java.lang.Object
- org.apache.druid.java.util.common.StringUtils

```
public class StringUtils
extends Object
```
As of OpenJDK / Oracle JDK 8, the JVM is optimized around String charset variable instead of Charset passing, that is exploited in toUtf8(String) and fromUtf8(byte[]).

Field Summary

Fields
Modifier and Type Field Description

static byte[] EMPTY_BYTES

static Charset UTF8_CHARSET
Deprecated.

static String UTF8_STRING

Constructor Summary

Constructors
Constructor Description

StringUtils()

Method Summary

All Methods Static Methods Concrete Methods
Modifier and Type	Method	Description
`static String`	`chop(String s, int maxBytes)`	Returns the string truncated to maxBytes.
`static int`	`compareUnicode(String a, String b)`	Compares two Java Strings in Unicode code-point order.
`static int`	`compareUtf8(byte[] a, byte[] b)`	Compares two UTF-8 byte strings in Unicode code-point order.
`static int`	`compareUtf8UsingJavaStringOrdering(byte[] a, byte[] b)`	Compares two UTF-8 byte strings in UTF-16 code-unit order.
`static int`	`compareUtf8UsingJavaStringOrdering(byte byte1, byte byte2)`	Compares two bytes from UTF-8 strings in such a way that the entire byte arrays are compared in UTF-16 code-unit order.
`static int`	`compareUtf8UsingJavaStringOrdering(ByteBuffer buf1, int position1, int length1, ByteBuffer buf2, int position2, int length2)`	Compares two UTF-8 byte strings in UTF-16 code-unit order.
`static byte[]`	`decodeBase64(byte[] input)`	Decode an input byte array using the `Base64` encoding scheme and return a newly-allocated byte array
`static byte[]`	`decodeBase64String(String input)`	Decode an input string using the `Base64` encoding scheme and return a newly-allocated byte array
`static String`	`emptyToNullNonDruidDataString(String string)`	Returns the given string if it is nonempty; `null` otherwise.
`static byte[]`	`encodeBase64(byte[] input)`	Convert an input byte array into a newly-allocated byte array using the `Base64` encoding scheme
`static String`	`encodeBase64String(byte[] input)`	Convert an input byte array into a string using the `Base64` encoding scheme
`static String`	`encodeForFormat(String s)`	Encodes a string "s" for insertion into a format string.
`static int`	`estimatedBinaryLengthAsUTF8(String value)`
`static String`	`fastLooseChop(String s, int maxBytes)`	Shorten "s" to "maxBytes" chars.
`static String`	`format(String message, Object... formatArgs)`	Equivalent of String.format(Locale.ENGLISH, message, formatArgs).
`static String`	`fromUtf8(byte[] bytes)`
`static String`	`fromUtf8(byte[] bytes, int offset, int length)`
`static String`	`fromUtf8(it.unimi.dsi.fastutil.bytes.ByteArrayList buffer)`
`static String`	`fromUtf8(ByteBuffer buffer)`	Decodes a UTF-8 string from the remaining bytes of a non-null buffer.
`static String`	`fromUtf8(ByteBuffer buffer, int numBytes)`	Decodes a UTF-8 String from `numBytes` bytes starting at the current position of a buffer.
`static String`	`fromUtf8Nullable(ByteBuffer buffer)`	If buffer is Decodes a UTF-8 string from the remaining bytes of a buffer.
`static String`	`getResource(Object ref, String resource)`
`static String`	`lpad(String base, int len, String pad)`	Returns the string left-padded with the string pad to a length of len characters.
`static String`	`maybeRemoveLeadingSlash(String s)`
`static String`	`maybeRemoveTrailingSlash(String s)`
`static String`	`nonStrictFormat(String message, Object... formatArgs)`	Formats the string as `format(String, Object...)`, but instead of failing on illegal format, returns the concatenated format string and format arguments.
`static String`	`nullToEmptyNonDruidDataString(String string)`	Returns the given string if it is non-null; the empty string otherwise.
`static String`	`removeChar(String s, char c)`	Removes all occurrences of the given char from the given string.
`static String`	`repeat(String s, int count)`	Returns a string whose value is the concatenation of the string `s` repeated `count` times.
`static String`	`replace(String s, String target, String replacement)`	Replaces all occurrences of the given target substring in the given string with the given replacement string.
`static String`	`replaceChar(String s, char c, String replacement)`	Replaces all occurrences of the given char in the given string with the given replacement string.
`static String`	`rpad(String base, int len, String pad)`	Returns the string right-padded with the string pad to a length of len characters.
`static String`	`toLowerCase(String s)`
`static String`	`toUpperCase(String s)`
`static byte[]`	`toUtf8(String string)`	Converts a string to a UTF-8 byte array.
`static ByteBuffer`	`toUtf8ByteBuffer(String string)`	Converts a string to UTF-8 bytes, returning them as a newly-allocated on-heap `ByteBuffer`.
`static byte[]`	`toUtf8Nullable(String string)`
`static int`	`toUtf8WithLimit(String string, ByteBuffer byteBuffer)`	Encodes "string" into the buffer "byteBuffer", using no more than the number of bytes remaining in the buffer.
`static byte[]`	`toUtf8WithNullToEmpty(String string)`
`static String`	`urlDecode(String s)`
`static String`	`urlEncode(String s)`	Encodes a String in application/x-www-form-urlencoded format, with one exception: "+" in the encoded form is replaced with "%20".
`static String`	`utf8Base64(String input)`	Convert an input to base 64 and return the utf8 string of that byte array

