Example usage for java.lang CharSequence charAt

Introduction

In this page you can find the example usage for java.lang CharSequence charAt.

Prototype

char charAt(int index);

Source Link

Document

Returns the char value at the specified index.

Usage

From source file:bfile.util.StringUtils.java

/**
 * <p>Checks if the CharSequence contains only Unicode digits.
 * A decimal point is not a Unicode digit and returns false.</p>
 *
 * <p>{@code null} will return {@code false}.
 * An empty CharSequence (length()=0) will return {@code false}.</p>
 *
 * <p>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.</p>
 *
 * <pre>//from   ww  w  .j  a va 2  s.c om
 * 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
 * </pre>
 *
 * @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;
}

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From source file:bfile.util.StringUtils.java

/**
 * <p>Checks if the CharSequence contains only whitespace.</p>
 *
 * <p>{@code null} will return {@code false}.
 * An empty CharSequence (length()=0) will return {@code true}.</p>
 *
 * <pre>// w  w w .j  ava  2s. c  o  m
 * StringUtils.isWhitespace(null)   = false
 * StringUtils.isWhitespace("")     = true
 * StringUtils.isWhitespace("  ")   = true
 * StringUtils.isWhitespace("abc")  = false
 * StringUtils.isWhitespace("ab2c") = false
 * StringUtils.isWhitespace("ab-c") = false
 * </pre>
 *
 * @param cs  the CharSequence to check, may be null
 * @return {@code true} if only contains whitespace, and is non-null
 * @since 2.0
 * @since 3.0 Changed signature from isWhitespace(String) to isWhitespace(CharSequence)
 */
public static boolean isWhitespace(final CharSequence cs) {
    if (cs == null) {
        return false;
    }
    final int sz = cs.length();
    for (int i = 0; i < sz; i++) {
        if (Character.isWhitespace(cs.charAt(i)) == false) {
            return false;
        }
    }
    return true;
}

---

From source file:bfile.util.StringUtils.java

/**
 * <p>Checks if the CharSequence contains only Unicode letters, digits
 * or space ({@code ' '}).</p>/*w ww. j  a v  a  2 s  . c om*/
 *
 * <p>{@code null} will return {@code false}.
 * An empty CharSequence (length()=0) will return {@code true}.</p>
 *
 * <pre>
 * StringUtils.isAlphanumericSpace(null)   = false
 * StringUtils.isAlphanumericSpace("")     = true
 * StringUtils.isAlphanumericSpace("  ")   = true
 * StringUtils.isAlphanumericSpace("abc")  = true
 * StringUtils.isAlphanumericSpace("ab c") = true
 * StringUtils.isAlphanumericSpace("ab2c") = true
 * StringUtils.isAlphanumericSpace("ab-c") = false
 * </pre>
 *
 * @param cs  the CharSequence to check, may be null
 * @return {@code true} if only contains letters, digits or space,
 *  and is non-null
 * @since 3.0 Changed signature from isAlphanumericSpace(String) to isAlphanumericSpace(CharSequence)
 */
public static boolean isAlphanumericSpace(final CharSequence cs) {
    if (cs == null) {
        return false;
    }
    final int sz = cs.length();
    for (int i = 0; i < sz; i++) {
        if (Character.isLetterOrDigit(cs.charAt(i)) == false && cs.charAt(i) != ' ') {
            return false;
        }
    }
    return true;
}

---

From source file:bfile.util.StringUtils.java

/**
 * <p>Checks if the CharSequence contains only Unicode letters or digits.</p>
 *
 * <p>{@code null} will return {@code false}.
 * An empty CharSequence (length()=0) will return {@code false}.</p>
 *
 * <pre>//from www  .j  a  va 2  s  .  c om
 * StringUtils.isAlphanumeric(null)   = false
 * StringUtils.isAlphanumeric("")     = false
 * StringUtils.isAlphanumeric("  ")   = false
 * StringUtils.isAlphanumeric("abc")  = true
 * StringUtils.isAlphanumeric("ab c") = false
 * StringUtils.isAlphanumeric("ab2c") = true
 * StringUtils.isAlphanumeric("ab-c") = false
 * </pre>
 *
 * @param cs  the CharSequence to check, may be null
 * @return {@code true} if only contains letters or digits,
 *  and is non-null
 * @since 3.0 Changed signature from isAlphanumeric(String) to isAlphanumeric(CharSequence)
 * @since 3.0 Changed "" to return false and not true
 */
public static boolean isAlphanumeric(final CharSequence cs) {
    if (isEmpty(cs)) {
        return false;
    }
    final int sz = cs.length();
    for (int i = 0; i < sz; i++) {
        if (Character.isLetterOrDigit(cs.charAt(i)) == false) {
            return false;
        }
    }
    return true;
}

