org.eclipse.jgit.util.StringUtils Maven / Gradle / Ivy
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package org.eclipse.jgit.util;
import java.text.MessageFormat;
import java.util.Collection;
import org.eclipse.jgit.internal.JGitText;
/** Miscellaneous string comparison utility methods. */
public final class StringUtils {
private static final char[] LC;
static {
LC = new char['Z' + 1];
for (char c = 0; c < LC.length; c++)
LC[c] = c;
for (char c = 'A'; c <= 'Z'; c++)
LC[c] = (char) ('a' + (c - 'A'));
}
/**
* Convert the input to lowercase.
*
* This method does not honor the JVM locale, but instead always behaves as
* though it is in the US-ASCII locale. Only characters in the range 'A'
* through 'Z' are converted. All other characters are left as-is, even if
* they otherwise would have a lowercase character equivalent.
*
* @param c
* the input character.
* @return lowercase version of the input.
*/
public static char toLowerCase(final char c) {
return c <= 'Z' ? LC[c] : c;
}
/**
* Convert the input string to lower case, according to the "C" locale.
*
* This method does not honor the JVM locale, but instead always behaves as
* though it is in the US-ASCII locale. Only characters in the range 'A'
* through 'Z' are converted, all other characters are left as-is, even if
* they otherwise would have a lowercase character equivalent.
*
* @param in
* the input string. Must not be null.
* @return a copy of the input string, after converting characters in the
* range 'A'..'Z' to 'a'..'z'.
*/
public static String toLowerCase(final String in) {
final StringBuilder r = new StringBuilder(in.length());
for (int i = 0; i < in.length(); i++)
r.append(toLowerCase(in.charAt(i)));
return r.toString();
}
/**
* Test if two strings are equal, ignoring case.
*
* This method does not honor the JVM locale, but instead always behaves as
* though it is in the US-ASCII locale.
*
* @param a
* first string to compare.
* @param b
* second string to compare.
* @return true if a equals b
*/
public static boolean equalsIgnoreCase(final String a, final String b) {
if (a == b)
return true;
if (a.length() != b.length())
return false;
for (int i = 0; i < a.length(); i++) {
if (toLowerCase(a.charAt(i)) != toLowerCase(b.charAt(i)))
return false;
}
return true;
}
/**
* Compare two strings, ignoring case.
*
* This method does not honor the JVM locale, but instead always behaves as
* though it is in the US-ASCII locale.
*
* @param a
* first string to compare.
* @param b
* second string to compare.
* @return negative, zero or positive if a sorts before, is equal to, or
* sorts after b.
* @since 2.0
*/
public static int compareIgnoreCase(String a, String b) {
for (int i = 0; i < a.length() && i < b.length(); i++) {
int d = toLowerCase(a.charAt(i)) - toLowerCase(b.charAt(i));
if (d != 0)
return d;
}
return a.length() - b.length();
}
/**
* Compare two strings, honoring case.
*
* This method does not honor the JVM locale, but instead always behaves as
* though it is in the US-ASCII locale.
*
* @param a
* first string to compare.
* @param b
* second string to compare.
* @return negative, zero or positive if a sorts before, is equal to, or
* sorts after b.
* @since 2.0
*/
public static int compareWithCase(String a, String b) {
for (int i = 0; i < a.length() && i < b.length(); i++) {
int d = a.charAt(i) - b.charAt(i);
if (d != 0)
return d;
}
return a.length() - b.length();
}
/**
* Parse a string as a standard Git boolean value. See
* {@link #toBooleanOrNull(String)}.
*
* @param stringValue
* the string to parse.
* @return the boolean interpretation of {@code value}.
* @throws IllegalArgumentException
* if {@code value} is not recognized as one of the standard
* boolean names.
*/
public static boolean toBoolean(final String stringValue) {
if (stringValue == null)
throw new NullPointerException(JGitText.get().expectedBooleanStringValue);
final Boolean bool = toBooleanOrNull(stringValue);
if (bool == null)
throw new IllegalArgumentException(MessageFormat.format(JGitText.get().notABoolean, stringValue));
return bool.booleanValue();
}
/**
* Parse a string as a standard Git boolean value.
*
* The terms {@code yes}, {@code true}, {@code 1}, {@code on} can all be
* used to mean {@code true}.
*
* The terms {@code no}, {@code false}, {@code 0}, {@code off} can all be
* used to mean {@code false}.
*
* Comparisons ignore case, via {@link #equalsIgnoreCase(String, String)}.
*
* @param stringValue
* the string to parse.
* @return the boolean interpretation of {@code value} or null in case the
* string does not represent a boolean value
*/
public static Boolean toBooleanOrNull(final String stringValue) {
if (stringValue == null)
return null;
if (equalsIgnoreCase("yes", stringValue) //$NON-NLS-1$
|| equalsIgnoreCase("true", stringValue) //$NON-NLS-1$
|| equalsIgnoreCase("1", stringValue) //$NON-NLS-1$
|| equalsIgnoreCase("on", stringValue)) //$NON-NLS-1$
return Boolean.TRUE;
else if (equalsIgnoreCase("no", stringValue) //$NON-NLS-1$
|| equalsIgnoreCase("false", stringValue) //$NON-NLS-1$
|| equalsIgnoreCase("0", stringValue) //$NON-NLS-1$
|| equalsIgnoreCase("off", stringValue)) //$NON-NLS-1$
return Boolean.FALSE;
else
return null;
}
/**
* Join a collection of Strings together using the specified separator.
*
* @param parts
* Strings to join
* @param separator
* used to join
* @return a String with all the joined parts
*/
public static String join(Collection parts, String separator) {
return StringUtils.join(parts, separator, separator);
}
/**
* Join a collection of Strings together using the specified separator and a
* lastSeparator which is used for joining the second last and the last
* part.
*
* @param parts
* Strings to join
* @param separator
* separator used to join all but the two last elements
* @param lastSeparator
* separator to use for joining the last two elements
* @return a String with all the joined parts
*/
public static String join(Collection parts, String separator,
String lastSeparator) {
StringBuilder sb = new StringBuilder();
int i = 0;
int lastIndex = parts.size() - 1;
for (String part : parts) {
sb.append(part);
if (i == lastIndex - 1) {
sb.append(lastSeparator);
} else if (i != lastIndex) {
sb.append(separator);
}
i++;
}
return sb.toString();
}
private StringUtils() {
// Do not create instances
}
/**
* Test if a string is empty or null.
*
* @param stringValue
* the string to check
* @return true if the string is null or empty
*/
public static boolean isEmptyOrNull(String stringValue) {
return stringValue == null || stringValue.length() == 0;
}
}