Java Tutorial/Data Type/String Start End
Содержание
Accessing String Characters
<source lang="java">
public class MainClass{
public static void main(String[] arg){
String str = "abcde";
System.out.println(str.charAt(2));
}
}</source>
c
Checking the End of a String
<source lang="java">
public class MainClass {
public static void main(String[] arg) {
String string1 = "abcde";
if(string1.endsWith("de")) {
System.out.println("ends with de");
}
}
}</source>
ends with de
Checking the Start of a String
<source lang="java">
public class MainClass {
public static void main(String[] arg) {
String string1 = "abcde";
if(string1.startsWith("ab")) {
System.out.println("starts with ab");
}
}
}</source>
starts with ab
Chop i characters off the end of a string.
<source lang="java">
/*
* Licensed to the Apache Software Foundation (ASF) under one * or more contributor license agreements. See the NOTICE file * distributed with this work for additional information * regarding copyright ownership. The ASF licenses this file * to you 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. */
import java.util.StringTokenizer;
/**
* * @author * @version $Id: StringUtils.java 685685 2008-08-13 21:43:27Z nbubna $ */
public class Main {
/**
* Line separator for the OS we are operating on.
*/
private static final String EOL = System.getProperty("line.separator");
/**
* Chop i characters off the end of a string.
* This method assumes that any EOL characters in String s
* and the platform EOL will be the same.
* A 2 character EOL will count as 1 character.
*
* @param s String to chop.
* @param i Number of characters to chop.
* @return String with processed answer.
*/
public static String chop(String s, int i)
{
return chop(s, i, EOL);
}
/**
* Chop i characters off the end of a string.
* A 2 character EOL will count as 1 character.
*
* @param s String to chop.
* @param i Number of characters to chop.
* @param eol A String representing the EOL (end of line).
* @return String with processed answer.
*/
public static String chop(String s, int i, String eol)
{
if ( i == 0 || s == null || eol == null )
{
return s;
}
int length = s.length();
/*
* if it is a 2 char EOL and the string ends with
* it, nip it off. The EOL in this case is treated like 1 character
*/
if ( eol.length() == 2 && s.endsWith(eol ))
{
length -= 2;
i -= 1;
}
if ( i > 0)
{
length -= i;
}
if ( length < 0)
{
length = 0;
}
return s.substring( 0, length);
}
}</source>
Removes separator from the end of str if it"s there, otherwise leave it alone.
<source lang="java">
import java.io.PrintWriter; import java.sql.Connection; import java.sql.SQLException; /*
* Licensed to the Apache Software Foundation (ASF) under one or more * contributor license agreements. See the NOTICE file distributed with * this work for additional information regarding copyright ownership. * The ASF licenses this file to You 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. * * */
public class Main {
/** * Removes*separatorfrom the end of *strif it"s there, otherwise leave it alone. * * NOTE: This method changed in version 2.0. * It now more closely matches Perl chomp. * For the previous behavior, use {@link #substringBeforeLast(String, String)}. * This method uses {@link String#endsWith(String)}. *
* StringUtils.chomp(null, *) = null
* StringUtils.chomp("", *) = ""
* StringUtils.chomp("foobar", "bar") = "foo"
* StringUtils.chomp("foobar", "baz") = "foobar"
* StringUtils.chomp("foo", "foo") = ""
* StringUtils.chomp("foo ", "foo") = "foo "
* StringUtils.chomp(" foo", "foo") = " "
* StringUtils.chomp("foo", "foooo") = "foo"
* StringUtils.chomp("foo", "") = "foo"
* StringUtils.chomp("foo", null) = "foo"
*
*
* @param str the String to chomp from, may be null
* @param separator separator String, may be null
* @return String without trailing separator, null if null String input
*/
public static String chomp(String str, String separator) {
if (isEmpty(str) || separator == null) {
return str;
}
if (str.endsWith(separator)) {
return str.substring(0, str.length() - separator.length());
}
return str;
}
// Empty checks
//-----------------------------------------------------------------------
/**
* Checks if a String is empty ("") or null.
*
*
* StringUtils.isEmpty(null) = true
* StringUtils.isEmpty("") = true
* StringUtils.isEmpty(" ") = false
* StringUtils.isEmpty("bob") = false
* StringUtils.isEmpty(" bob ") = false
*
*
* NOTE: This method changed in Lang version 2.0.
* It no longer trims the String.
* That functionality is available in isBlank().
*
* @param str the String to check, may be null
* @return true if the String is empty or null
*/
public static boolean isEmpty(String str) {
return str == null || str.length() == 0;
}
}</source>
Remove the last character from a String.
<source lang="java">
import java.io.PrintWriter; import java.sql.Connection; import java.sql.SQLException; /*
* Licensed to the Apache Software Foundation (ASF) under one or more * contributor license agreements. See the NOTICE file distributed with * this work for additional information regarding copyright ownership. * The ASF licenses this file to You 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. * * */
public class Main {
/** **\u000alinefeed LF ("\n"). * * @see * @since 2.2 */ public static final char CR = "\r"; // Chopping //----------------------------------------------------------------------- /** * Remove the last character from a String. * * If the String ends in\r\n, then remove both * of them. *
* StringUtils.chop(null) = null
* StringUtils.chop("") = ""
* StringUtils.chop("abc \r") = "abc "
* StringUtils.chop("abc\n") = "abc"
* StringUtils.chop("abc\r\n") = "abc"
* StringUtils.chop("abc") = "ab"
* StringUtils.chop("abc\nabc") = "abc\nab"
* StringUtils.chop("a") = ""
* StringUtils.chop("\r") = ""
* StringUtils.chop("\n") = ""
* StringUtils.chop("\r\n") = ""
*
*
* @param str the String to chop last character from, may be null
* @return String without last character, null if null String input
*/
public static String chop(String str) {
if (str == null) {
return null;
}
int strLen = str.length();
if (strLen < 2) {
return "";
}
int lastIdx = strLen - 1;
String ret = str.substring(0, lastIdx);
char last = str.charAt(lastIdx);
if (last == LF) {
if (ret.charAt(lastIdx - 1) == CR) {
return ret.substring(0, lastIdx - 1);
}
}
return ret;
}
// Empty checks
//-----------------------------------------------------------------------
/**
* Checks if a String is empty ("") or null.
*
*
* StringUtils.isEmpty(null) = true
* StringUtils.isEmpty("") = true
* StringUtils.isEmpty(" ") = false
* StringUtils.isEmpty("bob") = false
* StringUtils.isEmpty(" bob ") = false
*
*
* NOTE: This method changed in Lang version 2.0.
* It no longer trims the String.
* That functionality is available in isBlank().
*
* @param str the String to check, may be null
* @return true if the String is empty or null
*/
public static boolean isEmpty(String str) {
return str == null || str.length() == 0;
}
}</source>