---

From source file:bfile.util.StringUtils.java

/**
 * <p>Checks if the CharSequence contains only ASCII printable characters.</p>
 *
 * <p>{@code null} will return {@code false}.
 * An empty CharSequence (length()=0) will return {@code true}.</p>
 *
 * <pre>//from ww  w  .  jav a 2 s.  c  o m
 * StringUtils.isAsciiPrintable(null)     = false
 * StringUtils.isAsciiPrintable("")       = true
 * StringUtils.isAsciiPrintable(" ")      = true
 * StringUtils.isAsciiPrintable("Ceki")   = true
 * StringUtils.isAsciiPrintable("ab2c")   = true
 * StringUtils.isAsciiPrintable("!ab-c~") = true
 * StringUtils.isAsciiPrintable("\u0020") = true
 * StringUtils.isAsciiPrintable("\u0021") = true
 * StringUtils.isAsciiPrintable("\u007e") = true
 * StringUtils.isAsciiPrintable("\u007f") = false
 * StringUtils.isAsciiPrintable("Ceki G\u00fclc\u00fc") = false
 * </pre>
 *
 * @param cs the CharSequence to check, may be null
 * @return {@code true} if every character is in the range
 *  32 thru 126
 * @since 2.1
 * @since 3.0 Changed signature from isAsciiPrintable(String) to isAsciiPrintable(CharSequence)
 */
public static boolean isAsciiPrintable(final CharSequence cs) {
    if (cs == null) {
        return false;
    }
    final int sz = cs.length();
    for (int i = 0; i < sz; i++) {
        if (CharUtils.isAsciiPrintable(cs.charAt(i)) == false) {
            return false;
        }
    }
    return true;
}

---

From source file:bfile.util.StringUtils.java

/**
 * <p>Checks if the CharSequence contains only lowercase characters.</p>
 *
 * <p>{@code null} will return {@code false}.
 * An empty CharSequence (length()=0) will return {@code false}.</p>
 *
 * <pre>/*w  w  w  .jav a  2  s  .c o m*/
 * StringUtils.isAllLowerCase(null)   = false
 * StringUtils.isAllLowerCase("")     = false
 * StringUtils.isAllLowerCase("  ")   = false
 * StringUtils.isAllLowerCase("abc")  = true
 * StringUtils.isAllLowerCase("abC")  = false
 * StringUtils.isAllLowerCase("ab c") = false
 * StringUtils.isAllLowerCase("ab1c") = false
 * StringUtils.isAllLowerCase("ab/c") = false
 * </pre>
 *
 * @param cs  the CharSequence to check, may be null
 * @return {@code true} if only contains lowercase characters, and is non-null
 * @since 2.5
 * @since 3.0 Changed signature from isAllLowerCase(String) to isAllLowerCase(CharSequence)
 */
public static boolean isAllLowerCase(final CharSequence cs) {
    if (cs == null || isEmpty(cs)) {
        return false;
    }
    final int sz = cs.length();
    for (int i = 0; i < sz; i++) {
        if (Character.isLowerCase(cs.charAt(i)) == false) {
            return false;
        }
    }
    return true;
}

---

From source file:bfile.util.StringUtils.java

/**
 * <p>Checks if the CharSequence contains only uppercase characters.</p>
 *
 * <p>{@code null} will return {@code false}.
 * An empty String (length()=0) will return {@code false}.</p>
 *
 * <pre>/*from  www .j a v a  2  s. c om*/
 * StringUtils.isAllUpperCase(null)   = false
 * StringUtils.isAllUpperCase("")     = false
 * StringUtils.isAllUpperCase("  ")   = false
 * StringUtils.isAllUpperCase("ABC")  = true
 * StringUtils.isAllUpperCase("aBC")  = false
 * StringUtils.isAllUpperCase("A C")  = false
 * StringUtils.isAllUpperCase("A1C")  = false
 * StringUtils.isAllUpperCase("A/C")  = false
 * </pre>
 *
 * @param cs the CharSequence to check, may be null
 * @return {@code true} if only contains uppercase characters, and is non-null
 * @since 2.5
 * @since 3.0 Changed signature from isAllUpperCase(String) to isAllUpperCase(CharSequence)
 */
public static boolean isAllUpperCase(final CharSequence cs) {
    if (cs == null || isEmpty(cs)) {
        return false;
    }
    final int sz = cs.length();
    for (int i = 0; i < sz; i++) {
        if (Character.isUpperCase(cs.charAt(i)) == false) {
            return false;
        }
    }
    return true;
}

