If this class is really necessary, could you consider updating it to match the latest Log4j code? As long as Drill keeps its own copy of this Strings class, it is likely to regularly hit issues with being incompatible with latest log4j releases.
If you really need to keep the copy of the log4j Strings class, the latest log4j release code seems safe in that it is self-contained (other than using core Java code).
package org.apache.logging.log4j.util;
import java.util.Iterator;
import java.util.Locale;
import java.util.Objects;
/**
* <em>Consider this class private.</em>
*
* @see <a href="http://commons.apache.org/proper/commons-lang/">Apache Commons Lang</a>
*/
public final class Strings {
/**
* The empty string.
*/
public static final String EMPTY = "";
/**
* OS-dependent line separator, defaults to {@code "\n"} if the system property {@code ""line.separator"} cannot be
* read.
*/
public static final String LINE_SEPARATOR = PropertiesUtil.getProperties().getStringProperty("line.separator",
"\n");
/**
* Returns a double quoted string.
*
* @param str a String
* @return {@code "str"}
*/
public static String dquote(final String str) {
return Chars.DQUOTE + str + Chars.DQUOTE;
}
/**
* Checks if a String is blank. A blank string is one that is either
* {@code null}, empty, or all characters are {@link Character#isWhitespace(char)}.
*
* @param s the String to check, may be {@code null}
* @return {@code true} if the String is {@code null}, empty, or or all characters are {@link Character#isWhitespace(char)}
*/
public static boolean isBlank(final String s) {
if (s == null || s.isEmpty()) {
return true;
}
for (int i = 0; i < s.length(); i++) {
char c = s.charAt(i);
if (!Character.isWhitespace(c)) {
return false;
}
}
return true;
}
/**
* <p>
* Checks if a CharSequence is empty ("") or null.
* </p>
*
* <pre>
* Strings.isEmpty(null) = true
* Strings.isEmpty("") = true
* Strings.isEmpty(" ") = false
* Strings.isEmpty("bob") = false
* Strings.isEmpty(" bob ") = false
* </pre>
*
* <p>
* NOTE: This method changed in Lang version 2.0. It no longer trims the CharSequence. That functionality is
* available in isBlank().
* </p>
*
* <p>
* Copied from Apache Commons Lang org.apache.commons.lang3.StringUtils.isEmpty(CharSequence)
* </p>
*
* @param cs the CharSequence to check, may be null
* @return {@code true} if the CharSequence is empty or null
*/
public static boolean isEmpty(final CharSequence cs) {
return cs == null || cs.length() == 0;
}
/**
* Checks if a String is not blank. The opposite of {@link #isBlank(String)}.
*
* @param s the String to check, may be {@code null}
* @return {@code true} if the String is non-{@code null} and has content after being trimmed.
*/
public static boolean isNotBlank(final String s) {
return !isBlank(s);
}
/**
* <p>
* Checks if a CharSequence is not empty ("") and not null.
