• Home
• org.devefx
• validator-web
• 1.0.0-alphal
• source code
• StringUtils.java

×

Project download

Many resources are needed to download a project. Please understand that we have to compensate our server costs. Thank you in advance.
Project price only 1 $

You can buy this project and download/modify it how often you want.

org.devefx.validator.util.StringUtils Maven / Gradle / Ivy

/*
 * Copyright 2016-2017, Youqian Yue ([email protected]).
 *
 * 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 org.devefx.validator.util;

import java.util.ArrayList;
import java.util.Collection;
import java.util.Iterator;
import java.util.List;
import java.util.StringTokenizer;

public class StringUtils {
    
    /**
     * Constant representing the empty string, equal to ""
     */
    public static final String EMPTY_STRING = "";
    
    /**
     * Constant representing the default delimiter character (comma), equal to ','
     */
    public static final char DEFAULT_DELIMITER_CHAR = ',';

    /**
     * Constant representing the default quote character (double quote), equal to '"'
     */
    public static final char DEFAULT_QUOTE_CHAR = '"';

    /**
     * Check that the given CharSequence is neither {@code null} nor of length 0.
     * Note: Will return {@code true} for a CharSequence that purely consists of whitespace.
     * 
     * StringUtils.hasLength(null) = false
     * StringUtils.hasLength("") = false
     * StringUtils.hasLength(" ") = true
     * StringUtils.hasLength("Hello") = true
     * 
     * @param str the CharSequence to check (may be {@code null})
     * @return {@code true} if the CharSequence is not null and has length
     * @see #hasText(String)
     */
    public static boolean hasLength(CharSequence str) {
        return (str != null && str.length() > 0);
    }
    
    /**
     * Check that the given {@code String} is neither {@code null} nor of length 0.
     * 
Note: this method returns {@code true} for a {@code String} that
     * purely consists of whitespace.
     * @param str the {@code String} to check (may be {@code null})
     * @return {@code true} if the {@code String} is not {@code null} and has length
     * @see #hasLength(CharSequence)
     * @see #hasText(String)
     */
    public static boolean hasLength(String str) {
        return hasLength((CharSequence) str);
    }
    
    /**
     * Check whether the given CharSequence has actual text.
     * More specifically, returns {@code true} if the string not {@code null},
     * its length is greater than 0, and it contains at least one non-whitespace character.
     * 
     * StringUtils.hasText(null) = false
     * StringUtils.hasText("") = false
     * StringUtils.hasText(" ") = false
     * StringUtils.hasText("12345") = true
     * StringUtils.hasText(" 12345 ") = true
     * 
     * @param str the CharSequence to check (may be {@code null})
     * @return {@code true} if the CharSequence is not {@code null},
     * its length is greater than 0, and it does not contain whitespace only
     * @see Character#isWhitespace
     */
    public static boolean hasText(CharSequence str) {
        if (!hasLength(str)) {
            return false;
        }
        int strLen = str.length();
        for (int i = 0; i < strLen; i++) {
            if (!Character.isWhitespace(str.charAt(i))) {
                return true;
            }
        }
        return false;
    }

    /**
     * Check whether the given String has actual text.
     * More specifically, returns {@code true} if the string not {@code null},
     * its length is greater than 0, and it contains at least one non-whitespace character.
     * @param str the String to check (may be {@code null})
     * @return {@code true} if the String is not {@code null}, its length is
     * greater than 0, and it does not contain whitespace only
     * @see #hasText(CharSequence)
     */
    public static boolean hasText(String str) {
        return hasText((CharSequence) str);
    }
    
