String Align Demo: extends Format
/*
* 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;
public class StringAlignDemo {
/** Demonstrate and test StringAlign class */
public static void main(String[] argv) {
String[] mesg = {"JavaFun", "JavaFun!" };
for (int i=0; i<mesg.length; i++) {
System.out.println("Input String \"" + mesg[i] + "\"");
dump(StringAlign.JUST_LEFT, 5,
new StringAlign(5, StringAlign.JUST_LEFT).format(mesg[i]));
dump(StringAlign.JUST_LEFT, 10,
new StringAlign(10, StringAlign.JUST_LEFT).format(mesg[i]));
dump(StringAlign.JUST_CENTER, 5,
new StringAlign(5, StringAlign.JUST_CENTER).format(mesg[i]));
dump(StringAlign.JUST_CENTER, 10,
new StringAlign(10, StringAlign.JUST_CENTER).format(mesg[i]));
dump(StringAlign.JUST_RIGHT, 5,
new StringAlign(5, StringAlign.JUST_RIGHT).format(mesg[i]));
dump(StringAlign.JUST_RIGHT, 10,
new StringAlign(10, StringAlign.JUST_RIGHT).format(mesg[i]));
}
}
private static void dump(int format, int len, String s) {
System.out.print((char)format + "[" + len + "]");
System.out.print(" ==> \"");
System.out.print(s);
System.out.print('"');
System.out.println();
}
}
/** Bare-minimum String formatter (string aligner).
* XXX When 1.5 is common, change from ints to enum for alignment.
*/
class StringAlign extends Format {
/* Constant for left justification. */
public static final int JUST_LEFT = 'l';
/* Constant for centering. */
public static final int JUST_CENTRE = 'c';
/* Centering Constant, 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;
/** Construct a StringAlign formatter; length and alignment are
* passed to the Constructor instead of each format() call as the
* expected common use is in repetitive formatting e.g., page numbers.
* @param nChars - the length of the output
* @param just - one of JUST_LEFT, JUST_CENTRE or JUST_RIGHT
*/
public StringAlign(int maxChars, int just) {
switch(just) {
case JUST_LEFT:
case JUST_CENTRE:
case JUST_RIGHT:
this.just = just;
break;
default:
throw new IllegalArgumentException("invalid justification arg.");
}
if (maxChars < 0) {
throw new IllegalArgumentException("maxChars must be positive.");
}
this.maxChars = maxChars;
}
/** Format a String.
* @param input _ the string to be aligned.
* @parm where - the StringBuffer to append it to.
* @param ignore - a FieldPosition (may be null, not used but
* specified by the general contract of Format).
*/
public StringBuffer format(
Object obj, StringBuffer where, FieldPosition ignore) {
String s = (String)obj;
String wanted = s.substring(0, Math.min(s.length(), maxChars));
// Get the spaces in the right place.
switch (just) {
case JUST_RIGHT:
pad(where, maxChars - wanted.length());
where.append(wanted);
break;
case JUST_CENTRE:
int toAdd = maxChars - wanted.length();
pad(where, toAdd/2);
where.append(wanted);
pad(where, toAdd - toAdd/2);
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, but not useful here. */
public Object parseObject (String source, ParsePosition pos) {
return source;
}
}
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