StringUtil.java :  » Portal » Open-Portal » com » sun » portal » proxylet » client » common » Java Open Source

package com.sun.portal.proxylet.client.common;

public class StringUtil
{

    public static String replaceAll( final String aSource,
             final String aFind,
             String aReplace )
    {
  int lFindLength;
  // the next statement has the side effect of throwing a null pointer
  // exception if s is null.
  if ( aSource == null ||
    aFind == null ||
    ( lFindLength = aFind.length() ) == 0 )
  {
      // If there is nothing to find, we won't try and find it.
      return aSource;
  }

  if ( aReplace == null )
  {
      // a null string and an empty string are the same
      // for replacement purposes.
      aReplace = "";
  }

  int lSourceLength = aSource.length();
  int lReplaceLength = aReplace.length();

  // We need to figure out how long our resulting string will be.
  // This is required because without it, the possible resizing
  // and copying of memory structures could lead to an unacceptable runtime.
  // In the worst case it would have to be resized n times with each
  // resize having a O(n) copy leading to an O(n^2) algorithm.
  int length;
  if ( lFindLength == lReplaceLength )
  {
      // special case in which we don't need to count the replacements
      // because the count falls out of the length formula.
      length = lSourceLength;
  }
  else
  {
      int count;
      int start;
      int end;

      // Scan s and count the number of times we find our target.
      count = 0;
      start = 0;
      while ( ( end = aSource.indexOf( aFind, start ) ) != -1 )
      {
    count++;
    start = end + lFindLength;
      }

      if ( count == 0 )
      {
    // special case in which on first pass, we find there is nothing
    // to be replaced.  No need to do a second pass or create a string buffer.
    return aSource;
      }

      length = lSourceLength - ( count * ( lFindLength - lReplaceLength ) );
  }

  int start = 0;
  int end = aSource.indexOf( aFind, start );
  if ( end == -1 )
  {
      // nothing was found in the string to replace.
      // we can get this if the find and replace strings
      // are the same length because we didn't check before.
      // in this case, we will return the original string
      return aSource;
  }
  // it looks like we actually have something to replace
  // *sigh* allocate memory for it.
  StringBuffer sb = new StringBuffer( length );

  // Scan s and do the replacements
  while ( end != -1 )
  {
      sb.append( aSource.substring( start, end ) );
      sb.append( aReplace );
      start = end + lFindLength;
      end = aSource.indexOf( aFind, start );
  }
  end = lSourceLength;
  sb.append( aSource.substring( start, end ) );

  return ( sb.toString() );
    }


    public static String replaceFirst( final String aSource,
             final String aFind,
             String aReplace )
    {
  int lFindLength;
  // the next statement has the side effect of throwing a null pointer
  // exception if s is null.
  if ( aSource == null ||
    aFind == null ||
    ( lFindLength = aFind.length() ) == 0 )
  {
      // If there is nothing to find, we won't try and find it.
      return aSource;
  }

  if ( aReplace == null )
  {
      // a null string and an empty string are the same
      // for replacement purposes.
      aReplace = "";
  }

  int lSourceLength = aSource.length();
  int lReplaceLength = aReplace.length();

  // We need to figure out how long our resulting string will be.
  // This is required because without it, the possible resizing
  // and copying of memory structures could lead to an unacceptable runtime.
  // In the worst case it would have to be resized n times with each
  // resize having a O(n) copy leading to an O(n^2) algorithm.
  int length;
  if ( lFindLength == lReplaceLength )
  {
      // special case in which we don't need to count the replacements
      // because the count falls out of the length formula.
      length = lSourceLength;
  }
  else
  {
      int count;
      int start;
      int end;

      // Scan s and count the number of times we find our target.
      count = 0;
      start = 0;
      while ( ( end = aSource.indexOf( aFind, start ) ) != -1 )
      {
    count++;
    start = end + lFindLength;
      }

      if ( count == 0 )
      {
    // special case in which on first pass, we find there is nothing
    // to be replaced.  No need to do a second pass or create a string buffer.
    return aSource;
      }

      length = lSourceLength - ( count * ( lFindLength - lReplaceLength ) );
  }

  int start = 0;
  int end = aSource.indexOf( aFind, start );
  if ( end == -1 )
  {
      // nothing was found in the string to replace.
      // we can get this if the find and replace strings
      // are the same length because we didn't check before.
      // in this case, we will return the original string
      return aSource;
  }
  // it looks like we actually have something to replace
  // *sigh* allocate memory for it.
  StringBuffer sb = new StringBuffer( length );

  // Scan s and do the replacements
  if ( end != -1 )
  {
      sb.append( aSource.substring( start, end ) );
      sb.append( aReplace );
      start = end + lFindLength;
      end = aSource.indexOf( aFind, start );
  }
  end = lSourceLength;
  sb.append( aSource.substring( start, end ) );

  return ( sb.toString() );
    }

    public static void main(String[] args)
    {
        String configList = "http=www.google.com:80;https=www.s.s.c;gopher=ss.w.s.c";

        String out = StringUtil.replaceAll(configList,"=", "://");
        System.out.println(out);
        out = StringUtil.replaceFirst(configList,"=", "://");
        System.out.println(out);
 
    }
}