package com.cloudhopper.commons.util;
/*
* #%L
* ch-commons-util
* %%
* Copyright (C) 2012 Cloudhopper by Twitter
* %%
* Licensed 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.
* #L%
*/
import java.io.IOException;
import java.io.InputStream;
import java.util.Locale;
import java.util.Properties;
import java.util.StringTokenizer;
/**
* A set of String utilities.
*
* @author joelauer (twitter: @jjlauer or <a href="http://twitter.com/jjlauer" target=window>http://twitter.com/jjlauer</a>)
*/
public class StringUtil {
private static final String PRINTABLE = ": ~`!@#$%^&*()-_+=/\\,.[]{}|?<>\"'";
private static final String SAFE = ":~!@#$%^&*()-_+=/\\,.[]{}|?<>";
// (gt, lt, quot, amp, apos) and then newline, carriage return
private static final String[][] XML_CHARS = {
{ "&", "&"},
{ "<", "<"},
{ ">", ">"},
{ "\"", """},
{ "'", "'"},
{ "\n", "
"},
{ "\r", "
"},
};
/**
* Searches the string for occurrences of the pattern $ENV{key} and
* attempts to replace this pattern with a value from the System environment
* obtained using the 'key'. For example, including "$ENV{USERNAME}" in
* a string and calling this method would then attempt to replace the entire
* pattern with the value of the environment variable "USERNAME". The System
* environment is obtained in Java with a call to System.getenv(). An environment variable is typically
* defined in the Linux shell or Windows property tabs. NOTE: A Java System
* property is not the same as an environment variable.
* @param string0 The string to perform substitution on such as "Hello $ENV{USERNAME}".
* This string may be null, empty, or contain one or more substitutions.
* @return A string with all occurrences of keys substituted with their
* values obtained from the System environment. Can be null if the
* original string was null.
* @throws SubstitutionException Thrown if a starting string was found, but the
* ending string was not. Also, thrown if a key value was empty such
* as using "$ENV{}". Finally, thrown if the property key was not
* found in the properties object (could not be replaced).
* @see #substituteWithProperties(java.lang.String, java.lang.String, java.lang.String, java.util.Properties)
*/
public static String substituteWithEnvironment(String string0) throws SubstitutionException {
// turn environment into properties
Properties envProps = new Properties();
// add all system environment vars to the properties
envProps.putAll(System.getenv());
// delegate to other method using the default syntax $ENV{<key>}
return substituteWithProperties(string0, "$ENV{", "}", envProps);
}
/**
* Searches string for occurrences of a pattern, extracts out a key name
* between the startStr and endStr tokens, then attempts to replace the
* property value into the string. This method is useful for merging
* property values into configuration strings/settings. For examle, the
* system environment Map could be converted into a Properties object then
* have its values merged into a String so that users can access environment
* variables.
* @param string0 The string to perform substitution on such as "Hello $ENV{TEST}".
* This string may be null, empty, or contain one or more substitutions.
* @param startStr The string that marks the start of a replacement key such
* as "$ENV{" if the final search pattern you wanted was "$ENV{<key>}".
* @param endStr The string that marks the end of a replacement key such
* as "}" if the final search pattern you wanted was "$ENV{<key>}".
* @param properties The property keys and associated values to use for
* replacement.
* @return A string with all occurrences of keys substituted with their
* values obtained from the properties object. Can be null if the
* original string was null.
* @throws SubstitutionException Thrown if a starting string was found, but the
* ending string was not. Also, thrown if a key value was empty such
* as using "$ENV{}". Finally, thrown if the property key was not
* found in the properties object (could not be replaced).
* @see #substituteWithEnvironment(java.lang.String)
*/
public static String substituteWithProperties(String string0, String startStr, String endStr, Properties properties) throws SubstitutionException {
// a null source string will always return the same -- a null result
if (string0 == null) {
return null;
}
// create a builder for the resulting string
StringBuilder result = new StringBuilder(string0.length());
// attempt to find the first occurrence of the starting string
int end = -1;
int pos = string0.indexOf(startStr);
// keep looping while we keep finding more occurrences
while (pos >= 0) {
// is there string data before the position that we should append to the result?
if (pos > end+1) {
result.append(string0.substring(end+endStr.length(), pos));
}
// search for endStr starting from the end of the startStr
end = string0.indexOf(endStr, pos+startStr.length());
// was the end found?
if (end < 0) {
throw new SubstitutionException("End of substitution pattern '" + endStr + "' not found [@position=" + pos + "]");
}
// extract the part in the middle of the start and end strings
String key = string0.substring(pos+startStr.length(), end);
// NOTE: don't trim the key, whitespace technically matters...
