Java: method to get position of a match in a Strin

Question

String match = "hello";
String text = "0123456789hello0123456789";

int position = getPosition(match, text); // should be 10, is there such a method?

Answer 1

You can get all matches in a file simply by assigning inside while-loop, cool:

$ javac MatchTest.java 
$ java MatchTest 
1
16
31
46
$ cat MatchTest.java 
import java.util.*;
import java.io.*;

public class MatchTest {
    public static void main(String[] args){
        String match = "hello";
        String text = "hello0123456789hello0123456789hello1234567890hello3423243423232";
        int i =0;
        while((i=(text.indexOf(match,i)+1))>0)
            System.out.println(i);
    }
}

Answer 2

I have some big code but working nicely....

   class strDemo
   { 
       public static void main(String args[])
       {
       String s1=new String("The Ghost of The Arabean Sea");
           String s2=new String ("The");
           String s6=new String ("ehT");
           StringBuffer s3;
           StringBuffer s4=new StringBuffer(s1);
           StringBuffer s5=new StringBuffer(s2);
           char c1[]=new char[30];
           char c2[]=new char[5];
           char c3[]=new char[5];
           s1.getChars(0,28,c1,0);
           s2.getChars(0,3,c2,0);
           s6.getChars(0,3,c3,0); s3=s4.reverse();      
           int pf=0,pl=0;
           char c5[]=new char[30];
           s3.getChars(0,28,c5,0);
           for(int i=0;i<(s1.length()-s2.length());i++)
           {
               int j=0;
               if(pf<=1)
               {
                  while (c1[i+j]==c2[j] && j<=s2.length())
                  {           
                    j++;
                    System.out.println(s2.length()+" "+j);
                    if(j>=s2.length())
                    {
                       System.out.println("first match of(The) :->"+i);

                     }
                     pf=pf+1;         
                  }   
             }                
       }       
         for(int i=0;i<(s3.length()-s6.length()+1);i++)
        {
            int j=0;
            if(pl<=1)
            {
             while (c5[i+j]==c3[j] && j<=s6.length())
             {
                 j++;
                 System.out.println(s6.length()+" "+j);
                 if(j>=s6.length())
                 {
                         System.out.println((s3.length()-i-3));
                         pl=pl+1;

                 }   
                }                 
              }  
           }  
         }
       }

Answer 3

//finding a particular word any where inthe string and printing its index and occurence  
class IndOc
{
    public static void main(String[] args) 
    {
        String s="this is hyderabad city and this is";
        System.out.println("the given string is ");
        System.out.println("----------"+s);
        char ch[]=s.toCharArray();
        System.out.println(" ----word is found at ");
        int j=0,noc=0;
        for(int i=0;i<ch.length;i++)
        {
            j=i;

            if(ch[i]=='i' && ch[j+1]=='s')
            {
                System.out.println(" index "+i);
            noc++;  
            }

        }
        System.out.println("----- no of occurences are "+noc);

    }
}

Answer 4

The family of methods that does this are:

• int indexOf(String str)
  • indexOf(String str, int fromIndex)
• int lastIndexOf(String str)
  • lastIndexOf(String str, int fromIndex)

Returns the index within this string of the first (or last) occurrence of the specified substring [searching forward (or backward) starting at the specified index].

---

String text = "0123hello9012hello8901hello7890";
String word = "hello";

System.out.println(text.indexOf(word)); // prints "4"
System.out.println(text.lastIndexOf(word)); // prints "22"

// find all occurrences forward
for (int i = -1; (i = text.indexOf(word, i + 1)) != -1; i++) {
    System.out.println(i);
} // prints "4", "13", "22"

// find all occurrences backward
for (int i = text.length(); (i = text.lastIndexOf(word, i - 1)) != -1; i++) {
    System.out.println(i);
} // prints "22", "13", "4"

Answer 5

This works using regex.

String text = "I love you so much";
String wordToFind = "love";
Pattern word = Pattern.compile(wordToFind);
Matcher match = word.matcher(text);

while (match.find()) {
     System.out.println("Found love at index "+ match.start() +" - "+ (match.end()-1));
}

Output :

Found 'love' at index 2 - 5

General Rule :

• Regex search left to right, and once the match characters has been used, it cannot be reused.

Answer 6

text.indexOf(match);

See the String javadoc