StringFormat.java Source code

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Here is the source code for StringFormat.java

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/*
 * 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;
    }
}