.apache.lucene.util.RadixSelector

public abstract class RadixSelector extends Selector
Radix selector.

This implementation works similarly to a MSB radix sort except that it only recurses into the sub partition that contains the desired value.

NOTE: This API is for internal purposes only and might change in incompatible ways in the next release.

- ## Constructor Summary

  Constructors
  Modifier
  Constructor
  Description
  `protected`
  `RadixSelector(int maxLength)`
  Sole constructor.

- ## Method Summary

  Modifier and Type
  Method
  Description
  `protected abstract int`
  `byteAt(int i, int k)`
  Return the k-th byte of the entry at index `i`, or `-1` if its length is less than or equal to `k`.
  `protected Selector`
  `getFallbackSelector(int d)`
  Get a fall-back selector which may assume that the first `d` bytes of all compared strings are equal.
  `void`
  `select(int from, int to, int k)`
  Reorder elements so that the element at position `k` is the same as if all elements were sorted and all other elements are partitioned around it: `[from, k)` only contains elements that are less than or equal to `k` and `(k, to)` only contains elements that are greater than or equal to `k`.

  ### Methods inherited from class org.apache.lucene.util.Selector

  `swap`

  ### Methods inherited from class java.lang.Object

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

- ## Constructor Details

  - ### RadixSelector

    protected RadixSelector(int maxLength)
    Sole constructor.
    Parameters:
      `maxLength` - the maximum length of keys, pass `Integer.MAX_VALUE` if unknown.

- ## Method Details

  - ### byteAt

    protected abstract int byteAt(int i, int k)
    Return the k-th byte of the entry at index `i`, or `-1` if its length is less than or equal to `k`. This may only be called with a value of `k` between `0` included and `maxLength` excluded.

  - ### getFallbackSelector

    protected Selector getFallbackSelector(int d)
    Get a fall-back selector which may assume that the first `d` bytes of all compared strings are equal. This fallback selector is used when the range becomes narrow or when the maximum level of recursion has been exceeded.

  - ### select

    public void select(int from, int to, int k)
    Description copied from class: `Selector`
    Reorder elements so that the element at position `k` is the same as if all elements were sorted and all other elements are partitioned around it: `[from, k)` only contains elements that are less than or equal to `k` and `(k, to)` only contains elements that are greater than or equal to `k`.
    Specified by:
      `select` in class `Selector`