    /**
     * Tokenize the given String into a String array via a StringTokenizer.
     * Trims tokens and omits empty tokens.
     * 
The given delimiters string is supposed to consist of any number of
     * delimiter characters. Each of those characters can be used to separate
     * tokens. A delimiter is always a single character; for multi-character
     * delimiters, consider using {@code delimitedListToStringArray}
     * @param str the String to tokenize
     * @param delimiters the delimiter characters, assembled as String
     * (each of those characters is individually considered as delimiter).
     * @return an array of the tokens
     * @see java.util.StringTokenizer
     * @see String#trim()
     * @see #delimitedListToStringArray
     */
    public static String[] tokenizeToStringArray(String str, String delimiters) {
        return tokenizeToStringArray(str, delimiters, true, true);
    }
    
    /**
     * Tokenize the given String into a String array via a StringTokenizer.
     * 
The given delimiters string is supposed to consist of any number of
     * delimiter characters. Each of those characters can be used to separate
     * tokens. A delimiter is always a single character; for multi-character
     * delimiters, consider using {@code delimitedListToStringArray}
     * @param str the String to tokenize
     * @param delimiters the delimiter characters, assembled as String
     * (each of those characters is individually considered as delimiter)
     * @param trimTokens trim the tokens via String's {@code trim}
     * @param ignoreEmptyTokens omit empty tokens from the result array
     * (only applies to tokens that are empty after trimming; StringTokenizer
     * will not consider subsequent delimiters as token in the first place).
     * @return an array of the tokens ({@code null} if the input String
     * was {@code null})
     * @see java.util.StringTokenizer
     * @see String#trim()
     * @see #delimitedListToStringArray
     */
    public static String[] tokenizeToStringArray(
            String str, String delimiters, boolean trimTokens, boolean ignoreEmptyTokens) {

        if (str == null) {
            return null;
        }
        StringTokenizer st = new StringTokenizer(str, delimiters);
        List tokens = new ArrayList();
        while (st.hasMoreTokens()) {
            String token = st.nextToken();
            if (trimTokens) {
                token = token.trim();
            }
            if (!ignoreEmptyTokens || token.length() > 0) {
                tokens.add(token);
            }
        }
        return toStringArray(tokens);
    }
    
    /**
     * Copy the given Collection into a String array.
     * The Collection must contain String elements only.
     * @param collection the Collection to copy
     * @return the String array ({@code null} if the passed-in
     * Collection was {@code null})
     */
    public static String[] toStringArray(Collection collection) {
        if (collection == null) {
            return null;
        }
        return collection.toArray(new String[collection.size()]);
    }
    
    /**
     * Returns a 'cleaned' representation of the specified argument.  'Cleaned' is defined as the following:
     * 

     * 

     * 
If the specified String is null, return null
     * 
If not null, {@link String#trim() trim()} it.
     * 
If the trimmed string is equal to the empty String (i.e. ""), return null
     * 
If the trimmed string is not the empty string, return the trimmed version
.
     * 
     * 

     * Therefore this method always ensures that any given string has trimmed text, and if it doesn't, null
     * is returned.
     *
     * @param in the input String to clean.
     * @return a populated-but-trimmed String or null otherwise
     */
    public static String clean(String in) {
        String out = in;

        if (in != null) {
            out = in.trim();
            if (out.equals(EMPTY_STRING)) {
                out = null;
            }
        }

        return out;
    }
    
    public static String[] split(String line) {
        return split(line, DEFAULT_DELIMITER_CHAR);
    }

    public static String[] split(String line, char delimiter) {
        return split(line, delimiter, DEFAULT_QUOTE_CHAR);
    }

    public static String[] split(String line, char delimiter, char quoteChar) {
        return split(line, delimiter, quoteChar, quoteChar);
    }

    public static String[] split(String line, char delimiter, char beginQuoteChar, char endQuoteChar) {
        return split(line, delimiter, beginQuoteChar, endQuoteChar, false, true);
    }
    
    /**
     * Splits the specified delimited String into tokens, supporting quoted tokens so that quoted strings themselves
     * won't be tokenized.
     * 

     * This method's implementation is very loosely based (with significant modifications) on
     * Glen Smith's open-source
     * CSVReader.java
     * file.
     * 

