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'rapiddweller Common' is an open source Java library forked from Databene Commons by Volker Bergmann. It provides extensions to the Java core library by utility classes, abstract concepts and concrete implementations.

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/*
 * Copyright (C) 2004-2015 Volker Bergmann ([email protected]).
 * All rights reserved.
 *
 * Licensed 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 com.rapiddweller.common.format;


import com.rapiddweller.common.Assert;
import com.rapiddweller.common.ConversionException;
import com.rapiddweller.common.StringUtil;
import com.rapiddweller.common.converter.ThreadSafeConverter;

/**
 * Pads a string with a pad character to a given length with left/center or right alignment.
 * Created: 13.03.2014 11:40:07
 *
 * @author Volker Bergmann
 * @since 0.5.28
 */
public class StringPadder extends ThreadSafeConverter {

  private final int length;
  private final Alignment alignment;
  private final char padChar;

  /**
   * Instantiates a new String padder.
   *
   * @param length    the length
   * @param alignment the alignment
   * @param padChar   the pad char
   */
  public StringPadder(int length, Alignment alignment, char padChar) {
    super(String.class, String.class);

    // check preconditions
    if (length < 1) {
      throw new IllegalArgumentException("Not a supported padding length: " + length);
    }
    Assert.notNull(alignment, "alignment");
    if (padChar == 0) {
      throw new IllegalArgumentException("padChar must not be null");
    }

    // initialize attributes
    this.length = length;
    this.alignment = alignment;
    this.padChar = padChar;
  }


  // properties ------------------------------------------------------------------------------------------------------

  /**
   * Gets length.
   *
   * @return the length
   */
  public int getLength() {
    return length;
  }

  /**
   * Gets alignment.
   *
   * @return the alignment
   */
  public Alignment getAlignment() {
    return alignment;
  }

  /**
   * Gets pad char.
   *
   * @return the pad char
   */
  public char getPadChar() {
    return padChar;
  }


  // Converter implementation ----------------------------------------------------------------------------------------

  @Override
  public String convert(String text) throws ConversionException {
    int padLength = length - text.length();
    if (padLength < 0) {
      throw new IllegalArgumentException("Text is longer that the pad length of " + length + " characters: '" + text + "'");
    }
    switch (alignment) {
      case LEFT:
        return text + StringUtil.padString(padChar, padLength);
      case RIGHT:
        boolean neg = (padChar == '0' && text.length() > 0 && text.charAt(0) == '-');
        if (neg) {
          return "-" + StringUtil.padString('0', padLength) + text.substring(1);
        } else {
          return StringUtil.padString(padChar, padLength) + text;
        }
      case CENTER:
        return StringUtil.padString(padChar, padLength / 2) + text + StringUtil.padString(padChar, padLength - padLength / 2);
      default:
        throw new IllegalArgumentException("Not a supported Alignement: " + alignment);
    }
  }


  // java.lang.Object overrides --------------------------------------------------------------------------------------

  @Override
  public int hashCode() {
    return ((alignment.hashCode() * 31) + length) * 31 + padChar;
  }

  @Override
  public boolean equals(Object obj) {
    if (this == obj) {
      return true;
    }
    if (obj == null || getClass() != obj.getClass()) {
      return false;
    }
    final StringPadder that = (StringPadder) obj;
    return (this.alignment.equals(that.alignment)
        && this.length == that.length
        && padChar == that.padChar);
  }

  @Override
  public String toString() {
    return "" + length + alignment.getId() + padChar;
  }

}