Hi
I have a method that I would like to contribute to the StringUtils
class. I unfortunately can't access a CVS server on the internet, so I
included the method and its test in this mail. I'd appreciate it if
someone can have a look and add the source if it is acceptable.
The method basically replaces multiple strings in a String, but is very
efficient. The description of the method is in the Javadoc.
Regards,
Gerhard
Here is method to add to org.apache.commons.lang.StringUtils
/**
* <p>Replace all occurrences of multiple strings in a string.</p>
*
* <p>It is functionally equivalent to calling
* replaceAll(searchString, replaceString) repeatedly on
<code>text</code>
* for all the strings you want to replace, but much faster </p>
*
* <p><code>replaceMap</code> maps search strings to replacement
strings.
* Each key in the map will be replaced by its value in
<code>text</code>.
* </p>
*
* @param text String to replace strings in. May be null
* @param replaceMap Maps search strings to replacement strings.
* @return string with all values replaced. <code>null</code> if
* text was null
*/
public static String replace(String text, Map replaceMap) {
if(isEmpty(text)) {
return text;
}
StringBuffer buff = new StringBuffer(text.length());
//map each replace string and it's next position in text
TreeMap indexMap = new TreeMap();
//populate indexMap with it's initial values
for (Iterator iter = replaceMap.keySet().iterator();
iter.hasNext();) {
String key = (String) iter.next();
if(isBlank(key)) {
continue;
}
int idx = text.indexOf(key);
if(idx >= 0) {
indexMap.put(new Integer(idx), key);
}
}
//if there is nothing to replace
if(indexMap.isEmpty()) return text;
int prevIdx = 0;
while(indexMap.size() > 0) {
Integer idxI = (Integer)indexMap.firstKey();
int idx = idxI.intValue();
String keyS = (String)indexMap.remove(idxI);
buff.append(text.substring(prevIdx, idx));
buff.append((String)replaceMap.get(keyS));
prevIdx = idx + keyS.length();
idx = text.indexOf(keyS, prevIdx);
if(idx > 0) {
indexMap.put(new Integer(idx), keyS);
}
}
buff.append(text.substring(prevIdx));
return buff.toString();
}
Here is the test method to add to StringUtilsTest.
public void testReplace_StringMap() {
Map replaceMapEmpty = new HashMap();
Map replaceMap1 = new HashMap();
replaceMap1.put("foo", "bar");
replaceMap1.put("boo", "far");
Map replaceMap2 = new HashMap();
replaceMap2.put("foo", "");
Map replaceMap3 = new HashMap();
replaceMap3.put("", "foo");
assertEquals(null, StringUtils.replace(null, replaceMapEmpty));
assertEquals(null, StringUtils.replace(null, replaceMap1));
assertEquals("", StringUtils.replace("", replaceMapEmpty));
assertEquals("", StringUtils.replace("", replaceMap1));
assertEquals("foo", StringUtils.replace("foo", replaceMapEmpty));
assertEquals("bar", StringUtils.replace("foo", replaceMap1));
assertEquals("", StringUtils.replace("foo", replaceMap2));
assertEquals("foo", StringUtils.replace("foo", replaceMap3));
assertEquals("foobar", StringUtils.replace("foobar",
replaceMapEmpty));
assertEquals("barbar", StringUtils.replace("foobar",
replaceMap1));
assertEquals("bar", StringUtils.replace("bar", replaceMap2));
assertEquals("fobar", StringUtils.replace("fobar", replaceMap1));
assertEquals("barobar", StringUtils.replace("fooobar",
replaceMap1));
assertEquals("barbar", StringUtils.replace("foofoo",
replaceMap1));
assertEquals("barfar", StringUtils.replace("fooboo",
replaceMap1));
assertEquals("barfarbarfar", StringUtils.replace("fooboofooboo",
replaceMap1));
assertEquals("barbarfarfar", StringUtils.replace("foofoobooboo",
replaceMap1));
}
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