![]() ![]() ![]() |
Start of Tutorial > Start of Trail > Start of Lesson | Search |
Applications that format text or that perform line wrapping must locate potential line breaks. You can find these line breaks, or boundaries, with aBreakIterator
that has been created with thegetLineInstance
method:BreakIterator lineIterator = BreakIterator.getLineInstance(currentLocale);This
BreakIterator
determines the positions in a string where text can break to continue on the next line. The positions detected by theBreakIterator
are potential line breaks. The actual line breaks displayed on the screen may not be the same.The two examples that follow use the
markBoundaries
method ofBreakIteratorDemo.java
to show the line boundaries detected by a
BreakIterator
. ThemarkBoundaries
method indicates line boundaries by printing carets (^) beneath the target string.According to a
BreakIterator
, a line boundary occurs after the termination of a sequence of whitespace characters (space, tab, new line). In the following example, note that you can break the line at any of the boundaries detected:She stopped. She said, "Hello there," and then went on. ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^Potential line breaks also occur immediately after a hyphen:
There are twenty-four hours in a day. ^ ^ ^ ^ ^ ^ ^ ^ ^The next example breaks a long string of text into fixed-length lines with a method called
formatLines
. This method uses aBreakIterator
to locate the potential line breaks. TheformatLines
method is short, simple, and, thanks to theBreakIterator
, locale-independent. Here is the source code:static void formatLines(String target, int maxLength, Locale currentLocale) { BreakIterator boundary = BreakIterator.getLineInstance(currentLocale); boundary.setText(target); int start = boundary.first(); int end = boundary.next(); int lineLength = 0; while (end != BreakIterator.DONE) { String word = target.substring(start,end); lineLength = lineLength + word.length(); if (lineLength >= maxLength) { System.out.println(); lineLength = word.length(); } System.out.print(word); start = end; end = boundary.next(); } }The
BreakIteratorDemo
program invokes theformatLines
method as follows:String moreText = "She said, \"Hello there,\" and then " + "went on down the street. When she stopped " + "to look at the fur coats in a shop window, " + "her dog growled._ \"Sorry Jake,\" she said. " + " \"I didn't know you would take it personally.\""; formatLines(moreText, 30, currentLocale);The output from this call to
formatLines
is:She said, "Hello there," and then went on down the street. When she stopped to look at the fur coats in a shop window, her dog growled. "Sorry Jake," she said. "I didn't know you would take it personally."
![]() ![]() ![]() |
Start of Tutorial > Start of Trail > Start of Lesson | Search |