Regular expression to find strings beginning with a particular digit

[neha_sinha]

hello everyone,

i am trying to match data by using regular expression.For eg if a user enters 1*
then he should get all the ip address that start with 1
1.23.56.89
123.56.90.67
(note:ip address validation need not be taken care of since data is matched against valid ip addresses)

the pattern that i am providing is
1\d*\.\d+\.\d+\.\d+

but the problem is am not getting the correct answer...the matched answers that am getting are:
201.56.78.90
172.23.45.67
172.34.87.90

                                         text1=cmb1_1[0].getSelectedItem().toString();
                                        int count1=0;
					for(i=0;i<text1.length();i++)
					{
						if(text1.charAt(i)=='.')
						{
							
						
							count1++;
					}
					}

                                        if(count1==0)
					{
						if(text1.charAt(1)=='*')
						{
							text1.replace("*","@");
							text1=text1+".*"+".*"+".*";
						}
					}

					 for(i=0;i<text1.length();i++)
						{
							
							text1.replace(".","\\.");
							text1.replace("*","\\d+");
						}
						
							
							
							text1.replaceAll("@","\\d*");
							
                                                Pattern pattern=Pattern.compile(text1);
                              Matcher   matcher=pattern.matcher(rowValue);  
                              if(matcher.matches())
        			System.out.println("matched"+rowValue);

please help me with this..what pattern should i give to search all strings that begin with a particular digit.

thanks

[JosAH]

Try to make it search/match from the start of the String; e.g. "^1\d*\.\d+\.\d+\.\d+"

b.t.w. what does this have to do with Swing?

kind regards,

Jos

[neha_sinha]

thanks for replying...and sorry i do realise that it has nothing to do with swing...i tried out what you suggested but its only working for me if i create the pattern statically assuming that the user will search for only strings beginning with 1

Pattern pattern=Pattern.compile("^1\\d*\\.\\d+\\.\\d+\\.\\ d+");

but if i try to make it dynamic and try appending '^' before the string its not working for me

                                         if(count1==0)
					{
						if(text1.charAt(1)=='*')
						{
							text1.replace("*","@");
						[QUOTE]
                                                   text1="^"+text1+".*"+".*"+".*";	           

                                              [/QUOTE]
						}
					}

                                           for(i=0;i<text1.length();i++)
						{
							
							text1.replace(".","\\.");
							text1.replace("*","\\d+");
						}
						
							
							
							text1.replaceAll("@","\\d*");
							System.out.println(text1);
							
							
        		 Pattern pattern=Pattern.compile(text1);

its again giving the incorrect answer(i.e. including 201.56.78.90 also)...why appending '^' to the string is not working....

thanks.

[JosAH]

its again giving the incorrect answer(i.e. including 201.56.78.90 also)...why appending '^' to the string is not working....

Print the resulting regular expression 'text1' before you compile and apply it; show us the result.

kind regards,

Jos

[neha_sinha]

thanks for replying again

before Pattern.compile statement the value that text1 contains is:
^1*.*.*.*

am posting a short snippet...you can run it and see..

import java.util.regex.Matcher;
import java.util.regex.Pattern;


public class testStringFunctionality {
	
	public static void main(String args[])
	{
		String string="1*";
		
		int count1=0;
		for(int i=0;i<string.length();i++)
		{
			if(string.charAt(i)=='.')
				count1++;
		}
		
		if(count1==0)
		{
			
			if(string.charAt(1)=='*')
			{
				string.replace("*","@");
				string="^"+string+".*"+".*"+".*";
			}
			
		}
		
		
		for(int i=0;i<string.length();i++)
		{
			string.replace(".","\\.");
		    string.replace("*","\\d+");
		}
		 System.out.println(string);
	       string.replaceAll("@","\\d*");
			
			
			// Pattern pattern=Pattern.compile("^1\\d*\\.\\d+\\.\\d+\\.\\d+");
	      
	       Pattern pattern=Pattern.compile(string);
			 System.out.println(pattern);
			 
	        	 Matcher matcher=pattern.matcher("221.56.78.90");
	        			 
	        			 if(matcher.matches())
	        				 System.out.println("matched");
	        			 else
	        				 System.out.println("not matched");
	        				 
	        				
	        				 
	
	}

}

its again showing matched

[JosAH]

thanks for replying again

before Pattern.compile statement the value that text1 contains is:
^1*.*.*.*

That regular expression is not correct; it reads: match the start of the text (^) followed by zero or more '1' characters (1*) followed by zero or more 'anything' characters (.*) etc. etc.

kind regards,

Jos

[neha_sinha]

thanks...
could you please suggest what all changes do i need to make to the snippet to have the correct regular expression so that i can get the correct result..am stuck with it...I am replacing '.' by "\\." and '*' by "\\d+"...but still why its giving the wrong value...please do help..

thanks

[JosAH]

thanks...
could you please suggest what all changes do i need to make to the snippet to have the correct regular expression so that i can get the correct result..am stuck with it...I am replacing '.' by "\\." and '*' by "\\d+"...but still why its giving the wrong value...please do help..

thanks

So you are trying to transform something else to a (valid) regular expression? What is the syntax of that 'something else'?

kind regards,

Jos

[neha_sinha]

hey thanks for all your help...i debugged it myself...actually there was some problem with the implementation of replace method...its working correctly now...here's is the snippet :)

import java.util.regex.Matcher;
import java.util.regex.Pattern;


public class testStringFunctionality {
	
	public static void main(String args[])
	{
		
		 String string = "1*";
		
		
		
		
		int count1=0;
		for(int i=0;i<string.length();i++)
		{
			if(string.charAt(i)=='.')
				count1++;
		}
		
		if(count1==0)
		{
			
			if(string.charAt(1)=='*')
			{
				String expression = "*";
				 String replacement = "@";
			
				 string=string.replace(expression, replacement);
				string="^"+string+".*"+".*"+".*";
			}
			
		}
		
		
		
				 String expression = ".";
				 String replacement = "\\.";
			
				 string =string.replace(expression, replacement);
				
				 expression = "*";
				  replacement = "\\d+";
			
				 string=string.replace(expression, replacement);
				
			
		
		 expression = "@";
		  replacement = "\\d*";
	
		  string=string.replace(expression, replacement);
			
			
			
	      
	       Pattern pattern=Pattern.compile(string);
			 System.out.println(pattern);
			 

	        			 Matcher matcher=pattern.matcher("221.56.78.90");




	        			 
	        			 if(matcher.matches())
	        				 System.out.println("matched");
	        			 else
	        				 System.out.println("not matched");
	        				 
	        				
	        	
	
	}

}

thanks

[JosAH]

hey thanks for all your help...i debugged it myself...actually there was some problem with the implementation of replace method...its working correctly now...here's is the snippet :)
[ snip ]
thanks

You're welcome of course, glad you fixed it yourself. I didn't read all that code so all I can do is believe your claim about its correctness ;-)

kind regards,

Jos