// was there anything left?
if (key == null || key.equals("")) {
throw new SubstitutionException("Property key was empty in string with an occurrence of '" + startStr + endStr + "' [@position=" + pos + "]");
}
// attempt to get this property
String value = properties.getProperty(key);
// was the property found
if (value == null) {
throw new SubstitutionException("A property value for '" + startStr + key + endStr + "' was not found (property missing?)");
}
// append this value to our result
result.append(value);
// find next occurrence after last end
pos = string0.indexOf(startStr, end+endStr.length());
}
// is there any string data we missed in the loop above?
if (end+endStr.length() < string0.length()) {
// append the remaining part of the string
result.append(string0.substring(end+endStr.length()));
}
return result.toString();
}
/**
* Returns true if the String is considered a "safe" string where only specific
* characters are allowed to be used. Useful for checking passwords or other
* information you don't want a user to be able to type just anything in.
* This method does not allow any whitespace characters, newlines, carriage returns.
* Primarily allows [a-z] [A-Z] [0-9] and a few other useful ASCII characters
* such as ":~!@#$%^*()-_+=/\\,.[]{}|?<>" (but not the quote chars)
*/
public static boolean isSafeString(String string0) {
for (int i = 0; i < string0.length(); i++) {
if (!isSafeChar(string0.charAt(i))) {
return false;
}
}
return true;
}
/**
* Returns true if the char is considered a "safe" char. Please see
* documentation for isSafeString().
* @see #isSafeString(java.lang.String)
*/
public static boolean isSafeChar(char ch) {
if (ch >= 'a' && ch <= 'z')
return true;
if (ch >= 'A' && ch <= 'Z')
return true;
if (ch >= '0' && ch <= '9')
return true;
// loop thru our PRINTABLE string
for (int i = 0; i < SAFE.length(); i++) {
if (ch == SAFE.charAt(i))
return true;
}
return false;
}
/**
* Safely capitalizes a string by converting the first character to upper
* case. Handles null, empty, and strings of length of 1 or greater. For
* example, this will convert "joe" to "Joe". If the string is null, this
* will return null. If the string is empty such as "", then it'll just
* return an empty string such as "".
* @param string0 The string to capitalize
* @return A new string with the first character converted to upper case
*/
static public String capitalize(String string0) {
if (string0 == null) {
return null;
}
int length = string0.length();
// if empty string, just return it
if (length == 0) {
return string0;
} else if (length == 1) {
return string0.toUpperCase();
} else {
StringBuilder buf = new StringBuilder(length);
buf.append(string0.substring(0, 1).toUpperCase());
buf.append(string0.substring(1));
return buf.toString();
}
}
/**
* Safely uncapitalizes a string by converting the first character to lower
* case. Handles null, empty, and strings of length of 1 or greater. For
* example, this will convert "Joe" to "joe". If the string is null, this
* will return null. If the string is empty such as "", then it'll just
* return an empty string such as "".
* @param string0 The string to uncapitalize
* @return A new string with the first character converted to lower case
*/
static public String uncapitalize(String string0) {
if (string0 == null) {
return null;
}
int length = string0.length();
// if empty string, just return it
if (length == 0) {
return string0;
} else if (length == 1) {
return string0.toLowerCase();
} else {
StringBuilder buf = new StringBuilder(length);
buf.append(string0.substring(0, 1).toLowerCase());
buf.append(string0.substring(1));
return buf.toString();
}
}
/**
* Checks if the targetString is contained within the array of strings. This
* method will return true if a "null" is contained in the array and the
* targetString is also null.
* @param strings The array of strings to search.
* @param targetString The string to search for
* @return True if the string is contained within, otherwise false. Also
* returns false if the strings array is null.