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

- Field Detail
  - EMPTY_BYTES
```
public static final byte[] EMPTY_BYTES
```
  - UTF8_CHARSET
```
@Deprecated
public static final Charset UTF8_CHARSET
```
    Deprecated.
  - UTF8_STRING
```
public static final String UTF8_STRING
```
- Constructor Detail
  - StringUtils
```
public StringUtils()
```
- Method Detail
  - estimatedBinaryLengthAsUTF8
```
public static int estimatedBinaryLengthAsUTF8(String value)
```
  - toUtf8WithNullToEmpty
```
public static byte[] toUtf8WithNullToEmpty(String string)
```
  - compareUnicode
```
public static int compareUnicode(String a,
                                 String b)
```
    Compares two Java Strings in Unicode code-point order. Order is consistent with compareUtf8(byte[], byte[]), but is not consistent with String.compareTo(String).
  - compareUtf8
```
public static int compareUtf8(byte[] a,
                              byte[] b)
```
    Compares two UTF-8 byte strings in Unicode code-point order. Equivalent to a comparison of the two byte arrays as if they were unsigned bytes. Order is consistent with compareUnicode(String, String), but is not consistent with String.compareTo(String). For an ordering consistent with String.compareTo(String), use compareUtf8UsingJavaStringOrdering(byte[], byte[]) instead.
  - compareUtf8UsingJavaStringOrdering
```
public static int compareUtf8UsingJavaStringOrdering(byte[] a,
                                                     byte[] b)
```
    Compares two UTF-8 byte strings in UTF-16 code-unit order. Order is consistent with String.compareTo(String), but is not consistent with compareUnicode(String, String) or compareUtf8(byte[], byte[]).
  - compareUtf8UsingJavaStringOrdering
```
public static int compareUtf8UsingJavaStringOrdering(ByteBuffer buf1,
                                                     int position1,
                                                     int length1,
                                                     ByteBuffer buf2,
                                                     int position2,
                                                     int length2)
```
    Compares two UTF-8 byte strings in UTF-16 code-unit order. Order is consistent with String.compareTo(String), but is not consistent with compareUnicode(String, String) or compareUtf8(byte[], byte[]).
  - compareUtf8UsingJavaStringOrdering
```
public static int compareUtf8UsingJavaStringOrdering(byte byte1,
                                                     byte byte2)
```
    Compares two bytes from UTF-8 strings in such a way that the entire byte arrays are compared in UTF-16 code-unit order. Compatible with compareUtf8UsingJavaStringOrdering(byte[], byte[]) and compareUtf8UsingJavaStringOrdering(ByteBuffer, int, int, ByteBuffer, int, int).
  - fromUtf8
```
public static String fromUtf8(byte[] bytes)
```
  - fromUtf8
```
public static String fromUtf8(byte[] bytes,
                              int offset,
                              int length)
```
  - fromUtf8
```
public static String fromUtf8(ByteBuffer buffer,
                              int numBytes)
```
    Decodes a UTF-8 String from numBytes bytes starting at the current position of a buffer. Advances the position of the buffer by numBytes.
  - fromUtf8
```
public static String fromUtf8(ByteBuffer buffer)
```
    Decodes a UTF-8 string from the remaining bytes of a non-null buffer. Advances the position of the buffer by Buffer.remaining(). Use fromUtf8Nullable(ByteBuffer) if the buffer might be null.
  - fromUtf8
```
public static String fromUtf8(it.unimi.dsi.fastutil.bytes.ByteArrayList buffer)
```
  - fromUtf8Nullable
```
@Nullable
public static String fromUtf8Nullable(@Nullable
                                      ByteBuffer buffer)
```
    If buffer is Decodes a UTF-8 string from the remaining bytes of a buffer. Advances the position of the buffer by Buffer.remaining(). If the value is null, this method returns null. If the buffer will never be null, use fromUtf8(ByteBuffer) instead.
  - toUtf8
```
public static byte[] toUtf8(String string)
```
    Converts a string to a UTF-8 byte array.
    
