Package net.sourceforge.pmd.util

Class StringUtil

java.lang.Object

net.sourceforge.pmd.util.StringUtil

public final class StringUtil
extends Object

String-related utility functions. See also StringUtils.

Author:

BrianRemedios, Clément Fournier

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
static enum	StringUtil.CaseConvention

Method Summary

Modifier and Type	Method	Description
static StringBuilder	append(StringBuilder sb, CharSequence charSeq)	Like StringBuilder.append(CharSequence), but uses an optimized implementation if the charsequence happens to be a Chars.
static String	asString(Object[] items, String separator)	Formats all items onto a string with separators if more than one exists, return an empty string if the items are null or empty.
static int	columnNumberAt(CharSequence charSeq, int offsetInclusive)	Returns the (1-based) column number of the character at the given index.
static String	elide(String string, int maxOutputLength, String ellipsis)	Truncate the given string to some maximum length.
static String	escapeJava(String str)	Replaces unprintable characters by their escaped (or unicode escaped) equivalents in the given string
static String	escapeWhitespace(Object o)	Replace some whitespace characters so they are visually apparent.
static @NonNull String	inDoubleQuotes(String expected)
static String	inSingleQuotes(String s)
static boolean	isSame(String s1, String s2, boolean trim, boolean ignoreCase, boolean standardizeWhitespace)	Are the two String values the same.
static int	lineNumberAt(CharSequence charSeq, int offsetInclusive)	Returns the (1-based) line number of the character at the given index.
static List<Chars>	linesWithTrimIndent(Chars source)	Returns a list of
static String	nullToEmpty(String value)	Return the empty string if the parameter is null.
static String	percentageString(double val, int numDecimals)	Formats a double to a percentage, keeping numDecimal decimal places.
static String	quoteMessageFormat(String str)	Escape the string so that it appears literally when interpreted by a MessageFormat.
static String	removedInvalidXml10Characters(String text)	Remove characters, that are not allowed in XML 1.0 documents.
static String	removeDoubleQuotes(String string)	Like removeSurrounding with a double quote as a delimiter.
static String	removeSurrounding(String string, char delimiter)	If the string starts and ends with the delimiter, returns the substring within the delimiters.
static String	substringAfterLast(String str, int c)	Returns the substring following the last occurrence of the given character.
static StringBuilder	trimIndent(Chars string)	Trim common indentation in the lines of the string.
static void	trimIndentInPlace(List<Chars> lines)	Trim the common indentation of each line in place in the input list.
static String	withoutPrefixes(String text, String... prefixes)	Checks for the existence of any of the listed prefixes on the non-null text and removes them.

Methods inherited from class java.lang.Object

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

Method Details

inSingleQuotes

public static String inSingleQuotes(String s)

inDoubleQuotes

public static @NonNull String inDoubleQuotes(String expected)

lineNumberAt

public static int lineNumberAt(CharSequence charSeq,
 int offsetInclusive)

Returns the (1-based) line number of the character at the given index. Line terminators (\r, \n) are assumed to be on the line they *end* and not on the following line. The method also accepts that the given offset be the length of the string (in which case there's no targeted character), to get the line number of a character that would be inserted at the end of the string.

     lineNumberAt("a\nb", 0)  = 1
     lineNumberAt("a\nb", 1)  = 1
     lineNumberAt("a\nb", 2)  = 2
     lineNumberAt("a\nb", 3)  = 2  // charAt(3) doesn't exist though
     lineNumberAt("a\nb", 4)  = -1

     lineNumberAt("", 0) = 1
     lineNumberAt("", _) = -1

 

Parameters:

charSeq - Char sequence

offsetInclusive - Offset in the sequence of the targeted character. May be the length of the sequence.

Returns:

-1 if the offset is not in [0, length], otherwise the line number

columnNumberAt

public static int columnNumberAt(CharSequence charSeq,
 int offsetInclusive)

Returns the (1-based) column number of the character at the given index. Line terminators are by convention taken to be part of the line they end, and not the new line they start. Each character has width 1 (including \t). The method also accepts that the given offset be the length of the string (in which case there's no targeted character), to get the column number of a character that would be inserted at the end of the string.

     columnNumberAt("a\nb", 0)  = 1
     columnNumberAt("a\nb", 1)  = 2
     columnNumberAt("a\nb", 2)  = 1
     columnNumberAt("a\nb", 3)  = 2   // charAt(3) doesn't exist though
     columnNumberAt("a\nb", 4)  = -1

     columnNumberAt("a\r\n", 2)  = 3

 

