Develop Reference

How to use regex with String.split()

I have the following String:
String fullPDFContex = "Title1 Title2\r\nTitle3 Title4\r\n\r\nTitle5 Title6\r\n \r\n Title7 \r\n\r\n\r\n\r\n\r\n"
I want to convert it to an array of String which will look like this.
String[] Title = {"Title1 Title2","Title3 Title4","Title5 Title6","Title7"}
I am trying the following code.
String[] Title=fullPDFContext.split("\r\n\r\n|\r\n \r\n|\r\n");
But not getting the desired output.

You need to split with a pattern that matches any amount of whitespace that contains a line break:
String fullPDFContex = "Title1 Title2\r\nTitle3 Title4\r\n\r\nTitle5 Title6\r\n \r\n Title7 \r\n\r\n\r\n\r\n\r\n";
String separator = "\\p{javaWhitespace}*\\R\\p{javaWhitespace}*";
String results[] = fullPDFContex.split(separator);
System.out.println(Arrays.toString(results));
// => [Title1 Title2, Title3 Title4, Title5 Title6, Title7]
See the Java demo.
The \\p{javaWhitespace}*\\R\\p{javaWhitespace}* matches
\\p{javaWhitespace}* - 0+ whitespaces
\\R - a line break (you may replace it with [\r\n] for Java 7 and older)
\\p{javaWhitespace}* - 0+ whitespaces.
Alternatively, you may use a bit more efficient
String separator = "[\\s&&[^\r\n]]*\\R\\s*";
See another demo
Unfortunately, the \R construct cannot be used in the character classes. The pattern will match:
[\\s&&[^\r\n]]* - zero or more whitespace chars other than CR and LF (character class subtraction is used here)
\\R - a line break
\\s* - any 0+ whitespace chars.

Here is your solution. we can use StringTokenizer & I have used list to insert the splitted values.This can help you if you have n number of values splitted from your array
package com.sujit;
import java.util.ArrayList;
import java.util.List;
import java.util.StringTokenizer;
public class UserInput {
public static void main(String[] args) {
String fullPDFContex = "Title1 Title2\r\nTitle3 Title4\r\n\r\nTitle5 Title6\r\n \r\n Title7 \r\n\r\n\r\n\r\n\r\n";
StringTokenizer token = new StringTokenizer(fullPDFContex, "\r\n");
List<String> list = new ArrayList<>();
while (token.hasMoreTokens()) {
list.add(token.nextToken());
}
for (String string : list) {
System.out.println(string);
}
}
}

With this code you get the output you want:
String[] Title = fullPDFContext.split(" *(\r\n ?)+ *");

Regex split not working

I want split my string using regex.
String Str = " Dřevo5068Hlína5064Železo5064Obilí4895";
String reg = "(\\D+)(\\d+)(\\D+)(\\d+)(\\D+)(\\d+)(\\D+)(\\d+)";
if (Str.matches(reg)) {
String[] l = Str.split(reg);
System.out.println(Arrays.toString(l));
}
But, output is []. Where is problem?
Edit: I want split to:
Dřevo
5068
Hlína
5064
Železo
5064
Obilí
4895
Then I want get numbers from this String.

if your engine permits look-around, split using this pattern
(?<=\D)(?=\d)|(?<=\d)(?=\D)
Demo

How to split a string into two parts on specific delimeter

I have a string "Rush to ER/F07^e80c801e-ee37-4af8-9f12-af2d0e58e341".
I want to split it into 2 strings on the delimiter ^. For example string str1=Rush to ER/F07 and String str2 = e80c801e-ee37-4af8-9f12-af2d0e58e341
For getting this i am doing splitting of the string , I followed the tutorial on stackoverflow but it is not working for me , here is a code
String[] str_array = message.split("^");
String stringa = str_array[0];
String stringb = str_array[1];
when I am printing these 2 strings I am getting nothing in stringa and in stringb I am getting all the string as it was before the delimiter.
Please help me

You have to escape special regex sign via \\ try this:
String[] str_array = message.split("\\^");

It is because the .split() method requires a regex pattern. Escape the ^:
String[] str_array = message.split("\\^");
You can get more information on this at http://docs.oracle.com/javase/8/docs/api/java/lang/String.html#split-java.lang.String-.

Removing leading NewLine chars from String by regex?

I am new to "REGEX".And this question is training and educational for regex in java.
I try to remove leading new line chars from a string.(I know we can do this by 'trim()',but I do not want use it).I use '^[\r\n]+' as regex,like this:
str = "\r\n\r\ntest";
str.replaceAll("^[\r\n]+", "");
System.out.print(str);
I guess result will be
test
But the result is:
CRLF
CRLF
test
As you can see,leading new line chars do not removed.Also I try '^\s' or '^\s+' as regex,but result was same.Do you know why those regexes do not match leading new line chars?

A String cannot be modified: replaceAll returns the changed string.
str = str.replaceAll(...);

Java replaceAll escape characters into double escape

I have a string value which received from input field.
String searchingText = getText();
After i receive a string i search this string. But if string contains \ symbol my search is failed.
I know about special characters and try to replace :
searchingText = searchingText.replaceAll("\\","\\\\");
But it give me error and app was shutdown.
Exception in thread "main" java.util.regex.PatternSyntaxException: Unexpected internal error near index 1
After research i founded a regex and try to replace with matcher :
Map<String,String> sub = new HashMap<String,String>();
sub.put("\n", "\\\\n");
sub.put("\r", "\\\\r");
sub.put("\t", "\\\\t");
StringBuffer result = new StringBuffer();
Pattern regex = Pattern.compile("\\n|\\r|\\t");
Matcher matcher = regex.matcher(bodySearchText);
In the end i will want to get a string - searchingText = \\ instead of searchingText = \
Please any solutions.

You should do:
string = string.replaceAll("\\\\", "\\\\\\\\");
Note that in Java, \ is written as \\. So replaceAll will see \\ as \, which is not what you want.
Instead, you can use replace that accepts String and not a regex.

change this
searchingText = searchingText.replaceAll("\\","\\\\");
to
searchingText = searchingText.replaceAll("\\\\","\\\\\\");
the replaceAll() will take \\ as \ .
for more details read here