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| -rw-r--r-- | vdrmanager/src/de/bjusystems/vdrmanager/StringUtils.java | 151 |
1 files changed, 151 insertions, 0 deletions
diff --git a/vdrmanager/src/de/bjusystems/vdrmanager/StringUtils.java b/vdrmanager/src/de/bjusystems/vdrmanager/StringUtils.java new file mode 100644 index 0000000..23f1845 --- /dev/null +++ b/vdrmanager/src/de/bjusystems/vdrmanager/StringUtils.java @@ -0,0 +1,151 @@ +package de.bjusystems.vdrmanager; + +import java.util.ArrayList; +import java.util.List; + + +public class StringUtils { + + /** + * An empty immutable <code>String</code> array. + */ + public static final String[] EMPTY_STRING_ARRAY = new String[0]; + + + /** + * Performs the logic for the <code>split</code> and + * <code>splitPreserveAllTokens</code> methods that return a maximum array + * length. + * + * @param str the String to parse, may be <code>null</code> + * @param separatorChars the separate character + * @param max the maximum number of elements to include in the + * array. A zero or negative value implies no limit. + * @param preserveAllTokens if <code>true</code>, adjacent separators are + * treated as empty token separators; if <code>false</code>, adjacent + * separators are treated as one separator. + * @return an array of parsed Strings, <code>null</code> if null String input + */ + private static String[] splitWorker(String str, String separatorChars, int max, boolean preserveAllTokens) { + // Performance tuned for 2.0 (JDK1.4) + // Direct code is quicker than StringTokenizer. + // Also, StringTokenizer uses isSpace() not isWhitespace() + + if (str == null) { + return null; + } + int len = str.length(); + if (len == 0) { + return EMPTY_STRING_ARRAY; + } + List list = new ArrayList(); + int sizePlus1 = 1; + int i = 0, start = 0; + boolean match = false; + boolean lastMatch = false; + if (separatorChars == null) { + // Null separator means use whitespace + while (i < len) { + if (Character.isWhitespace(str.charAt(i))) { + if (match || preserveAllTokens) { + lastMatch = true; + if (sizePlus1++ == max) { + i = len; + lastMatch = false; + } + list.add(str.substring(start, i)); + match = false; + } + start = ++i; + continue; + } + lastMatch = false; + match = true; + i++; + } + } else if (separatorChars.length() == 1) { + // Optimise 1 character case + char sep = separatorChars.charAt(0); + while (i < len) { + if (str.charAt(i) == sep) { + if (match || preserveAllTokens) { + lastMatch = true; + if (sizePlus1++ == max) { + i = len; + lastMatch = false; + } + list.add(str.substring(start, i)); + match = false; + } + start = ++i; + continue; + } + lastMatch = false; + match = true; + i++; + } + } else { + // standard case + while (i < len) { + if (separatorChars.indexOf(str.charAt(i)) >= 0) { + if (match || preserveAllTokens) { + lastMatch = true; + if (sizePlus1++ == max) { + i = len; + lastMatch = false; + } + list.add(str.substring(start, i)); + match = false; + } + start = ++i; + continue; + } + lastMatch = false; + match = true; + i++; + } + } + if (match || (preserveAllTokens && lastMatch)) { + list.add(str.substring(start, i)); + } + return (String[]) list.toArray(new String[list.size()]); + } + + /** + * <p>Splits the provided text into an array, separators specified, + * preserving all tokens, including empty tokens created by adjacent + * separators. This is an alternative to using StringTokenizer.</p> + * + * <p>The separator is not included in the returned String array. + * Adjacent separators are treated as separators for empty tokens. + * For more control over the split use the StrTokenizer class.</p> + * + * <p>A <code>null</code> input String returns <code>null</code>. + * A <code>null</code> separatorChars splits on whitespace.</p> + * + * <pre> + * StringUtils.splitPreserveAllTokens(null, *) = null + * StringUtils.splitPreserveAllTokens("", *) = [] + * StringUtils.splitPreserveAllTokens("abc def", null) = ["abc", "def"] + * StringUtils.splitPreserveAllTokens("abc def", " ") = ["abc", "def"] + * StringUtils.splitPreserveAllTokens("abc def", " ") = ["abc", "", def"] + * StringUtils.splitPreserveAllTokens("ab:cd:ef", ":") = ["ab", "cd", "ef"] + * StringUtils.splitPreserveAllTokens("ab:cd:ef:", ":") = ["ab", "cd", "ef", ""] + * StringUtils.splitPreserveAllTokens("ab:cd:ef::", ":") = ["ab", "cd", "ef", "", ""] + * StringUtils.splitPreserveAllTokens("ab::cd:ef", ":") = ["ab", "", cd", "ef"] + * StringUtils.splitPreserveAllTokens(":cd:ef", ":") = ["", cd", "ef"] + * StringUtils.splitPreserveAllTokens("::cd:ef", ":") = ["", "", cd", "ef"] + * StringUtils.splitPreserveAllTokens(":cd:ef:", ":") = ["", cd", "ef", ""] + * </pre> + * + * @param str the String to parse, may be <code>null</code> + * @param separatorChars the characters used as the delimiters, + * <code>null</code> splits on whitespace + * @return an array of parsed Strings, <code>null</code> if null String input + * @since 2.1 + */ + public static String[] splitPreserveAllTokens(String str, String separatorChars) { + return splitWorker(str, separatorChars, -1, true); + } + +} |