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Richard Domanderctrueden
Richard Domander
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Add String utils
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‎src/main/java/org/scijava/util/StringUtils.java‎

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@@ -69,9 +69,12 @@
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* @author Curtis Rueden
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* @author Chris Allan
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* @author Melissa Linkert
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* @author Richard Domander (Royal Veterinary College, London)
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*/
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public final class StringUtils {
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public static final char DEFAULT_PAD_CHAR = ' ';
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private StringUtils() {
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// NB: prevent instantiation of utility class.
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}
@@ -130,4 +133,74 @@ public static String sanitize(final String s) {
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return buf.toString();
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}
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public static boolean isNullOrEmpty(final String s) {
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return s == null || s.isEmpty();
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}
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/**
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* Calls {@link #padEnd(String, int, char)} with the {@link #DEFAULT_PAD_CHAR}
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*/
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public static String padEnd(final String s, final int length) {
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return padEnd(s, length, DEFAULT_PAD_CHAR);
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}
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/**
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* Adds characters to the end of the {@link String} to make it the given
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* length
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*
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* @param s the original string
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* @param length the length of the string with padding
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* @param padChar the character added to the end
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* @return the end padded {@link String}. Null if s is null, s if no padding
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* is not necessary
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*/
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public static String padEnd(final String s, final int length,
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final char padChar)
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{
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if (s == null) {
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return null;
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}
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final StringBuilder builder = new StringBuilder(s);
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final int padding = length - s.length();
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for (int i = 0; i < padding; i++) {
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builder.append(padChar);
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}
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return builder.toString();
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}
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/**
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* Calls {@link #padStart(String, int, char)} with the
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* {@link #DEFAULT_PAD_CHAR}
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*/
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public static String padStart(final String s, final int length) {
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return padStart(s, length, DEFAULT_PAD_CHAR);
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}
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/**
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* Adds characters to the start of the {@link String} to make it the given
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* length
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*
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* @param s the original string
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* @param length the length of the string with padding
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* @param padChar the character added to the start
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* @return the start padded {@link String}. Null if s is null, s if no padding
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* is not necessary
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*/
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public static String padStart(final String s, final int length,
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final char padChar)
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{
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if (s == null) {
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return null;
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}
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final StringBuilder builder = new StringBuilder();
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final int padding = length - s.length();
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for (int i = 0; i < padding; i++) {
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builder.append(padChar);
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}
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return builder.append(s).toString();
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}
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}

‎src/test/java/org/scijava/util/StringUtilsTest.java‎

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package org.scijava.util;
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import static org.junit.Assert.assertEquals;
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import static org.junit.Assert.assertFalse;
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import static org.junit.Assert.assertNotNull;
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import static org.junit.Assert.assertNull;
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import static org.junit.Assert.assertTrue;
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import org.junit.Test;
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/**
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* Tests for the utility methods in {@link StringUtils}
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*
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* @author Richard Domander (Royal Veterinary College, London)
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*/
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public class StringUtilsTest {
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@Test
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public void isNullOrEmptyFalseIfString() throws Exception {
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assertFalse(StringUtils.isNullOrEmpty("Fresh out of Red Leicester"));
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}
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@Test
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public void isNullOrEmpty() throws Exception {
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assertTrue(StringUtils.isNullOrEmpty(null));
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assertTrue(StringUtils.isNullOrEmpty(""));
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}
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@Test
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public void padEndNullStringReturnsNull() throws Exception {
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assertNull(StringUtils.padEnd(null, 5, '*'));
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}
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@Test
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public void padEndEmptyString() throws Exception {
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final int length = 5;
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final char padChar = '*';
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final String padded = StringUtils.padEnd("", length, padChar);
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assertNotNull(padded);
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assertFalse(padded.isEmpty());
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assertEquals(length, padded.length());
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assertTrue(padded.chars().allMatch(c -> c == padChar));
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}
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@Test
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public void padEndLengthSmaller() throws Exception {
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final String s = "Eric the fruit bat";
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final String padded = StringUtils.padEnd(s, 3, '*');
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assertEquals(s, padded);
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}
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@Test
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public void padEndLengthEqual() throws Exception {
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final String s = "Eric the cat";
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final String padded = StringUtils.padEnd(s, s.length(), '*');
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assertEquals(s, padded);
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}
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@Test
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public void padEndLengthNegative() throws Exception {
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final String s = "Eric the dog";
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final String padded = StringUtils.padEnd(s, -1, '~');
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assertEquals(s, padded);
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}
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@Test
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public void padEnd() throws Exception {
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final String s = "Eric the halibut";
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final int newLength = s.length() + 5;
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final String padded = StringUtils.padEnd(s, newLength);
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assertEquals(newLength, padded.length());
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final String padding = padded.substring(padded.length() - 5);
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assertTrue(padding.chars().allMatch(c -> c == StringUtils.DEFAULT_PAD_CHAR));
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assertEquals(s, padded.substring(0, padded.length() - 5));
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}
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@Test
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public void padStartNullStringReturnsNull() throws Exception {
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assertNull(StringUtils.padStart(null, 5, '*'));
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}
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@Test
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public void padStartEmptyString() throws Exception {
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final int length = 5;
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final char padChar = '*';
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final String padded = StringUtils.padStart("", length, padChar);
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assertNotNull(padded);
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assertFalse(padded.isEmpty());
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assertEquals(length, padded.length());
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assertTrue(padded.chars().allMatch(c -> c == padChar));
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}
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@Test
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public void padStartLengthSmaller() throws Exception {
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final String s = "Eric the dog";
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final String padded = StringUtils.padStart(s, 3, '*');
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assertEquals(s, padded);
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}
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@Test
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public void padStartLengthEqual() throws Exception {
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final String s = "Simon the prawn";
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final String padded = StringUtils.padStart(s, s.length(), '*');
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assertEquals(s, padded);
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}
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@Test
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public void padStartLengthNegative() throws Exception {
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final String s = "Norman the pike";
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final String padded = StringUtils.padStart(s, -1, '~');
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assertEquals(s, padded);
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}
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@Test
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public void padStart() throws Exception {
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final String s = "Norman the pike";
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final int newLength = s.length() + 5;
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final String padded = StringUtils.padStart(s, newLength);
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assertEquals(newLength, padded.length());
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final String padding = padded.substring(0, 5);
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assertTrue(padding.chars().allMatch(c -> c == StringUtils.DEFAULT_PAD_CHAR));
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assertEquals(s, padded.substring(5, padded.length()));
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}
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}

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