com.hhandoko.cassandra.migration.internal.util.StringUtils Maven / Gradle / Ivy
/**
* File : StringUtils.java
* License :
* Original - Copyright (c) 2010 - 2016 Boxfuse GmbH
* Derivative - Copyright (c) 2016 - 2018 cassandra-migration Contributors
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package com.hhandoko.cassandra.migration.internal.util;
import java.util.Collection;
import java.util.Iterator;
import java.util.regex.Matcher;
import java.util.regex.Pattern;
/**
* Various string-related utilities.
*/
public class StringUtils {
/**
* Prevents instantiation.
*/
private StringUtils() {
// Do nothing.
}
/**
* Trims or pads (with spaces) this string, so it has this exact length.
*
* @param str The string to adjust. {@code null} is treated as an empty string.
* @param length The exact length to reach.
* @return The adjusted string.
*/
public static String trimOrPad(String str, int length) {
return trimOrPad(str, length, ' ');
}
/**
* Trims or pads this string, so it has this exact length.
*
* @param str The string to adjust. {@code null} is treated as an empty string.
* @param length The exact length to reach.
* @param padChar The padding character.
* @return The adjusted string.
*/
public static String trimOrPad(String str, int length, char padChar) {
String result;
if (str == null) {
result = "";
} else {
result = str;
}
if (result.length() > length) {
return result.substring(0, length);
}
while (result.length() < length) {
result += padChar;
}
return result;
}
/**
* Checks if the String contains only unicode digits. A decimal point is not a unicode digit and returns
* false.
* {@code null} will return {@code false}. An empty String ("") will return {@code true}.
*
* StringUtils.isNumeric(null) = false
* StringUtils.isNumeric("") = true
* StringUtils.isNumeric(" ") = false
* StringUtils.isNumeric("123") = true
* StringUtils.isNumeric("12 3") = false
* StringUtils.isNumeric("ab2c") = false
* StringUtils.isNumeric("12-3") = false
* StringUtils.isNumeric("12.3") = false
*
*
* @param str the String to check, may be null
* @return {@code true} if only contains digits, and is non-null
*/
public static boolean isNumeric(String str) {
return str != null && str.matches("\\d*");
}
/**
* Replaces all sequences of whitespace by a single blank. Ex.: " " to " "
*
* @param str The string to analyse.
* @return The input string, with all whitespace collapsed.
*/
public static String collapseWhitespace(String str) {
return str.replaceAll("\\s+", " ");
}
/**
* Returns the first n characters from this string, where n = count. If the string is shorter, the entire string
* will be returned. If the string is longer, it will be truncated.
*
* @param str The string to parse.
* @param count The amount of characters to return.
* @return The first n characters from this string, where n = count.
*/
public static String left(String str, int count) {
if (str == null) {
return null;
}
if (str.length() < count) {
return str;
}
return str.substring(0, count);
}
/**
* Replaces all occurrances of this originalToken in this string with this replacementToken.
*
* @param str The string to process.
* @param originalToken The token to replace.
* @param replacementToken The replacement.
* @return The transformed str.
*/
public static String replaceAll(String str, String originalToken, String replacementToken) {
return str.replaceAll(Pattern.quote(originalToken), Matcher.quoteReplacement(replacementToken));
}
/**
* Checks whether this string is not {@code null} and not empty.
*
* @param str The string to check.
* @return {@code true} if it has content, {@code false} if it is {@code null} or blank.
*/
public static boolean hasLength(String str) {
return str != null && str.length() > 0;
}
/**
* Turns this string array in one comma-delimited string.
*
* @param strings The array to process.
* @return The new comma-delimited string. An empty string if {@code null} is {@code null}.
*/
public static String arrayToCommaDelimitedString(Object[] strings) {
if (strings == null) {
return null;
}
StringBuilder builder = new StringBuilder();
for (int i = 0; i < strings.length; i++) {
if (i > 0) {
builder.append(",");
}
builder.append(String.valueOf(strings[i]));
}
return builder.toString();
}
/**
* Checks whether this string isn't {@code null} and contains at least one non-blank character.