*/
static public boolean contains(String[] strings, String targetString) {
return (indexOf(strings, targetString) != -1);
}
/**
* Finds the first occurrence of the targetString in the array of strings.
* Returns -1 if an occurrence wasn't found. This
* method will return true if a "null" is contained in the array and the
* targetString is also null.
* @param strings The array of strings to search.
* @param targetString The string to search for
* @return The index of the first occurrence, or -1 if not found. If strings
* array is null, will return -1;
*/
static public int indexOf(String[] strings, String targetString) {
if (strings == null)
return -1;
for (int i = 0; i < strings.length; i++) {
if (strings[i] == null) {
if (targetString == null) {
return i;
}
} else {
if (targetString != null) {
if (strings[i].equals(targetString)) {
return i;
}
}
}
}
return -1;
}
/**
* If present, this method will strip off the leading and trailing "
* character in the string parameter. For example, "10958" will
* becomes just 10958.
*/
static public String stripQuotes(String string0) {
// if an empty string, return it
if (string0.length() == 0) {
return string0;
}
// if the first and last characters are quotes, just do 1 substring
if (string0.length() > 1 && string0.charAt(0) == '"' && string0.charAt(string0.length() - 1) == '"') {
return string0.substring(1, string0.length() - 1);
} else if (string0.charAt(0) == '"') {
string0 = string0.substring(1);
} else if (string0.charAt(string0.length() - 1) == '"') {
string0 = string0.substring(0, string0.length() - 1);
}
return string0;
}
/**
* Checks if a string contains only digits.
* @return True if the string0 only contains digits, or false otherwise.
*/
static public boolean containsOnlyDigits(String string0) {
// are they all digits?
for (int i = 0; i < string0.length(); i++) {
if (!Character.isDigit(string0.charAt(i))) {
return false;
}
}
return true;
}
/**
* Splits a string around matches of the given delimiter character.
*
* Where applicable, this method can be used as a substitute for
* <code>String.split(String regex)</code>, which is not available
* on a JSR169/Java ME platform.
*
* @param str the string to be split
* @param delim the delimiter
* @throws NullPointerException if str is null
*/
static public String[] split(String str, char delim) {
if (str == null) {
throw new NullPointerException("str can't be null");
}
// Note the javadoc on StringTokenizer:
// StringTokenizer is a legacy class that is retained for
// compatibility reasons although its use is discouraged in
// new code.
// In other words, if StringTokenizer is ever removed from the JDK,
// we need to have a look at String.split() (or java.util.regex)
// if it is supported on a JSR169/Java ME platform by then.
StringTokenizer st = new StringTokenizer(str, String.valueOf(delim));
int n = st.countTokens();
String[] s = new String[n];
for (int i = 0; i < n; i++) {
s[i] = st.nextToken();
}
return s;
}
/**
* Used to print out a string for error messages,
* chops is off at 60 chars for historical reasons.
*/
public final static String formatForPrint(String input) {
if (input.length() > 60) {
StringBuffer tmp = new StringBuffer(input.substring(0, 60));
tmp.append("&");
input = tmp.toString();
}
return input;
}
/**
* A method that receive an array of Objects and return a
* String array representation of that array.
*/
public static String[] toStringArray(Object[] objArray) {
int idx;
int len = objArray.length;
String[] strArray = new String[len];
for (idx = 0; idx < len; idx++) {
strArray[idx] = objArray[idx].toString();
}
return strArray;
}
/**
Get 7-bit ASCII character array from input String.
The lower 7 bits of each character in the input string is assumed to be
the ASCII character value.
