Format a percentage for presentation to the user : Number Format « Data Type « Java Tutorial






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 * 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.
 */


import java.io.PrintWriter;
import java.io.StringWriter;
import java.net.InetAddress;
import java.net.URI;
import java.net.URISyntaxException;
import java.net.UnknownHostException;
import java.text.DateFormat;
import java.text.DecimalFormat;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Date;
import java.util.List;
import java.util.StringTokenizer;
import java.util.Collection;


/**
 * General string utils
 */
public class StringUtils {

  final public static char COMMA = ',';
  final public static String COMMA_STR = ",";
  final public static char ESCAPE_CHAR = '\\';
  private static DecimalFormat oneDecimal = new DecimalFormat("0.0");
  
  /**
   * Format a percentage for presentation to the user.
   * @param done the percentage to format (0.0 to 1.0)
   * @param digits the number of digits past the decimal point
   * @return a string representation of the percentage
   */
  public static String formatPercent(double done, int digits) {
    DecimalFormat percentFormat = new DecimalFormat("0.00%");
    double scale = Math.pow(10.0, digits+2);
    double rounded = Math.floor(done * scale);
    percentFormat.setDecimalSeparatorAlwaysShown(false);
    percentFormat.setMinimumFractionDigits(digits);
    percentFormat.setMaximumFractionDigits(digits);
    return percentFormat.format(rounded / scale);
  }
}








2.14.Number Format
2.14.1.Number formatting helps make your numbers more readable.
2.14.2.Specifying Precision
2.14.3.Applied to strings, the precision specifier specifies the maximum field length
2.14.4.Illustrating the precision specifier
2.14.5.Add leading zeros to a number
2.14.6.NumberFormat.getInstance()
2.14.7.NumberFormat.getCurrencyInstance(Locale.ENGLISH)
2.14.8.NumberFormat: Minimum Integer Digits, Maximum/Minimum Fraction Digits
2.14.9.Number format with FieldPosition
2.14.10.NumberFormat.getPercentInstance(Locale.ENGLISH)
2.14.11.A number formatter for logarithmic values. This formatter does not support parsing.
2.14.12.Format a percentage for presentation to the user
2.14.13.Get Percent Value
2.14.14.Helper class for format number and currency