    Throws:
    
    NullPointerException - if "string" is null
  - toUtf8ByteBuffer
```
@Nullable
public static ByteBuffer toUtf8ByteBuffer(@Nullable
                                          String string)
```
    Converts a string to UTF-8 bytes, returning them as a newly-allocated on-heap ByteBuffer. If "string" is null, returns null.
  - toUtf8WithLimit
```
public static int toUtf8WithLimit(String string,
                                  ByteBuffer byteBuffer)
```
    Encodes "string" into the buffer "byteBuffer", using no more than the number of bytes remaining in the buffer. Will only encode whole characters. The byteBuffer's position and limit may be changed during operation, but will be reset before this method call ends.
    
    Returns:
    
    the number of bytes written, which may be shorter than the full encoded string length if there is not enough room in the output buffer.
  - toUtf8Nullable
```
@Nullable
public static byte[] toUtf8Nullable(@Nullable
                                    String string)
```
  - format
```
public static String format(String message,
                            Object... formatArgs)
```
    Equivalent of String.format(Locale.ENGLISH, message, formatArgs).
  - nonStrictFormat
```
public static String nonStrictFormat(String message,
                                     Object... formatArgs)
```
    Formats the string as format(String, Object...), but instead of failing on illegal format, returns the concatenated format string and format arguments. Should be used for unimportant formatting like logging, exception messages, typically not directly.
  - encodeForFormat
```
@Nullable
public static String encodeForFormat(@Nullable
                                     String s)
```
    Encodes a string "s" for insertion into a format string. Returns null if the input is null.
  - toLowerCase
```
public static String toLowerCase(String s)
```
  - toUpperCase
```
public static String toUpperCase(String s)
```
  - urlEncode
```
@Nullable
public static String urlEncode(@Nullable
                               String s)
```
    Encodes a String in application/x-www-form-urlencoded format, with one exception: "+" in the encoded form is replaced with "%20". application/x-www-form-urlencoded encodes spaces as "+", but we use this to encode non-form data as well.
    
    Parameters:
    
    s - String to be encoded
    
    Returns:
    
    application/x-www-form-urlencoded format encoded String, but with "+" replaced with "%20".
  - urlDecode
```
@Nullable
public static String urlDecode(String s)
```
  - maybeRemoveLeadingSlash
```
public static String maybeRemoveLeadingSlash(String s)
```
  - maybeRemoveTrailingSlash
```
public static String maybeRemoveTrailingSlash(String s)
```
  - removeChar
```
public static String removeChar(String s,
                                char c)
```
    Removes all occurrences of the given char from the given string. This method is an optimal version of s.replace("c", "").
  - replaceChar
```
public static String replaceChar(String s,
                                 char c,
                                 String replacement)
```
    Replaces all occurrences of the given char in the given string with the given replacement string. This method is an optimal version of s.replace("c", replacement).
  - replace
```
public static String replace(String s,
                             String target,
                             String replacement)
```
    Replaces all occurrences of the given target substring in the given string with the given replacement string. This method is an optimal version of s.replace(target, replacement).
  - nullToEmptyNonDruidDataString
```
public static String nullToEmptyNonDruidDataString(@Nullable
                                                   String string)
```
    Returns the given string if it is non-null; the empty string otherwise. This method should only be used at places where null to empty conversion is irrelevant to null handling of the data.
    
    Parameters:
    
    string - the string to test and possibly return
    
    Returns:
    
    string itself if it is non-null; "" if it is null
  - emptyToNullNonDruidDataString
```
@Nullable
public static String emptyToNullNonDruidDataString(@Nullable
                                                   String string)
```
    Returns the given string if it is nonempty; null otherwise. This method should only be used at places where null to empty conversion is irrelevant to null handling of the data.
    
    Parameters:
    
    string - the string to test and possibly return
    
    Returns:
    
    string itself if it is nonempty; null if it is empty or null
  - utf8Base64
```
public static String utf8Base64(String input)
```
    Convert an input to base 64 and return the utf8 string of that byte array
    
    Parameters:
    
    input - The string to convert to base64
    
    Returns:
    
    the base64 of the input in string form
  - encodeBase64
```
public static byte[] encodeBase64(byte[] input)
```
    Convert an input byte array into a newly-allocated byte array using the Base64 encoding scheme
    
    Parameters:
    
    input - The byte array to convert to base64
    
    Returns:
    
    the base64 of the input in byte array form
  - encodeBase64String
```
public static String encodeBase64String(byte[] input)
```
    Convert an input byte array into a string using the Base64 encoding scheme
    
