Java examples for java.lang:String New Line
get Index For Line Number
/*//from w w w .j a va2s . c om * 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 strSource = "java2s.com"; int iLine = 42; System.out.println(getIndexForLineNumber(strSource, iLine)); } public static int getIndexForLineNumber(String strSource, int iLine) { int iIndex = 0; for (int i = 1; i < iLine && iIndex != -1; i++) { iIndex = strSource.indexOf("\n", iIndex) + 1; } return iIndex; } /** * <p>Finds the first index within a String, handling <code>null</code>. * This method uses {@link String#indexOf(int)}.</p> * * <p>A <code>null</code> or empty ("") String will return <code>-1</code>.</p> * * <pre> * indexOf(null, *) = -1 * indexOf("", *) = -1 * indexOf("aabaabaa", 'a') = 0 * indexOf("aabaabaa", 'b') = 2 * </pre> * * @param str the String to check, may be null * @param searchChar the character to find * @return the first index of the search character, * -1 if no match or <code>null</code> string input * @since 2.0 */ public static int indexOf(String str, char searchChar) { if (isEmpty(str)) { return -1; } return str.indexOf(searchChar); } /** * <p>Finds the first index within a String from a start position, * handling <code>null</code>. * This method uses {@link String#indexOf(int, int)}.</p> * * <p>A <code>null</code> or empty ("") String will return <code>-1</code>. * A negative start position is treated as zero. * A start position greater than the string length returns <code>-1</code>.</p> * * <pre> * indexOf(null, *, *) = -1 * indexOf("", *, *) = -1 * indexOf("aabaabaa", 'b', 0) = 2 * indexOf("aabaabaa", 'b', 3) = 5 * indexOf("aabaabaa", 'b', 9) = -1 * indexOf("aabaabaa", 'b', -1) = 2 * </pre> * * @param str the String to check, may be null * @param searchChar the character to find * @param startPos the start position, negative treated as zero * @return the first index of the search character, * -1 if no match or <code>null</code> string input * @since 2.0 */ public static int indexOf(String str, char searchChar, int startPos) { if (isEmpty(str)) { return -1; } return str.indexOf(searchChar, startPos); } /** * <p>Finds the first index within a String, handling <code>null</code>. * This method uses {@link String#indexOf(String)}.</p> * * <p>A <code>null</code> String will return <code>-1</code>.</p> * * <pre> * indexOf(null, *) = -1 * indexOf(*, null) = -1 * indexOf("", "") = 0 * indexOf("aabaabaa", "a") = 0 * indexOf("aabaabaa", "b") = 2 * indexOf("aabaabaa", "ab") = 1 * indexOf("aabaabaa", "") = 0 * </pre> * * @param str the String to check, may be null * @param searchStr the String to find, may be null * @return the first index of the search String, * -1 if no match or <code>null</code> string input * @since 2.0 */ public static int indexOf(String str, String searchStr) { if (str == null || searchStr == null) { return -1; } return str.indexOf(searchStr); } /** * <p>Finds the first index within a String, handling <code>null</code>. * This method uses {@link String#indexOf(String, int)}.</p> * * <p>A <code>null</code> String will return <code>-1</code>. * A negative start position is treated as zero. * An empty ("") search String always matches. * A start position greater than the string length only matches * an empty search String.</p> * * <pre> * indexOf(null, *, *) = -1 * indexOf(*, null, *) = -1 * indexOf("", "", 0) = 0 * indexOf("aabaabaa", "a", 0) = 0 * indexOf("aabaabaa", "b", 0) = 2 * indexOf("aabaabaa", "ab", 0) = 1 * indexOf("aabaabaa", "b", 3) = 5 * indexOf("aabaabaa", "b", 9) = -1 * indexOf("aabaabaa", "b", -1) = 2 * indexOf("aabaabaa", "", 2) = 2 * indexOf("abc", "", 9) = 3 * </pre> * * @param str the String to check, may be null * @param searchStr the String to find, may be null * @param startPos the start position, negative treated as zero * @return the first index of the search String, * -1 if no match or <code>null</code> string input * @since 2.0 */ public static int indexOf(String str, String searchStr, int startPos) { if (str == null || searchStr == null) { return -1; } // JDK1.2/JDK1.3 have a bug, when startPos > str.length for "", hence if (searchStr.length() == 0 && startPos >= str.length()) { return str.length(); } return str.indexOf(searchStr, startPos); } /** * <p>Checks if a String is empty ("") or null.</p> * * <pre> * StringUtils.isEmpty(null) = true * StringUtils.isEmpty("") = true * StringUtils.isEmpty(" ") = false * StringUtils.isEmpty("bob") = false * StringUtils.isEmpty(" bob ") = false * </pre> * * <p>NOTE: This method changed in Lang version 2.0. * It no longer trims the String. * That functionality is available in isBlank().</p> * * @param str the String to check, may be null * @return <code>true</code> if the String is empty or null */ public static boolean isEmpty(String str) { return str == null || str.length() == 0; } /** * 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(); } }