com.credibledoc.iso8583packer.string.StringUtils Maven / Gradle / Ivy
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Helps to define message structure in ISO 8583 and other formats.
package com.credibledoc.iso8583packer.string;
import com.credibledoc.iso8583packer.exception.PackerRuntimeException;
/**
* Some utilities copied from the org.apache.commons.lang3.StringUtils class.
*
* @author Kyrylo Semenko
*/
public class StringUtils {
/**
* A String for a space character.
*/
public static final String SPACE = " ";
/**
* The empty String {@code ""}.
*/
public static final String EMPTY = "";
/**
* The maximum size to which the padding constant(s) can expand.
*/
private static final int PAD_LIMIT = 8192;
private StringUtils() {
throw new PackerRuntimeException("Please do not instantiate the static helper");
}
/**
* Left pad a String with a specified String.
*
* Pad to a size of {@code size}.
*
*
* StringUtils.leftPad(null, *, *) = null
* StringUtils.leftPad("", 3, "z") = "zzz"
* StringUtils.leftPad("bat", 3, "yz") = "bat"
* StringUtils.leftPad("bat", 5, "yz") = "yzbat"
* StringUtils.leftPad("bat", 8, "yz") = "yzyzybat"
* StringUtils.leftPad("bat", 1, "yz") = "bat"
* StringUtils.leftPad("bat", -1, "yz") = "bat"
* StringUtils.leftPad("bat", 5, null) = " bat"
* StringUtils.leftPad("bat", 5, "") = " bat"
*
*
* @param str the String to pad out, may be null
* @param size the size to pad to
* @param padStr the String to pad with, null or empty treated as single space
* @return left padded String or original String if no padding is necessary,
* {@code null} if null String input
*/
public static String leftPad(final String str, final int size, String padStr) {
if (str == null) {
return null;
}
if (isEmpty(padStr)) {
padStr = SPACE;
}
final int padLen = padStr.length();
final int strLen = str.length();
final int pads = size - strLen;
if (pads <= 0) {
return str; // returns original String when possible
}
if (padLen == 1 && pads <= PAD_LIMIT) {
return leftPad(str, size, padStr.charAt(0));
}
if (pads == padLen) {
return padStr.concat(str);
} else if (pads < padLen) {
return padStr.substring(0, pads).concat(str);
} else {
final char[] padding = new char[pads];
final char[] padChars = padStr.toCharArray();
for (int i = 0; i < pads; i++) {
padding[i] = padChars[i % padLen];
}
return new String(padding).concat(str);
}
}
/**
* Left pad a String with a specified character.
*
* Pad to a size of {@code size}.
*
*
* StringUtils.leftPad(null, *, *) = null
* StringUtils.leftPad("", 3, 'z') = "zzz"
* StringUtils.leftPad("bat", 3, 'z') = "bat"
* StringUtils.leftPad("bat", 5, 'z') = "zzbat"
* StringUtils.leftPad("bat", 1, 'z') = "bat"
* StringUtils.leftPad("bat", -1, 'z') = "bat"
*
*
* @param str the String to pad out, may be null
* @param size the size to pad to
* @param padChar the character to pad with
* @return left padded String or original String if no padding is necessary,
* {@code null} if null String input
* @since 2.0
*/
public static String leftPad(final String str, final int size, final char padChar) {
if (str == null) {
return null;
}
final int pads = size - str.length();
if (pads <= 0) {
return str; // returns original String when possible
}
if (pads > PAD_LIMIT) {
return leftPad(str, size, String.valueOf(padChar));
}
return repeat(padChar, pads).concat(str);
}
/**
* Returns padding using the specified delimiter repeated
* to a given length.
*
*
* StringUtils.repeat('e', 0) = ""
* StringUtils.repeat('e', 3) = "eee"
* StringUtils.repeat('e', -2) = ""
*
*
* Note: this method doesn't not support padding with
* Unicode Supplementary Characters
* as they require a pair of {@code char}s to be represented.
* If you are needing to support full I18N of your applications
* consider using {@link #repeat(String, int)} instead.