Parameters:

charSeq - Char sequence

offsetInclusive - Offset in the sequence

Returns:

-1 if the offset is not in [0, length], otherwise the column number

append

public static StringBuilder append(StringBuilder sb,
 CharSequence charSeq)

Like StringBuilder.append(CharSequence), but uses an optimized implementation if the charsequence happens to be a Chars. StringBuilder already optimises the cases where the charseq is a string, a StringBuilder, or a stringBuffer. This is especially useful in parsers.

substringAfterLast

public static String substringAfterLast(String str,
 int c)

Returns the substring following the last occurrence of the given character. If the character doesn't occur, returns the whole string. This contrasts with StringUtils.substringAfterLast(String, String), which returns the empty string in that case.

Parameters:

str - String to cut

c - Delimiter

percentageString

public static String percentageString(double val,
 int numDecimals)

Formats a double to a percentage, keeping numDecimal decimal places.

Parameters:

val - a double value between 0 and 1

numDecimals - The number of decimal places to keep

Returns:

A formatted string

Throws:

IllegalArgumentException - if the double to format is not between 0 and 1

withoutPrefixes

public static String withoutPrefixes(String text,
 String... prefixes)

Checks for the existence of any of the listed prefixes on the non-null text and removes them.

Returns:

String

removedInvalidXml10Characters

public static String removedInvalidXml10Characters(String text)

Remove characters, that are not allowed in XML 1.0 documents.

Allowed characters are:

Char ::= #x9 | #xA | #xD | [#x20-#xD7FF] | [#xE000-#xFFFD] | [#x10000-#x10FFFF] // any Unicode character, excluding the surrogate blocks, FFFE, and FFFF.

(see Extensible Markup Language (XML) 1.0 (Fifth Edition)).

escapeWhitespace

public static String escapeWhitespace(Object o)

Replace some whitespace characters so they are visually apparent.

Returns:

String

linesWithTrimIndent

public static List<Chars> linesWithTrimIndent(Chars source)

Returns a list of

trimIndentInPlace

public static void trimIndentInPlace(List<Chars> lines)

Trim the common indentation of each line in place in the input list. Trailing whitespace is removed on each line. Note that blank lines do not count towards computing the max common indentation, except the last one.

Parameters:

lines - mutable list

trimIndent

public static StringBuilder trimIndent(Chars string)

Trim common indentation in the lines of the string. Like trimIndentInPlace(List) called with the list of lines and joined with \n.

isSame

public static boolean isSame(String s1,
 String s2,
 boolean trim,
 boolean ignoreCase,
 boolean standardizeWhitespace)

Are the two String values the same. The Strings can be optionally trimmed before checking. The Strings can be optionally compared ignoring case. The Strings can be have embedded whitespace standardized before comparing. Two null values are treated as equal.

Parameters:

s1 - The first String.

s2 - The second String.

trim - Indicates if the Strings should be trimmed before comparison.

ignoreCase - Indicates if the case of the Strings should ignored during comparison.

standardizeWhitespace - Indicates if the embedded whitespace should be standardized before comparison.

Returns:

true if the Strings are the same, false otherwise.

asString

public static String asString(Object[] items,
 String separator)

Formats all items onto a string with separators if more than one exists, return an empty string if the items are null or empty.

Parameters:

items - Object[]

separator - String

Returns:

String

removeSurrounding

public static String removeSurrounding(String string,
 char delimiter)

If the string starts and ends with the delimiter, returns the substring within the delimiters. Otherwise returns the original string. The start and end delimiter must be 2 separate instances.

 removeSurrounding("",     _ )  = ""
 removeSurrounding("q",   'q')  = "q"
 removeSurrounding("qq",  'q')  = ""
 removeSurrounding("q_q", 'q')  = "_"
 

removeDoubleQuotes

public static String removeDoubleQuotes(String string)

Like removeSurrounding with a double quote as a delimiter.

elide

public static String elide(String string,
 int maxOutputLength,
 String ellipsis)

Truncate the given string to some maximum length. If it needs truncation, the ellipsis string is appended. The length of the returned string is always lower-or-equal to the maxOutputLength, even when truncation occurs.

escapeJava

public static String escapeJava(String str)

Replaces unprintable characters by their escaped (or unicode escaped) equivalents in the given string

quoteMessageFormat

public static String quoteMessageFormat(String str)

Escape the string so that it appears literally when interpreted by a MessageFormat.

nullToEmpty

public static String nullToEmpty(String value)

Return the empty string if the parameter is null.