unEscape String : String Escape « Data Type « Java

1. Java
2. Data Type
3. String Escape

unEscape String

       
/**
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you 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.
 */


import java.io.PrintWriter;
import java.io.StringWriter;
import java.net.InetAddress;
import java.net.URI;
import java.net.URISyntaxException;
import java.net.UnknownHostException;
import java.text.DateFormat;
import java.text.DecimalFormat;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Date;
import java.util.List;
import java.util.StringTokenizer;
import java.util.Collection;


/**
 * General string utils
 */
public class StringUtils {
  
  /**
   * Unescape <code>charToEscape</code> in the string 
   * with the escape char <code>escapeChar</code>
   * 
   * @param str string
   * @param escapeChar escape char
   * @param charToEscape the escaped char
   * @return an unescaped string
   */
  public static String unEscapeString(
      String str, char escapeChar, char charToEscape) {
    if (str == null) {
      return null;
    }
    StringBuilder result = new StringBuilder(str.length());
    boolean hasPreEscape = false;
    for (int i=0; i<str.length(); i++) {
      char curChar = str.charAt(i);
      if (hasPreEscape) {
        if (curChar != escapeChar && curChar != charToEscape) {
          // no special char
          throw new IllegalArgumentException("Illegal escaped string " + str + 
              " unescaped " + escapeChar + " at " + (i-1));
        } 
        // otherwise discard the escape char
        result.append(curChar);
        hasPreEscape = false;
      } else {
        if (curChar == charToEscape) {
          throw new IllegalArgumentException("Illegal escaped string " + str + 
              " unescaped " + charToEscape + " at " + i);
        } else if (curChar == escapeChar) {
          hasPreEscape = true;
        } else {
          result.append(curChar);
        }
      }
    }
    if (hasPreEscape ) {
      throw new IllegalArgumentException("Illegal escaped string " + str + 
          ", not expecting " + charToEscape + " in the end." );
    }
    return result.toString();
  }
  
  
}

   
    
    
    
    
    
    
  

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