     * That file is Apache 2.0 licensed as well, making Glen's code a great starting point for us to modify to
     * our needs.
     *
     * @param aLine          the String to parse
     * @param delimiter      the delimiter by which the line argument is to be split
     * @param beginQuoteChar the character signifying the start of quoted text (so the quoted text will not be split)
     * @param endQuoteChar   the character signifying the end of quoted text
     * @param retainQuotes   if the quotes themselves should be retained when constructing the corresponding token
     * @param trimTokens     if leading and trailing whitespace should be trimmed from discovered tokens.
     * @return the tokens discovered from parsing the given delimited line.
     */
    public static String[] split(String aLine, char delimiter, char beginQuoteChar, char endQuoteChar,
                                 boolean retainQuotes, boolean trimTokens) {
        String line = clean(aLine);
        if (line == null) {
            return null;
        }

        List tokens = new ArrayList();
        StringBuilder sb = new StringBuilder();
        boolean inQuotes = false;

        for (int i = 0; i < line.length(); i++) {

            char c = line.charAt(i);
            if (c == beginQuoteChar) {
                // this gets complex... the quote may end a quoted block, or escape another quote.
                // do a 1-char lookahead:
                if (inQuotes  // we are in quotes, therefore there can be escaped quotes in here.
                        && line.length() > (i + 1)  // there is indeed another character to check.
                        && line.charAt(i + 1) == beginQuoteChar) { // ..and that char. is a quote also.
                    // we have two quote chars in a row == one quote char, so consume them both and
                    // put one on the token. we do *not* exit the quoted text.
                    sb.append(line.charAt(i + 1));
                    i++;
                } else {
                    inQuotes = !inQuotes;
                    if (retainQuotes) {
                        sb.append(c);
                    }
                }
            } else if (c == endQuoteChar) {
                inQuotes = !inQuotes;
                if (retainQuotes) {
                    sb.append(c);
                }
            } else if (c == delimiter && !inQuotes) {
                String s = sb.toString();
                if (trimTokens) {
                    s = s.trim();
                }
                tokens.add(s);
                sb = new StringBuilder(); // start work on next token
            } else {
                sb.append(c);
            }
        }
        String s = sb.toString();
        if (trimTokens) {
            s = s.trim();
        }
        tokens.add(s);
        return tokens.toArray(new String[tokens.size()]);
    }
    
    /**
     * Convenience method to return a Collection as a delimited (e.g. CSV)
     * String. E.g. useful for {@code toString()} implementations.
     * @param coll the Collection to display
     * @param delim the delimiter to use (probably a ",")
     * @param prefix the String to start each element with
     * @param suffix the String to end each element with
     * @return the delimited String
     */
    public static String collectionToDelimitedString(Collection coll, String delim, String prefix, String suffix) {
        if (coll == null || coll.isEmpty()) {
            return "";
        }
        StringBuilder sb = new StringBuilder();
        Iterator it = coll.iterator();
        while (it.hasNext()) {
            sb.append(prefix).append(it.next()).append(suffix);
            if (it.hasNext()) {
                sb.append(delim);
            }
        }
        return sb.toString();
    }

    /**
     * Convenience method to return a Collection as a delimited (e.g. CSV)
     * String. E.g. useful for {@code toString()} implementations.
     * @param coll the Collection to display
     * @param delim the delimiter to use (probably a ",")
     * @return the delimited String
     */
    public static String collectionToDelimitedString(Collection coll, String delim) {
        return collectionToDelimitedString(coll, delim, "", "");
    }

    /**
     * Convenience method to return a Collection as a CSV String.
     * E.g. useful for {@code toString()} implementations.
     * @param coll the Collection to display
     * @return the delimited String
     */
    public static String collectionToCommaDelimitedString(Collection coll) {
        return collectionToDelimitedString(coll, ",");
    }
}