---

From source file:bfile.util.StringUtils.java

/**
 * <p>Search a CharSequence to find the first index of any
 * character not in the given set of characters.</p>
 *
 * <p>A {@code null} CharSequence will return {@code -1}.
 * A {@code null} or empty search string will return {@code -1}.</p>
 *
 * <pre>/*from  w  w  w. j  a v a 2 s .c  o m*/
 * StringUtils.indexOfAnyBut(null, *)            = -1
 * StringUtils.indexOfAnyBut("", *)              = -1
 * StringUtils.indexOfAnyBut(*, null)            = -1
 * StringUtils.indexOfAnyBut(*, "")              = -1
 * StringUtils.indexOfAnyBut("zzabyycdxx", "za") = 3
 * StringUtils.indexOfAnyBut("zzabyycdxx", "")   = -1
 * StringUtils.indexOfAnyBut("aba","ab")         = -1
 * </pre>
 *
 * @param seq  the CharSequence to check, may be null
 * @param searchChars  the chars to search for, may be null
 * @return the index of any of the chars, -1 if no match or null input
 * @since 2.0
 * @since 3.0 Changed signature from indexOfAnyBut(String, String) to indexOfAnyBut(CharSequence, CharSequence)
 */
public static int indexOfAnyBut(final CharSequence seq, final CharSequence searchChars) {
    if (isEmpty(seq) || isEmpty(searchChars)) {
        return INDEX_NOT_FOUND;
    }
    final int strLen = seq.length();
    for (int i = 0; i < strLen; i++) {
        final char ch = seq.charAt(i);
        final boolean chFound = CharSequenceUtils.indexOf(searchChars, ch, 0) >= 0;
        if (i + 1 < strLen && Character.isHighSurrogate(ch)) {
            final char ch2 = seq.charAt(i + 1);
            if (chFound && CharSequenceUtils.indexOf(searchChars, ch2, 0) < 0) {
                return i;
            }
        } else {
            if (!chFound) {
                return i;
            }
        }
    }
    return INDEX_NOT_FOUND;
}

---

From source file:bfile.util.StringUtils.java

/**
 * <p>Compares two CharSequences, and returns the index at which the
 * CharSequences begin to differ.</p>
 *
 * <p>For example,/*from   ww w.j a  va  2 s .  c  o m*/
 * {@code indexOfDifference("i am a machine", "i am a robot") -> 7}</p>
 *
 * <pre>
 * StringUtils.indexOfDifference(null, null) = -1
 * StringUtils.indexOfDifference("", "") = -1
 * StringUtils.indexOfDifference("", "abc") = 0
 * StringUtils.indexOfDifference("abc", "") = 0
 * StringUtils.indexOfDifference("abc", "abc") = -1
 * StringUtils.indexOfDifference("ab", "abxyz") = 2
 * StringUtils.indexOfDifference("abcde", "abxyz") = 2
 * StringUtils.indexOfDifference("abcde", "xyz") = 0
 * </pre>
 *
 * @param cs1  the first CharSequence, may be null
 * @param cs2  the second CharSequence, may be null
 * @return the index where cs1 and cs2 begin to differ; -1 if they are equal
 * @since 2.0
 * @since 3.0 Changed signature from indexOfDifference(String, String) to
 * indexOfDifference(CharSequence, CharSequence)
 */
public static int indexOfDifference(final CharSequence cs1, final CharSequence cs2) {
    if (cs1 == cs2) {
        return INDEX_NOT_FOUND;
    }
    if (cs1 == null || cs2 == null) {
        return 0;
    }
    int i;
    for (i = 0; i < cs1.length() && i < cs2.length(); ++i) {
        if (cs1.charAt(i) != cs2.charAt(i)) {
            break;
        }
    }
    if (i < cs2.length() || i < cs1.length()) {
        return i;
    }
    return INDEX_NOT_FOUND;
}

---

From source file:bfile.util.StringUtils.java

/**
 * <p>Counts how many times the char appears in the given string.</p>
 *
 * <p>A {@code null} or empty ("") String input returns {@code 0}.</p>
 *
 * <pre>//from  w  w w .  j av a  2 s  .  c om
 * StringUtils.countMatches(null, *)       = 0
 * StringUtils.countMatches("", *)         = 0
 * StringUtils.countMatches("abba", 0)  = 0
 * StringUtils.countMatches("abba", 'a')   = 2
 * StringUtils.countMatches("abba", 'b')  = 2
 * StringUtils.countMatches("abba", 'x') = 0
 * </pre>
 *
 * @param str  the CharSequence to check, may be null
 * @param ch  the char to count
 * @return the number of occurrences, 0 if the CharSequence is {@code null}
 * @since 3.4
 */
public static int countMatches(final CharSequence str, final char ch) {
    if (isEmpty(str)) {
        return 0;
    }
    int count = 0;
    // We could also call str.toCharArray() for faster look ups but that would generate more garbage.
    for (int i = 0; i < str.length(); i++) {
        if (ch == str.charAt(i)) {
            count++;
        }
    }
    return count;
}

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