Hexadecimal - Character
| 00 NUL| 01 SOH| 02 STX| 03 ETX| 04 EOT| 05 ENQ| 06 ACK| 07 BEL|
| 08 BS | 09 HT | 0A NL | 0B VT | 0C NP | 0D CR | 0E SO | 0F SI |
| 10 DLE| 11 DC1| 12 DC2| 13 DC3| 14 DC4| 15 NAK| 16 SYN| 17 ETB|
| 18 CAN| 19 EM | 1A SUB| 1B ESC| 1C FS | 1D GS | 1E RS | 1F US |
| 20 SP | 21 ! | 22 " | 23 # | 24 $ | 25 % | 26 & | 27 ' |
| 28 ( | 29 ) | 2A * | 2B + | 2C , | 2D - | 2E . | 2F / |
| 30 0 | 31 1 | 32 2 | 33 3 | 34 4 | 35 5 | 36 6 | 37 7 |
| 38 8 | 39 9 | 3A : | 3B ; | 3C < | 3D = | 3E > | 3F ? |
| 40 @ | 41 A | 42 B | 43 C | 44 D | 45 E | 46 F | 47 G |
| 48 H | 49 I | 4A J | 4B K | 4C L | 4D M | 4E N | 4F O |
| 50 P | 51 Q | 52 R | 53 S | 54 T | 55 U | 56 V | 57 W |
| 58 X | 59 Y | 5A Z | 5B [ | 5C \ | 5D ] | 5E ^ | 5F _ |
| 60 ` | 61 a | 62 b | 63 c | 64 d | 65 e | 66 f | 67 g |
| 68 h | 69 i | 6A j | 6B k | 6C l | 6D m | 6E n | 6F o |
| 70 p | 71 q | 72 r | 73 s | 74 t | 75 u | 76 v | 77 w |
| 78 x | 79 y | 7A z | 7B { | 7C | | 7D } | 7E ~ | 7F DEL|
*/
public static byte[] getAsciiBytes(String input) {
char[] c = input.toCharArray();
byte[] b = new byte[c.length];
for (int i = 0; i < c.length; i++) {
b[i] = (byte) (c[i] & 0x007F);
}
return b;
}
public static String getAsciiString(byte[] input) {
StringBuffer buf = new StringBuffer(input.length);
for (byte b : input) {
buf.append((char) b);
}
return buf.toString();
}
/**
* Trim off trailing blanks but not leading blanks
* @param str
* @return The input with trailing blanks stipped off
*/
public static String trimTrailing(String str) {
if (str == null) {
return null;
}
int len = str.length();
for (; len > 0; len--) {
if (!Character.isWhitespace(str.charAt(len - 1))) {
break;
}
}
return str.substring(0, len);
}
/**
Truncate a String to the given length with no warnings
or error raised if it is bigger.
@param value String to be truncated
@param length Maximum length of string
@return Returns value if value is null or value.length() is less or equal to than length, otherwise a String representing
value truncated to length.
*/
public static String truncate(String value, int length) {
if (value != null && value.length() > length) {
value = value.substring(0, length);
}
return value;
}
/**
* Return a slice (substring) of the passed in value, optionally trimmed.
* WARNING - endOffset is inclusive for historical reasons, unlike
* String.substring() which has an exclusive ending offset.
* @param value Value to slice, must be non-null.
* @param beginOffset Inclusive start character
* @param endOffset Inclusive end character
* @param trim To trim or not to trim
* @return Sliceed value.
*/
public static String slice(String value,
int beginOffset, int endOffset,
boolean trim) {
String retval = value.substring(beginOffset, endOffset + 1);
if (trim) {
retval = retval.trim();
}
return retval;
}
public static char[] HEX_TABLE = {
'0', '1', '2', '3', '4', '5', '6', '7', '8', '9',
'a', 'b', 'c', 'd', 'e', 'f'
};
/**
* @deprecated Please use new utility class HexUtil
* @see HexUtil#toHexString(byte[])
*/
@Deprecated
public static String toHexString(byte[] bytes) {
return HexUtil.toHexString(bytes);
}
/**
* @deprecated Please use new utility class HexUtil
* @see HexUtil#toHexString(byte[], int, int)
*/
@Deprecated
public static String toHexString(byte[] bytes, int offset, int length) {
return HexUtil.toHexString(bytes, offset, length);
}
/**
* @deprecated Please use new utility class HexUtil
* @see HexUtil#toByteArray(java.lang.CharSequence, int, int)
*/
@Deprecated
public static byte[] toHexByte(String hexString, int offset, int length) {
return HexUtil.toByteArray(hexString, offset, length);
}
/**
* Converts from a hex string like "FF" to a byte[].
* @param string0 The string containing the hex-encoded data.
