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Java example source code file (ComplexFormat.java)

This example Java source code file (ComplexFormat.java) is included in the alvinalexander.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" TM.

Learn more about this Java project at its project page.

Java - Java tags/keywords

complexformat, default_imaginary_character, fieldposition, locale, mathillegalargumentexception, mathparseexception, nodataexception, nullargumentexception, numberformat, parseposition, stringbuffer, text, util

The ComplexFormat.java Java example source code

/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.apache.commons.math3.complex;

import java.text.FieldPosition;
import java.text.NumberFormat;
import java.text.ParsePosition;
import java.util.Locale;

import org.apache.commons.math3.exception.MathIllegalArgumentException;
import org.apache.commons.math3.exception.MathParseException;
import org.apache.commons.math3.exception.NoDataException;
import org.apache.commons.math3.exception.NullArgumentException;
import org.apache.commons.math3.exception.util.LocalizedFormats;
import org.apache.commons.math3.util.CompositeFormat;

/**
 * Formats a Complex number in cartesian format "Re(c) + Im(c)i".  'i' can
 * be replaced with 'j' (or anything else), and the number format for both real
 * and imaginary parts can be configured.
 *
 */
public class ComplexFormat {

     /** The default imaginary character. */
    private static final String DEFAULT_IMAGINARY_CHARACTER = "i";
    /** The notation used to signify the imaginary part of the complex number. */
    private final String imaginaryCharacter;
    /** The format used for the imaginary part. */
    private final NumberFormat imaginaryFormat;
    /** The format used for the real part. */
    private final NumberFormat realFormat;

    /**
     * Create an instance with the default imaginary character, 'i', and the
     * default number format for both real and imaginary parts.
     */
    public ComplexFormat() {
        this.imaginaryCharacter = DEFAULT_IMAGINARY_CHARACTER;
        this.imaginaryFormat = CompositeFormat.getDefaultNumberFormat();
        this.realFormat = imaginaryFormat;
    }

    /**
     * Create an instance with a custom number format for both real and
     * imaginary parts.
     * @param format the custom format for both real and imaginary parts.
     * @throws NullArgumentException if {@code realFormat} is {@code null}.
     */
    public ComplexFormat(NumberFormat format) throws NullArgumentException {
        if (format == null) {
            throw new NullArgumentException(LocalizedFormats.IMAGINARY_FORMAT);
        }
        this.imaginaryCharacter = DEFAULT_IMAGINARY_CHARACTER;
        this.imaginaryFormat = format;
        this.realFormat = format;
    }

    /**
     * Create an instance with a custom number format for the real part and a
     * custom number format for the imaginary part.
     * @param realFormat the custom format for the real part.
     * @param imaginaryFormat the custom format for the imaginary part.
     * @throws NullArgumentException if {@code imaginaryFormat} is {@code null}.
     * @throws NullArgumentException if {@code realFormat} is {@code null}.
      */
    public ComplexFormat(NumberFormat realFormat, NumberFormat imaginaryFormat)
        throws NullArgumentException {
        if (imaginaryFormat == null) {
            throw new NullArgumentException(LocalizedFormats.IMAGINARY_FORMAT);
        }
        if (realFormat == null) {
            throw new NullArgumentException(LocalizedFormats.REAL_FORMAT);
        }

        this.imaginaryCharacter = DEFAULT_IMAGINARY_CHARACTER;
        this.imaginaryFormat = imaginaryFormat;
        this.realFormat = realFormat;
    }

    /**
     * Create an instance with a custom imaginary character, and the default
     * number format for both real and imaginary parts.
     * @param imaginaryCharacter The custom imaginary character.
     * @throws NullArgumentException if {@code imaginaryCharacter} is
     * {@code null}.
     * @throws NoDataException if {@code imaginaryCharacter} is an
     * empty string.
     */
    public ComplexFormat(String imaginaryCharacter)
        throws NullArgumentException, NoDataException {
        this(imaginaryCharacter, CompositeFormat.getDefaultNumberFormat());
    }

    /**
     * Create an instance with a custom imaginary character, and a custom number
     * format for both real and imaginary parts.
     * @param imaginaryCharacter The custom imaginary character.
     * @param format the custom format for both real and imaginary parts.
     * @throws NullArgumentException if {@code imaginaryCharacter} is
     * {@code null}.
     * @throws NoDataException if {@code imaginaryCharacter} is an
     * empty string.
     * @throws NullArgumentException if {@code format} is {@code null}.
     */
    public ComplexFormat(String imaginaryCharacter, NumberFormat format)
        throws NullArgumentException, NoDataException {
        this(imaginaryCharacter, format, format);
    }