* </p>
*
* <pre>
* Strings.isNotEmpty(null) = false
* Strings.isNotEmpty("") = false
* Strings.isNotEmpty(" ") = true
* Strings.isNotEmpty("bob") = true
* Strings.isNotEmpty(" bob ") = true
* </pre>
*
* <p>
* Copied from Apache Commons Lang org.apache.commons.lang3.StringUtils.isNotEmpty(CharSequence)
* </p>
*
* @param cs the CharSequence to check, may be null
* @return {@code true} if the CharSequence is not empty and not null
*/
public static boolean isNotEmpty(final CharSequence cs) {
return !isEmpty(cs);
}
/**
* <p>Joins the elements of the provided {@code Iterable} into
* a single String containing the provided elements.</p>
*
* <p>No delimiter is added before or after the list. Null objects or empty
* strings within the iteration are represented by empty strings.</p>
*
* @param iterable the {@code Iterable} providing the values to join together, may be null
* @param separator the separator character to use
* @return the joined String, {@code null} if null iterator input
*/
public static String join(final Iterable<?> iterable, final char separator) {
if (iterable == null) {
return null;
}
return join(iterable.iterator(), separator);
}
/**
* <p>Joins the elements of the provided {@code Iterator} into
* a single String containing the provided elements.</p>
*
* <p>No delimiter is added before or after the list. Null objects or empty
* strings within the iteration are represented by empty strings.</p>
*
* @param iterator the {@code Iterator} of values to join together, may be null
* @param separator the separator character to use
* @return the joined String, {@code null} if null iterator input
*/
public static String join(final Iterator<?> iterator, final char separator) {
// handle null, zero and one elements before building a buffer
if (iterator == null) {
return null;
}
if (!iterator.hasNext()) {
return EMPTY;
}
final Object first = iterator.next();
if (!iterator.hasNext()) {
return Objects.toString(first, EMPTY);
}
// two or more elements
final StringBuilder buf = new StringBuilder(256); // Java default is 16, probably too small
if (first != null) {
buf.append(first);
}
while (iterator.hasNext()) {
buf.append(separator);
final Object obj = iterator.next();
if (obj != null) {
buf.append(obj);
}
}
return buf.toString();
}
/**
* <p>Gets the leftmost {@code len} characters of a String.</p>
*
* <p>If {@code len} characters are not available, or the
* String is {@code null}, the String will be returned without
* an exception. An empty String is returned if len is negative.</p>
*
* <pre>
* StringUtils.left(null, *) = null
* StringUtils.left(*, -ve) = ""
* StringUtils.left("", *) = ""
* StringUtils.left("abc", 0) = ""
* StringUtils.left("abc", 2) = "ab"
* StringUtils.left("abc", 4) = "abc"
* </pre>
*
* <p>
* Copied from Apache Commons Lang org.apache.commons.lang3.StringUtils.
* </p>
*
* @param str the String to get the leftmost characters from, may be null
* @param len the length of the required String
* @return the leftmost characters, {@code null} if null String input
*/
public static String left(final String str, final int len) {
if (str == null) {
return null;
}
if (len < 0) {
return EMPTY;
}
if (str.length() <= len) {
return str;
}
return str.substring(0, len);
}
/**
* Returns a quoted string.
*
* @param str a String
* @return {@code 'str'}
*/
public static String quote(final String str) {
return Chars.QUOTE + str + Chars.QUOTE;
}
/**
* <p>
* Removes control characters (char <= 32) from both ends of this String returning {@code null} if the String is
* empty ("") after the trim or if it is {@code null}.
*
* <p>
* The String is trimmed using {@link String#trim()}. Trim removes start and end characters <= 32.
* </p>
*
* <pre>
* Strings.trimToNull(null) = null
* Strings.trimToNull("") = null
* Strings.trimToNull(" ") = null
* Strings.trimToNull("abc") = "abc"
* Strings.trimToNull(" abc ") = "abc"
* </pre>
*
* <p>
* Copied from Apache Commons Lang org.apache.commons.lang3.StringUtils.trimToNull(String)
* </p>
*
* @param str the String to be trimmed, may be null
* @return the trimmed String, {@code null} if only chars <= 32, empty or null String input
*/
public static String trimToNull(final String str) {
final String ts = str == null ? null : str.trim();
return isEmpty(ts) ? null : ts;
}
private Strings() {
// empty
}
/**
* Shorthand for {@code str.toUpperCase(Locale.ROOT);}
* @param str The string to upper case.
* @return a new string
* @see String#toLowerCase(Locale)
*/
public static String toRootUpperCase(final String str) {
return str.toUpperCase(Locale.ROOT);
}
/**
* Creates a new string repeating given {@code str} {@code count} times.
* @param str input string
* @param count the repetition count
* @return the new string
* @throws IllegalArgumentException if either {@code str} is null or {@code count} is negative
*/
public static String repeat(final String str, final int count) {
Objects.requireNonNull(str, "str");
if (count < 0) {
throw new IllegalArgumentException("count");
}
StringBuilder sb = new StringBuilder(str.length() * count);
for (int index = 0; index < count; index++) {
sb.append(str);
}
return sb.toString();
}
}
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