* @return
* @deprecated Please use new utility class HexUtil
* @see HexUtil#toByteArray(java.lang.CharSequence)
*/
@Deprecated
public static byte[] fromHexString(String hexString) {
return HexUtil.toByteArray(hexString);
}
/**
* Convert a hexidecimal string generated by toHexString() back into a byte array.
* @param s String to convert
* @param offset starting character (zero based) to convert.
* @param length number of characters to convert.
* @return the converted byte array. Returns null if the length is not a multiple of 2.
* @deprecated Please use new utility class HexUtil
* @see HexUtil#toByteArray(java.lang.CharSequence, int, int)
*/
@Deprecated
public static byte[] fromHexString(String hexString, int offset, int length) {
return HexUtil.toByteArray(hexString, offset, length);
}
/**
* Return true if the character is printable in ASCII. Not using
* Character.isLetterOrDigit(); applies to all unicode ranges.
*/
public static boolean isPrintableChar(char ch) {
if (ch >= 'a' && ch <= 'z') {
return true;
}
if (ch >= 'A' && ch <= 'Z') {
return true;
}
if (ch >= '0' && ch <= '9') {
return true;
}
// loop thru our PRINTABLE string
for (int i = 0; i < PRINTABLE.length(); i++) {
if (ch == PRINTABLE.charAt(i)) {
return true;
}
}
return false;
}
/**
Convert a byte array to a human-readable String for debugging purposes.
*/
public static String hexDump(String prefix, byte[] data) {
byte byte_value;
StringBuffer str = new StringBuffer(data.length * 3);
str.append(prefix);
for (int i = 0; i < data.length; i += 16) {
// dump the header: 00000000:
String offset = Integer.toHexString(i);
// "0" left pad offset field so it is always 8 char's long.
str.append(" ");
for (int offlen = offset.length(); offlen < 8; offlen++) {
str.append("0");
}
str.append(offset);
str.append(":");
// dump hex version of 16 bytes per line.
for (int j = 0; (j < 16) && ((i + j) < data.length); j++) {
byte_value = data[i + j];
// add spaces between every 2 bytes.
if ((j % 2) == 0) {
str.append(" ");
}
// dump a single byte.
byte high_nibble = (byte) ((byte_value & 0xf0) >>> 4);
byte low_nibble = (byte) (byte_value & 0x0f);
str.append(HEX_TABLE[high_nibble]);
str.append(HEX_TABLE[low_nibble]);
}
// IF THIS IS THE LAST LINE OF HEX, THEN ADD THIS
if (i + 16 > data.length) {
// for debugging purposes, I want the last bytes always padded
// over so that the ascii portion is correctly positioned
int last_row_byte_count = data.length % 16;
int num_bytes_short = 16 - last_row_byte_count;
// number of spaces to add = (num bytes remaining * 2 spaces per byte) + (7 - (num bytes % 2))
int num_spaces = (num_bytes_short * 2) + (7 - (last_row_byte_count / 2));
for (int v = 0; v < num_spaces; v++) {
str.append(" ");
}
}
// dump ascii version of 16 bytes
str.append(" ");
for (int j = 0; (j < 16) && ((i + j) < data.length); j++) {
char char_value = (char) data[i + j];
// RESOLVE (really want isAscii() or isPrintable())
//if (Character.isLetterOrDigit(char_value))
if (isPrintableChar(char_value)) {
str.append(String.valueOf(char_value));
} else {
str.append(".");
}
}
// new line
str.append("\n");
}
// always trim off the last newline
str.deleteCharAt(str.length() - 1);
return (str.toString());
}
// The functions below are used for uppercasing SQL in a consistent manner.