    Parameters:
    
    input - The byte array to convert to base64
    
    Returns:
    
    the base64 of the input in string form
  - decodeBase64
```
public static byte[] decodeBase64(byte[] input)
```
    Decode an input byte array using the Base64 encoding scheme and return a newly-allocated byte array
    
    Parameters:
    
    input - The byte array to decode from base64
    
    Returns:
    
    a newly-allocated byte array
  - decodeBase64String
```
public static byte[] decodeBase64String(String input)
```
    Decode an input string using the Base64 encoding scheme and return a newly-allocated byte array
    
    Parameters:
    
    input - The string to decode from base64
    
    Returns:
    
    a newly-allocated byte array
  - repeat
```
public static String repeat(String s,
                            int count)
```
    Returns a string whose value is the concatenation of the string s repeated count times.
    If count or length is zero then the empty string is returned.
    This method may be used to create space padding for formatting text or zero padding for formatting numbers.
    
    Parameters:
    
    count - number of times to repeat
    
    Returns:
    
    A string composed of this string repeated count times or the empty string if count or length is zero.
    
    Throws:
    
    IllegalArgumentException - if the count is negative.
  - lpad
```
@Nonnull
public static String lpad(@Nonnull
                          String base,
                          int len,
                          @Nonnull
                          String pad)
```
    Returns the string left-padded with the string pad to a length of len characters. If str is longer than len, the return value is shortened to len characters. This function is migrated from flink's scala function with minor refactor https://github.com/apache/flink/blob/master/flink-table/flink-table-planner/src/main/scala/org/apache/flink/table/runtime/functions/ScalarFunctions.scala - Modified to handle empty pad string. - Padding of negative length return an empty string.
    
    Parameters:
    
    base - The base string to be padded
    
    len - The length of padded string
    
    pad - The pad string
    
    Returns:
    
    the string left-padded with pad to a length of len or null if the pad is empty or the len is less than 0.
  - rpad
```
@Nonnull
public static String rpad(@Nonnull
                          String base,
                          int len,
                          @Nonnull
                          String pad)
```
    Returns the string right-padded with the string pad to a length of len characters. If str is longer than len, the return value is shortened to len characters. This function is migrated from flink's scala function with minor refactor https://github.com/apache/flink/blob/master/flink-table/flink-table-planner/src/main/scala/org/apache/flink/table/runtime/functions/ScalarFunctions.scala - Modified to handle empty pad string. - Modified to only copy the pad string if needed (this implementation mimics lpad). - Padding of negative length return an empty string.
    
    Parameters:
    
    base - The base string to be padded
    
    len - The length of padded string
    
    pad - The pad string
    
    Returns:
    
    the string right-padded with pad to a length of len or null if the pad is empty or the len is less than 0.
  - chop
```
@Nullable
public static String chop(@Nullable
                          String s,
                          int maxBytes)
```
    Returns the string truncated to maxBytes. If given string input is shorter than maxBytes, then it remains the same.
    
    Parameters:
    
    s - The input string to possibly be truncated
    
    maxBytes - The max bytes that string input will be truncated to
    
    Returns:
    
    the string after truncated to maxBytes
  - fastLooseChop
```
@Nullable
public static String fastLooseChop(@Nullable
                                   String s,
                                   int maxBytes)
```
    Shorten "s" to "maxBytes" chars. Fast and loose because these are *chars* not *bytes*. Use chop(String, int) for slower, but accurate chopping.
  - getResource
```
public static String getResource(Object ref,
                                 String resource)
```

Modifier and Type	Field	Description
`static byte[]`	`EMPTY_BYTES`
`static Charset`	`UTF8_CHARSET`	Deprecated.
`static String`	`UTF8_STRING`

Class StringUtils

Field Summary

Constructor Summary

Method Summary

Methods inherited from class java.lang.Object

Field Detail

EMPTY_BYTES

UTF8_CHARSET

UTF8_STRING

Constructor Detail

StringUtils

Method Detail

estimatedBinaryLengthAsUTF8

toUtf8WithNullToEmpty

compareUnicode

compareUtf8

compareUtf8UsingJavaStringOrdering

compareUtf8UsingJavaStringOrdering

compareUtf8UsingJavaStringOrdering

fromUtf8

fromUtf8

fromUtf8

fromUtf8

fromUtf8

fromUtf8Nullable

toUtf8

toUtf8ByteBuffer

toUtf8WithLimit

toUtf8Nullable

format

nonStrictFormat

encodeForFormat

toLowerCase

toUpperCase

urlEncode

urlDecode

maybeRemoveLeadingSlash

maybeRemoveTrailingSlash

removeChar

replaceChar

replace

nullToEmptyNonDruidDataString

emptyToNullNonDruidDataString

utf8Base64

encodeBase64

encodeBase64String

decodeBase64

decodeBase64String

repeat

lpad

rpad

chop

fastLooseChop

getResource