    /**
     * Create an instance with a custom imaginary character, a custom number
     * format for the real part, and a custom number format for the imaginary
     * part.
     *
     * @param imaginaryCharacter The custom imaginary character.
     * @param realFormat the custom format for the real part.
     * @param imaginaryFormat the custom format for the imaginary part.
     * @throws NullArgumentException if {@code imaginaryCharacter} is
     * {@code null}.
     * @throws NoDataException if {@code imaginaryCharacter} is an
     * empty string.
     * @throws NullArgumentException if {@code imaginaryFormat} is {@code null}.
     * @throws NullArgumentException if {@code realFormat} is {@code null}.
     */
    public ComplexFormat(String imaginaryCharacter,
                         NumberFormat realFormat,
                         NumberFormat imaginaryFormat)
        throws NullArgumentException, NoDataException {
        if (imaginaryCharacter == null) {
            throw new NullArgumentException();
        }
        if (imaginaryCharacter.length() == 0) {
            throw new NoDataException();
        }
        if (imaginaryFormat == null) {
            throw new NullArgumentException(LocalizedFormats.IMAGINARY_FORMAT);
        }
        if (realFormat == null) {
            throw new NullArgumentException(LocalizedFormats.REAL_FORMAT);
        }

        this.imaginaryCharacter = imaginaryCharacter;
        this.imaginaryFormat = imaginaryFormat;
        this.realFormat = realFormat;
    }

    /**
     * Get the set of locales for which complex formats are available.
     * <p>This is the same set as the {@link NumberFormat} set.

