Java examples for java.lang:String Substring
Gets len characters from the middle of a String. If len characters are not available, the remainder of the String will be returned without an exception.
/*//from w w w . j a va 2 s . c o m * Copyright 2013 Guidewire Software, Inc. */ /** * This class is based, in part, on org.apache.commons.lang.StringUtils and is intended * to break the dependency on that project. * * @author <a href="http://jakarta.apache.org/turbine/">Apache Jakarta Turbine</a> * @author <a href="mailto:jon@latchkey.com">Jon S. Stevens</a> * @author Daniel L. Rall * @author <a href="mailto:gcoladonato@yahoo.com">Greg Coladonato</a> * @author <a href="mailto:ed@apache.org">Ed Korthof</a> * @author <a href="mailto:rand_mcneely@yahoo.com">Rand McNeely</a> * @author Stephen Colebourne * @author <a href="mailto:fredrik@westermarck.com">Fredrik Westermarck</a> * @author Holger Krauth * @author <a href="mailto:alex@purpletech.com">Alexander Day Chaffee</a> * @author <a href="mailto:hps@intermeta.de">Henning P. Schmiedehausen</a> * @author Arun Mammen Thomas * @author Gary Gregory * @author Phil Steitz * @author Al Chou * @author Michael Davey * @author Reuben Sivan * @author Chris Hyzer * Johnson */ //package com.java2s; public class Main { public static void main(String[] argv) { String str = "java2s.com"; int pos = 42; int len = 42; System.out.println(mid(str, pos, len)); } /** * The empty String <code>""</code>. * @since 2.0 */ public static final String EMPTY = ""; /** * <p>Gets <code>len</code> characters from the middle of a String.</p> * * <p>If <code>len</code> characters are not available, the remainder * of the String will be returned without an exception. If the * String is <code>null</code>, <code>null</code> will be returned. * An exception is thrown if len is negative.</p> * * <pre> * mid(null, *, *) = null * mid(*, *, -ve) = "" * mid("", 0, *) = "" * mid("abc", 0, 2) = "ab" * mid("abc", 0, 4) = "abc" * mid("abc", 2, 4) = "c" * mid("abc", 4, 2) = "" * mid("abc", -2, 2) = "ab" * </pre> * * @param str the String to get the characters from, may be null * @param pos the position to start from, negative treated as zero * @param len the length of the required String, must be zero or positive * @return the middle characters, <code>null</code> if null String input */ public static String mid(String str, int pos, int len) { if (str == null) { return null; } if (len < 0 || pos > str.length()) { return EMPTY; } if (pos < 0) { pos = 0; } if (str.length() <= (pos + len)) { return str.substring(pos); } return str.substring(pos, pos + len); } /** * Gets a String's length or <code>0</code> if the String is <code>null</code>. * * @param str * a String or <code>null</code> * @return String length or <code>0</code> if the String is <code>null</code>. * @since 2.4 */ public static int length(String str) { return str == null ? 0 : str.length(); } /** * <p>Gets a substring from the specified String avoiding exceptions.</p> * * <p>A negative start position can be used to start <code>n</code> * characters from the end of the String.</p> * * <p>A <code>null</code> String will return <code>null</code>. * An empty ("") String will return "".</p> * * <pre> * substring(null, *) = null * substring("", *) = "" * substring("abc", 0) = "abc" * substring("abc", 2) = "c" * substring("abc", 4) = "" * substring("abc", -2) = "bc" * substring("abc", -4) = "abc" * </pre> * * @param str the String to get the substring from, may be null * @param start the position to start from, negative means * count back from the end of the String by this many characters * @return substring from start position, <code>null</code> if null String input */ public static String substring(String str, int start) { if (str == null) { return null; } // handle negatives, which means last n characters if (start < 0) { start = str.length() + start; // remember start is negative } if (start < 0) { start = 0; } if (start > str.length()) { return EMPTY; } return str.substring(start); } /** * <p>Gets a substring from the specified String avoiding exceptions.</p> * * <p>A negative start position can be used to start/end <code>n</code> * characters from the end of the String.</p> * * <p>The returned substring starts with the character in the <code>start</code> * position and ends before the <code>end</code> position. All position counting is * zero-based -- i.e., to start at the beginning of the string use * <code>start = 0</code>. Negative start and end positions can be used to * specify offsets relative to the end of the String.</p> * * <p>If <code>start</code> is not strictly to the left of <code>end</code>, "" * is returned.</p> * * <pre> * substring(null, *, *) = null * substring("", * , *) = ""; * substring("abc", 0, 2) = "ab" * substring("abc", 2, 0) = "" * substring("abc", 2, 4) = "c" * substring("abc", 4, 6) = "" * substring("abc", 2, 2) = "" * substring("abc", -2, -1) = "b" * substring("abc", -4, 2) = "ab" * </pre> * * @param str the String to get the substring from, may be null * @param start the position to start from, negative means * count back from the end of the String by this many characters * @param end the position to end at (exclusive), negative means * count back from the end of the String by this many characters * @return substring from start position to end positon, * <code>null</code> if null String input */ public static String substring(String str, int start, int end) { if (str == null) { return null; } // handle negatives if (end < 0) { end = str.length() + end; // remember end is negative } if (start < 0) { start = str.length() + start; // remember start is negative } // check length next if (end > str.length()) { end = str.length(); } // if start is greater than end, return "" if (start > end) { return EMPTY; } if (start < 0) { start = 0; } if (end < 0) { end = 0; } return str.substring(start, end); } }