// Derby will uppercase Turkish to the English locale to avoid i
// uppercasing to an uppercase dotted i. In future versions, all
// casing will be done in English. The result will be that we will get
// only the 1:1 mappings in
// http://www.unicode.org/Public/3.0-Update1/UnicodeData-3.0.1.txt
// and avoid the 1:n mappings in
//http://www.unicode.org/Public/3.0-Update1/SpecialCasing-3.txt
//
// Any SQL casing should use these functions
/** Convert string to uppercase
* Always use the java.util.ENGLISH locale
* @param s string to uppercase
* @return uppercased string
*/
public static String SQLToUpperCase(String s) {
return s.toUpperCase(Locale.ENGLISH);
}
/** Compares two strings
* Strings will be uppercased in english and compared
* equivalent to s1.equalsIgnoreCase(s2)
* throws NPE if s1 is null
*
* @param s1 first string to compare
* @param s2 second string to compare
*
* @return true if the two upppercased ENGLISH values are equal
* return false if s2 is null
*/
public static boolean SQLEqualsIgnoreCase(String s1, String s2) {
if (s2 == null) {
return false;
} else {
return SQLToUpperCase(s1).equals(SQLToUpperCase(s2));
}
}
/**
* Normalize a SQL identifer, up-casing if <regular identifer>,
* and handling of <delimited identifer> (SQL 2003, section 5.2).
* The normal form is used internally in Derby.
*
* @param id syntacically correct SQL identifier
*/
public static String normalizeSQLIdentifier(String id) {
if (id.length() == 0) {
return id;
}
if (id.charAt(0) == '"'
&& id.length() >= 3
&& id.charAt(id.length() - 1) == '"') {
// assume syntax is OK, thats is, any quotes inside are doubled:
return StringUtil.compressQuotes(
id.substring(1, id.length() - 1), "\"\"");
} else {
return StringUtil.SQLToUpperCase(id);
}
}
/**
* Compress 2 adjacent (single or double) quotes into a single (s or d)
* quote when found in the middle of a String.
*
* NOTE: """" or '''' will be compressed into "" or ''.
* This function assumes that the leading and trailing quote from a
* string or delimited identifier have already been removed.
* @param source string to be compressed
* @param quotes string containing two single or double quotes.
* @return String where quotes have been compressed
*/
public static String compressQuotes(String source, String quotes) {
String result = source;
int index;
/* Find the first occurrence of adjacent quotes. */
index = result.indexOf(quotes);
/* Replace each occurrence with a single quote and begin the
* search for the next occurrence from where we left off.
*/
while (index != -1) {
result = result.substring(0, index + 1)
+ result.substring(index + 2);
index = result.indexOf(quotes, index + 1);
}
return result;
}
/**
* Quote a string so that it can be used as an identifier or a string
* literal in SQL statements. Identifiers are surrounded by double quotes
* and string literals are surrounded by single quotes. If the string
* contains quote characters, they are escaped.
*
* @param source the string to quote
* @param quote the character to quote the string with (' or ")
* @return a string quoted with the specified quote character
* @see #quoteStringLiteral(String)
* @see IdUtil#normalToDelimited(String)
*/
static String quoteString(String source, char quote) {
// Normally, the quoted string is two characters longer than the source
// string (because of start quote and end quote).
StringBuffer quoted = new StringBuffer(source.length() + 2);
quoted.append(quote);
for (int i = 0; i < source.length(); i++) {
char c = source.charAt(i);
// if the character is a quote, escape it with an extra quote
if (c == quote) quoted.append(quote);
quoted.append(c);
}
quoted.append(quote);
return quoted.toString();
}
/**
* Quote a string so that it can be used as a string literal in an
* SQL statement.
*
* @param string the string to quote
* @return the string surrounded by single quotes and with proper escaping
* of any single quotes inside the string
*/
public static String quoteStringLiteral(String string) {
return quoteString(string, '\'');
}
/**
* Turn an array of ints into a printable string. Returns what's returned
* in Java 5 by java.util.Arrays.toString(int[]).
*/
public static String stringify(int[] raw) {
if (raw == null) {
return "null";
}
StringBuffer buffer = new StringBuffer();
int count = raw.length;
buffer.append("[ ");
for (int i = 0; i < count; i++) {
if (i > 0) {
buffer.append(", ");
}
buffer.append(raw[i]);
}
buffer.append(" ]");
return buffer.toString();
}
/**
* Checks if the string is an empty value which is true if the string is
* null or if the string represents an empty string of "". Please note that
* a string with just a space " " would not be considered empty.
* @param string0 The string to check
* @return True if null or "", otherwise false.
*/
public static boolean isEmpty(String string0) {
if (string0 == null || string0.length() == 0) {
return true;
} else {
return false;
}
}
public static boolean isEqual(String string0, String string1) {
return isEqual(string0, string1, true);
}
/**
* Returns the value from calling "toString()" on the object, but is a safe
* version that gracefully handles NULL objects by returning a String of "".