*
* @param s The string to check.
* @return {@code true} if it has text, {@code false} if not.
*/
public static boolean hasText(String s) {
return (s != null) && (s.trim().length() > 0);
}
/**
* Splits this string into an array using these delimiters.
*
* @param str The string to split.
* @param delimiters The delimiters to use.
* @return The resulting array.
*/
public static String[] tokenizeToStringArray(String str, String delimiters) {
if (str == null) {
return null;
}
String[] tokens = str.split("[" + delimiters + "]");
for (int i = 0; i < tokens.length; i++) {
tokens[i] = tokens[i].trim();
}
return tokens;
}
/**
* Counts the number of occurrences of this token in this string.
*
* @param str The string to analyse.
* @param token The token to look for.
* @return The number of occurrences.
*/
public static int countOccurrencesOf(String str, String token) {
if (str == null || token == null || str.length() == 0 || token.length() == 0) {
return 0;
}
int count = 0;
int pos = 0;
int idx;
while ((idx = str.indexOf(token, pos)) != -1) {
++count;
pos = idx + token.length();
}
return count;
}
/**
* Replace all occurences of a substring within a string with
* another string.
*
* @param inString String to examine
* @param oldPattern String to replace
* @param newPattern String to insert
* @return a String with the replacements
*/
public static String replace(String inString, String oldPattern, String newPattern) {
if (!hasLength(inString) || !hasLength(oldPattern) || newPattern == null) {
return inString;
}
StringBuilder sb = new StringBuilder();
int pos = 0; // our position in the old string
int index = inString.indexOf(oldPattern);
// the index of an occurrence we've found, or -1
int patLen = oldPattern.length();
while (index >= 0) {
sb.append(inString.substring(pos, index));
sb.append(newPattern);
pos = index + patLen;
index = inString.indexOf(oldPattern, pos);
}
sb.append(inString.substring(pos));
// remember to append any characters to the right of a match
return sb.toString();
}
/**
* Convenience method to return a Collection as a comma-delimited
* String. E.g. useful for {@code toString()} implementations.
*
* @param collection the Collection to analyse
* @return The comma-delimited String.
*/
public static String collectionToCommaDelimitedString(Collection collection) {
return collectionToDelimitedString(collection, ", ");
}
/**
* Convenience method to return a Collection as a delimited
* String. E.g. useful for {@code toString()} implementations.
*
* @param collection the Collection to analyse
* @param delimiter The delimiter.
* @return The delimited String.
*/
public static String collectionToDelimitedString(Collection collection, String delimiter) {
if (collection == null) {
return "";
}
StringBuilder sb = new StringBuilder();
Iterator it = collection.iterator();
while (it.hasNext()) {
sb.append(it.next());
if (it.hasNext()) {
sb.append(delimiter);
}
}
return sb.toString();
}
/**
* Trim leading whitespace from the given String.
*
* @param str the String to check
* @return the trimmed String
* @see Character#isWhitespace
*/
public static String trimLeadingWhitespace(String str) {
if (!hasLength(str)) {
return str;
}
StringBuilder buf = new StringBuilder(str);
while (buf.length() > 0 && Character.isWhitespace(buf.charAt(0))) {
buf.deleteCharAt(0);
}
return buf.toString();
}
/**
* Trim trailing whitespace from the given String.
*
* @param str the String to check
* @return the trimmed String
* @see Character#isWhitespace
*/
public static String trimTrailingWhitespace(String str) {
if (!hasLength(str)) {
return str;
}
StringBuilder buf = new StringBuilder(str);
while (buf.length() > 0 && Character.isWhitespace(buf.charAt(buf.length() - 1))) {
buf.deleteCharAt(buf.length() - 1);
}
return buf.toString();
}
}