org.apache.lucene.util

## Class StringHelper

- java.lang.Object
- - org.apache.lucene.util.StringHelper

-     public abstract class StringHelper
      extends Object

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

- - ### Field Summary

    Fields
    Modifier and Type | Field and Description
    --- | ---
    `static int` | `GOOD_FAST_HASH_SEED` Pass this as the seed to `murmurhash3_x86_32(byte[], int, int, int)`.
    `static int` | `ID_LENGTH` length in bytes of an ID

  - ### Method Summary

    All Methods Static Methods Concrete Methods
    Modifier and Type | Method and Description
    --- | ---
    `static int` | `bytesDifference(BytesRef priorTerm, BytesRef currentTerm)` Compares two `BytesRef`, element by element, and returns the number of elements common to both arrays (from the start of each).
    `static boolean` | `endsWith(BytesRef ref, BytesRef suffix)` Returns `true` iff the ref ends with the given suffix.
    `static String` | `idToString(byte[] id)` Helper method to render an ID as a string, for debugging
    `static BytesRef` | `intsRefToBytesRef(IntsRef ints)` Just converts each int in the incoming `IntsRef` to each byte in the returned `BytesRef`, throwing `IllegalArgumentException` if any int value is out of bounds for a byte.
    `static int` | `murmurhash3_x86_32(byte[] data, int offset, int len, int seed)` Returns the MurmurHash3_x86_32 hash.
    `static int` | `murmurhash3_x86_32(BytesRef bytes, int seed)`
    `static byte[]` | `randomId()` Generates a non-cryptographic globally unique id.
    `static int` | `sortKeyLength(BytesRef priorTerm, BytesRef currentTerm)` Returns the length of `currentTerm` needed for use as a sort key.
    `static boolean` | `startsWith(byte[] ref, BytesRef prefix)` Returns `true` iff the ref starts with the given prefix.
    `static boolean` | `startsWith(BytesRef ref, BytesRef prefix)` Returns `true` iff the ref starts with the given prefix.

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

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

- - ### Field Detail

    - #### GOOD_FAST_HASH_SEED

          public static final int GOOD_FAST_HASH_SEED

      Pass this as the seed to `murmurhash3_x86_32(byte[], int, int, int)`.

    - #### ID_LENGTH

          public static final int ID_LENGTH

      length in bytes of an ID
      See Also:
        Constant Field Values

  - ### Method Detail

    - #### bytesDifference

          public static int bytesDifference(BytesRef priorTerm,
                                            BytesRef currentTerm)

      Compares two `BytesRef`, element by element, and returns the number of elements common to both arrays (from the start of each). This method assumes currentTerm comes after priorTerm.
      Parameters:
        `priorTerm` - The first `BytesRef` to compare
        `currentTerm` - The second `BytesRef` to compare
      Returns:
        The number of common elements (from the start of each).

    - #### sortKeyLength

          public static int sortKeyLength(BytesRef priorTerm,
                                          BytesRef currentTerm)

      Returns the length of `currentTerm` needed for use as a sort key. so that `BytesRef.compareTo(BytesRef)` still returns the same result. This method assumes currentTerm comes after priorTerm.

    - #### startsWith

          public static boolean startsWith(byte[] ref,
                                           BytesRef prefix)

      Returns `true` iff the ref starts with the given prefix. Otherwise `false`.
      Parameters:
        `ref` - the `byte[]` to test
        `prefix` - the expected prefix
      Returns:
        Returns `true` iff the ref starts with the given prefix. Otherwise `false`.

    - #### startsWith

          public static boolean startsWith(BytesRef ref,
                                           BytesRef prefix)

      Returns `true` iff the ref starts with the given prefix. Otherwise `false`.
      Parameters:
        `ref` - the `BytesRef` to test
        `prefix` - the expected prefix
      Returns:
        Returns `true` iff the ref starts with the given prefix. Otherwise `false`.

    - #### endsWith

          public static boolean endsWith(BytesRef ref,
                                         BytesRef suffix)

      Returns `true` iff the ref ends with the given suffix. Otherwise `false`.
      Parameters:
        `ref` - the `BytesRef` to test
        `suffix` - the expected suffix
      Returns:
        Returns `true` iff the ref ends with the given suffix. Otherwise `false`.

    - #### murmurhash3_x86_32

          public static int murmurhash3_x86_32(byte[] data,
                                               int offset,
                                               int len,
                                               int seed)

      Returns the MurmurHash3_x86_32 hash. Original source/tests at https://github.com/yonik/java_util/

    - #### murmurhash3_x86_32

          public static int murmurhash3_x86_32(BytesRef bytes,
                                               int seed)

    - #### randomId

          public static byte[] randomId()

      Generates a non-cryptographic globally unique id.

    - #### idToString

          public static String idToString(byte[] id)

      Helper method to render an ID as a string, for debugging

      Returns the string `(null)` if the id is null. Otherwise, returns a string representation for debugging. Never throws an exception. The returned string may indicate if the id is definitely invalid.

    - #### intsRefToBytesRef

          public static BytesRef intsRefToBytesRef(IntsRef ints)

      Just converts each int in the incoming `IntsRef` to each byte in the returned `BytesRef`, throwing `IllegalArgumentException` if any int value is out of bounds for a byte.

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