* @param obj The object to call toString() on. Safely handles a null object.
* @return The value from obj.toString() or "" if the object is null.
* @see #toStringWithNullAsNull(java.lang.Object)
*/
static public String toStringWithNullAsEmpty(Object obj) {
if (obj == null) {
return "";
} else {
return obj.toString();
}
}
/**
* Returns the value from calling "toString()" on the object, but is a safe
* version that gracefully handles NULL objects by returning a String of "<NULL>".
* @param obj The object to call toString() on. Safely handles a null object.
* @return The value from obj.toString() or "<NULL>" if the object is null.
* @see #toStringWithNullAsEmpty(java.lang.Object)
*/
static public String toStringWithNullAsReplaced(Object obj) {
if (obj == null) {
return "<NULL>";
} else {
return obj.toString();
}
}
/**
* Returns the value from calling "toString()" on the object, but is a safe
* version that gracefully handles NULL objects by returning null (rather
* than causing a NullPointerException).
* @param obj The object to call toString() on. Safely handles a null object.
* @return The value from obj.toString() or null if the object is null.
* @see #toStringWithNullAsEmpty(java.lang.Object)
*/
static public String toStringWithNullAsNull(Object obj) {
if (obj == null) {
return null;
} else {
return obj.toString();
}
}
/**
* Checks if both strings are equal to each other. Safely handles the case
* where either string may be null. The strings are evaluated as equal if
* they are both null or if they actually equal each other. One string
* that is null while the other one isn't (even if its an empty string) will
* be considered as NOT equal. Case sensitive comparisons are optional.
* @param string0 The string to compare
* @param string1 The other string to compare with
* @param caseSensitive If true a case sensitive comparison will be made,
* otherwise equalsIgnoreCase will be used.
* @return True if the strings are both null or equal to each other, otherwise
* false.
*/
public static boolean isEqual(String string0, String string1, boolean caseSensitive) {
if (string0 == null && string1 == null) {
return true;
}
if (string0 == null && string1 != null) {
return false;
}
if (string0 != null && string1 == null) {
return false;
}
if (caseSensitive) {
return string0.equals(string1);
} else {
return string0.equalsIgnoreCase(string1);
}
}
public static String readToString(InputStream in) throws IOException {
StringBuilder out = new StringBuilder();
byte[] b = new byte[4096];
for (int n; (n = in.read(b)) != -1;) {
out.append(new String(b, 0, n));
}
return out.toString();
}
/**
* Escapes the characters in a String using XML entities.
* For example: "bread" & "butter'ed" => "bread" & "butter'ed"
*
* Supports the five basic XML entities (gt, lt, quot, amp, apos) and also
* supports a newline and carriage return character. A newline is escaped
* to
and a carriage return to
*
* @param value The string to escape
* @return The escaped String that can be used in an XML document.
*/
public static String escapeXml(String value) {
// null to null
if (value == null)
return null;
// assume the resulting string will be the same
int len = value.length();
StringBuilder buf = new StringBuilder(len);
for (int i = 0; i < len; i++) {
char c = value.charAt(i);
boolean entityFound = false;
// is this a matching entity?
for (int j = 0; j < XML_CHARS.length; j++) {
// is this the matching character?
if (c == XML_CHARS[j][0].charAt(0)) {
// append the entity
buf.append(XML_CHARS[j][1]);
entityFound = true;
}
}
if (!entityFound) {
buf.append(c);
}
}
return buf.toString();
}
/**
* Removes all other characters from a string except digits. A good way
* of cleaing up something like a phone number.
* @param str0 The string to clean up
* @return A new String that has all characters except digits removed
*/
static public String removeAllCharsExceptDigits(String str0) {
if (str0 == null) {
return null;
}
if (str0.length() == 0) {
return str0;
}
StringBuilder buf = new StringBuilder(str0.length());
int length = str0.length();
for (int i = 0; i < length; i++) {
char c = str0.charAt(i);
if (Character.isDigit(c)) {
// append this character to our string
buf.append(c);
}
}
return buf.toString();
}
}