* @return available complex format locales. */ public static Locale[] getAvailableLocales() { return NumberFormat.getAvailableLocales(); } /** * This method calls {@link #format(Object,StringBuffer,FieldPosition)}. * * @param c Complex object to format. * @return A formatted number in the form "Re(c) + Im(c)i". */ public String format(Complex c) { return format(c, new StringBuffer(), new FieldPosition(0)).toString(); } /** * This method calls {@link #format(Object,StringBuffer,FieldPosition)}. * * @param c Double object to format. * @return A formatted number. */ public String format(Double c) { return format(new Complex(c, 0), new StringBuffer(), new FieldPosition(0)).toString(); } /** * Formats a {@link Complex} object to produce a string. * * @param complex the object to format. * @param toAppendTo where the text is to be appended * @param pos On input: an alignment field, if desired. On output: the * offsets of the alignment field * @return the value passed in as toAppendTo. */ public StringBuffer format(Complex complex, StringBuffer toAppendTo, FieldPosition pos) { pos.setBeginIndex(0); pos.setEndIndex(0); // format real double re = complex.getReal(); CompositeFormat.formatDouble(re, getRealFormat(), toAppendTo, pos); // format sign and imaginary double im = complex.getImaginary(); StringBuffer imAppendTo; if (im < 0.0) { toAppendTo.append(" - "); imAppendTo = formatImaginary(-im, new StringBuffer(), pos); toAppendTo.append(imAppendTo); toAppendTo.append(getImaginaryCharacter()); } else if (im > 0.0 || Double.isNaN(im)) { toAppendTo.append(" + "); imAppendTo = formatImaginary(im, new StringBuffer(), pos); toAppendTo.append(imAppendTo); toAppendTo.append(getImaginaryCharacter()); } return toAppendTo; } /** * Format the absolute value of the imaginary part. * * @param absIm Absolute value of the imaginary part of a complex number. * @param toAppendTo where the text is to be appended. * @param pos On input: an alignment field, if desired. On output: the * offsets of the alignment field. * @return the value passed in as toAppendTo. */ private StringBuffer formatImaginary(double absIm, StringBuffer toAppendTo, FieldPosition pos) { pos.setBeginIndex(0); pos.setEndIndex(0); CompositeFormat.formatDouble(absIm, getImaginaryFormat(), toAppendTo, pos); if (toAppendTo.toString().equals("1")) { // Remove the character "1" if it is the only one. toAppendTo.setLength(0); } return toAppendTo; } /** * Formats a object to produce a string. {@code obj} must be either a * {@link Complex} object or a {@link Number} object. Any other type of * object will result in an {@link IllegalArgumentException} being thrown. * * @param obj the object to format. * @param toAppendTo where the text is to be appended * @param pos On input: an alignment field, if desired. On output: the * offsets of the alignment field * @return the value passed in as toAppendTo. * @see java.text.Format#format(java.lang.Object, java.lang.StringBuffer, java.text.FieldPosition) * @throws MathIllegalArgumentException is {@code obj} is not a valid type. */ public StringBuffer format(Object obj, StringBuffer toAppendTo, FieldPosition pos) throws MathIllegalArgumentException { StringBuffer ret = null; if (obj instanceof Complex) { ret = format( (Complex)obj, toAppendTo, pos); } else if (obj instanceof Number) { ret = format(new Complex(((Number)obj).doubleValue(), 0.0), toAppendTo, pos); } else { throw new MathIllegalArgumentException(LocalizedFormats.CANNOT_FORMAT_INSTANCE_AS_COMPLEX, obj.getClass().getName()); } return ret; } /** * Access the imaginaryCharacter. * @return the imaginaryCharacter. */ public String getImaginaryCharacter() { return imaginaryCharacter; } /** * Access the imaginaryFormat. * @return the imaginaryFormat. */ public NumberFormat getImaginaryFormat() { return imaginaryFormat; } /** * Returns the default complex format for the current locale. * @return the default complex format. */ public static ComplexFormat getInstance() { return getInstance(Locale.getDefault()); } /** * Returns the default complex format for the given locale. * @param locale the specific locale used by the format. * @return the complex format specific to the given locale. */ public static ComplexFormat getInstance(Locale locale) { NumberFormat f = CompositeFormat.getDefaultNumberFormat(locale); return new ComplexFormat(f); } /** * Returns the default complex format for the given locale. * @param locale the specific locale used by the format. * @param imaginaryCharacter Imaginary character. * @return the complex format specific to the given locale. * @throws NullArgumentException if {@code imaginaryCharacter} is * {@code null}. * @throws NoDataException if {@code imaginaryCharacter} is an * empty string. */ public static ComplexFormat getInstance(String imaginaryCharacter, Locale locale) throws NullArgumentException, NoDataException { NumberFormat f = CompositeFormat.getDefaultNumberFormat(locale); return new ComplexFormat(imaginaryCharacter, f); } /** * Access the realFormat. * @return the realFormat. */ public NumberFormat getRealFormat() { return realFormat; } /** * Parses a string to produce a {@link Complex} object. * * @param source the string to parse. * @return the parsed {@link Complex} object. * @throws MathParseException if the beginning of the specified string * cannot be parsed. */ public Complex parse(String source) throws MathParseException { ParsePosition parsePosition = new ParsePosition(0); Complex result = parse(source, parsePosition); if (parsePosition.getIndex() == 0) { throw new MathParseException(source, parsePosition.getErrorIndex(), Complex.class); } return result; } /** * Parses a string to produce a {@link Complex} object. * * @param source the string to parse * @param pos input/ouput parsing parameter. * @return the parsed {@link Complex} object. */ public Complex parse(String source, ParsePosition pos) { int initialIndex = pos.getIndex(); // parse whitespace CompositeFormat.parseAndIgnoreWhitespace(source, pos); // parse real Number re = CompositeFormat.parseNumber(source, getRealFormat(), pos); if (re == null) { // invalid real number // set index back to initial, error index should already be set pos.setIndex(initialIndex); return null; } // parse sign int startIndex = pos.getIndex(); char c = CompositeFormat.parseNextCharacter(source, pos); int sign = 0; switch (c) { case 0 : // no sign // return real only complex number return new Complex(re.doubleValue(), 0.0); case '-' : sign = -1; break; case '+' : sign = 1; break; default : // invalid sign // set index back to initial, error index should be the last // character examined. pos.setIndex(initialIndex); pos.setErrorIndex(startIndex); return null; } // parse whitespace CompositeFormat.parseAndIgnoreWhitespace(source, pos); // parse imaginary Number im = CompositeFormat.parseNumber(source, getRealFormat(), pos); if (im == null) { // invalid imaginary number // set index back to initial, error index should already be set pos.setIndex(initialIndex); return null; } // parse imaginary character if (!CompositeFormat.parseFixedstring(source, getImaginaryCharacter(), pos)) { return null; } return new Complex(re.doubleValue(), im.doubleValue() * sign); } }

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