*
*
* @param ch character to repeat
* @param repeat number of times to repeat char, negative treated as zero
* @return String with repeated character
* @see #repeat(String, int)
*/
public static String repeat(final char ch, final int repeat) {
final char[] buf = new char[repeat];
for (int i = repeat - 1; i >= 0; i--) {
buf[i] = ch;
}
return new String(buf);
}
/**
* Repeat a String {@code repeat} times to form a
* new String.
*
*
* StringUtils.repeat(null, 2) = null
* StringUtils.repeat("", 0) = ""
* StringUtils.repeat("", 2) = ""
* StringUtils.repeat("a", 3) = "aaa"
* StringUtils.repeat("ab", 2) = "abab"
* StringUtils.repeat("a", -2) = ""
*
*
* @param str the String to repeat, may be null
* @param repeat number of times to repeat str, negative treated as zero
* @return a new String consisting of the original String repeated,
* {@code null} if null String input
*/
public static String repeat(final String str, final int repeat) {
// Performance tuned for 2.0 (JDK1.4)
if (str == null) {
return null;
}
if (repeat <= 0) {
return EMPTY;
}
final int inputLength = str.length();
if (repeat == 1 || inputLength == 0) {
return str;
}
if (inputLength == 1 && repeat <= PAD_LIMIT) {
return repeat(str.charAt(0), repeat);
}
final int outputLength = inputLength * repeat;
switch (inputLength) {
case 1 :
return repeat(str.charAt(0), repeat);
case 2 :
final char ch0 = str.charAt(0);
final char ch1 = str.charAt(1);
final char[] output2 = new char[outputLength];
for (int i = repeat * 2 - 2; i >= 0; i--, i--) {
output2[i] = ch0;
output2[i + 1] = ch1;
}
return new String(output2);
default :
final StringBuilder buf = new StringBuilder(outputLength);
for (int i = 0; i < repeat; i++) {
buf.append(str);
}
return buf.toString();
}
}
/**
* Checks if a CharSequence is empty ("") or null.
*
*
* StringUtils.isEmpty(null) = true
* StringUtils.isEmpty("") = true
* StringUtils.isEmpty(" ") = false
* StringUtils.isEmpty("bob") = false
* StringUtils.isEmpty(" bob ") = false
*
*
* NOTE: This method changed in Lang version 2.0.
* It no longer trims the CharSequence.
* That functionality is available in isBlank().
*
* @param cs the CharSequence to check, may be null
* @return {@code true} if the CharSequence is empty or null
* @since 3.0 Changed signature from isEmpty(String) to isEmpty(CharSequence)
*/
public static boolean isEmpty(final CharSequence cs) {
return cs == null || cs.length() == 0;
}
/**
* Checks if the CharSequence contains only Unicode digits.
* A decimal point is not a Unicode digit and returns false.
*
* {@code null} will return {@code false}.
* An empty CharSequence (length()=0) will return {@code false}.
*
* Note that the method does not allow for a leading sign, either positive or negative.
* Also, if a String passes the numeric test, it may still generate a NumberFormatException
* when parsed by Integer.parseInt or Long.parseLong, e.g. if the value is outside the range
* for int or long respectively.
*
*
* StringUtils.isNumeric(null) = false
* StringUtils.isNumeric("") = false
* StringUtils.isNumeric(" ") = false
* StringUtils.isNumeric("123") = true
* StringUtils.isNumeric("\u0967\u0968\u0969") = true
* StringUtils.isNumeric("12 3") = false
* StringUtils.isNumeric("ab2c") = false
* StringUtils.isNumeric("12-3") = false
* StringUtils.isNumeric("12.3") = false
* StringUtils.isNumeric("-123") = false
* StringUtils.isNumeric("+123") = false
*
*
* @param cs the CharSequence to check, may be null
* @return {@code true} if only contains digits, and is non-null
* @since 3.0 Changed signature from isNumeric(String) to isNumeric(CharSequence)
* @since 3.0 Changed "" to return false and not true
*/
public static boolean isNumeric(final CharSequence cs) {
if (isEmpty(cs)) {
return false;
}
final int sz = cs.length();
for (int i = 0; i < sz; i++) {
if (!Character.isDigit(cs.charAt(i))) {
return false;
}
}
return true;
}
}