String formatter: format a string to a given maximum length with left, centre, or right justification
/*
* Copyright (c) Ian F. Darwin, http://www.darwinsys.com/, 1996-2002.
* All rights reserved. Software written by Ian F. Darwin and others.
* $Id: LICENSE,v 1.8 2004/02/09 03:33:38 ian Exp $
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS''
* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
* TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS
* BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
*
* Java, the Duke mascot, and all variants of Sun's Java "steaming coffee
* cup" logo are trademarks of Sun Microsystems. Sun's, and James Gosling's,
* pioneering role in inventing and promulgating (and standardizing) the Java
* language and environment is gratefully acknowledged.
*
* The pioneering role of Dennis Ritchie and Bjarne Stroustrup, of AT&T, for
* inventing predecessor languages C and C++ is also gratefully acknowledged.
*/
import java.text.FieldPosition;
import java.text.Format;
import java.text.ParsePosition;
/**
* Bare-minimum "String formatter": format a string to a given maximum length
* with left, centre, or right justification.
*/
public class StringFormat extends Format {
/* Constant for left justification. */
public static final int JUST_LEFT = 'l';
/* Constant for centering. */
public static final int JUST_CENTRE = 'c';
/* Constant for centering, for those who spell "centre" the American way. */
public static final int JUST_CENTER = JUST_CENTRE;
/** Constant for right-justified Strings. */
public static final int JUST_RIGHT = 'r';
/** Current justification */
private int just;
/** Current max length */
private int maxChars;
public StringFormat(int maxCh, int justn) {
switch (justn) {
case JUST_LEFT:
case JUST_CENTRE:
case JUST_RIGHT:
this.just = justn;
break;
default:
throw new IllegalArgumentException("invalid justification arg.");
}
if (maxCh < 1) {
throw new IllegalArgumentException("maxChars must be positive.");
}
this.maxChars = maxCh;
}
/** Format a String */
public StringBuffer format(Object obj, StringBuffer where,
FieldPosition ignore) {
String s = (String) obj;
String wanted = s.substring(0, Math.min(s.length(), maxChars));
// If no space left for justification, return maxChars' worth */
if (wanted.length() > maxChars) {
where.append(wanted);
}
// Else get the spaces in the right place.
else
switch (just) {
case JUST_RIGHT:
pad(where, maxChars - wanted.length());
where.append(wanted);
break;
case JUST_CENTRE:
int startPos = where.length();
pad(where, (maxChars - wanted.length()) / 2);
where.append(wanted);
pad(where, (maxChars - wanted.length()) / 2);
// Adjust for "rounding error"
pad(where, maxChars - (where.length() - startPos));
break;
case JUST_LEFT:
where.append(wanted);
pad(where, maxChars - wanted.length());
break;
}
return where;
}
protected final void pad(StringBuffer to, int howMany) {
for (int i = 0; i < howMany; i++)
to.append(' ');
}
/** Convenience Routine */
String format(String s) {
return format(s, new StringBuffer(), null).toString();
}
/**
* ParseObject is required by Format interface, but not useful here.
*/
public Object parseObject(String source, ParsePosition pos) {
return source;
}
}
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