Dafür gibt es unterschiedliche Varianten. Die beste ist noch, einen BreakIterator zu nutzen. NetBeans (OpenIDE) bringt hier Funktionen mit. Extrahiert und ohne Abhängigkeiten lässt sich das auf folgendes reduzieren:
import java.text.BreakIterator;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;
import java.util.StringTokenizer;
public class StringUtils
{
/**
* Indent and wrap multi-line strings.
*
* @param original the original string to wrap
* @param width the maximum width of lines
* @param breakIterator algorithm for breaking lines
* @param removeNewLines if <code>true</code>, any newlines in the original string are ignored
* @return the whole string with embedded newlines
*/
public static String wrapAndIndentString( String original, String indent, int width )
{
BreakIterator breakIterator = BreakIterator.getWordInstance();
List<String> lines = wrapStringToArray( original, width, breakIterator, true );
StringBuffer retBuf = new StringBuffer();
for ( String line : lines )
{
retBuf.append( indent );
retBuf.append( line );
retBuf.append( '\n' );
}
return retBuf.toString();
}
/**
* Wrap multi-line strings (and get the individual lines).
*
* @param original the original string to wrap
* @param width the maximum width of lines
* @param breakIterator breaks original to chars, words, sentences, depending on what instance you provide.
* @param removeNewLines if <code>true</code>, any newlines in the original string are ignored
* @return the lines after wrapping
*/
public static List<String> wrapStringToArray( String original, int width,
BreakIterator breakIterator, boolean removeNewLines )
{
if ( original.length() == 0 )
return Arrays.asList( original );
String[] workingSet;
// substitute original newlines with spaces,
// remove newlines from head and tail
if ( removeNewLines )
{
original = original.trim();
original = original.replace( '\n', ' ' );
workingSet = new String[] { original };
}
else
{
StringTokenizer tokens = new StringTokenizer( original, "\n" ); // NOI18N
int len = tokens.countTokens();
workingSet = new String[len];
for ( int i = 0; i < len; i++ )
workingSet[ i ] = tokens.nextToken();
}
if ( width < 1 )
width = 1;
if ( original.length() <= width )
return Arrays.asList( workingSet );
widthcheck :
{
boolean ok = true;
for ( int i = 0; i < workingSet.length; i++ )
{
ok = ok && (workingSet[ i ].length() < width);
if ( !ok )
break widthcheck;
}
return Arrays.asList( workingSet );
}
ArrayList<String> lines = new ArrayList<String>();
int lineStart = 0; // the position of start of currently processed line in
// the original string
for ( int i = 0; i < workingSet.length; i++ )
{
if ( workingSet[ i ].length() < width )
lines.add( workingSet[ i ] );
else
{
breakIterator.setText( workingSet[ i ] );
int nextStart = breakIterator.next();
int prevStart = 0;
do
{
while ( ((nextStart - lineStart) < width) && (nextStart != BreakIterator.DONE) )
{
prevStart = nextStart;
nextStart = breakIterator.next();
}
if ( nextStart == BreakIterator.DONE )
nextStart = prevStart = workingSet[ i ].length();
if ( prevStart == 0 )
prevStart = nextStart;
lines.add( workingSet[ i ].substring( lineStart, prevStart ) );
lineStart = prevStart;
prevStart = 0;
} while ( lineStart < workingSet[ i ].length() );
lineStart = 0;
}
}
return lines;
}
}
Schade nur, dass GWT keinen BreakIterator für die Clientseite emuliert und selbst das Paket http://code.google.com/p/gwtx/ nicht. Schade …
