Searching an String array for a sub-string?

I am trying to write a little method in java, but I cannot figure it out. What I want to be able to do is enter a string, and then the value of an int variable is set to the index of this in the array, i.e if I have an array consisting of

[0] 'hi guys'
[1] 'this'
[2] 'is'
[3] 'sparta'

The value of my integer is set at 0, and I want to find the first occurrence of "ta", which will be [3], so I want the function to set my integer to 3.

What I have a开发者_如何学Ct the moment is completely off the wall and wrong, is there any simple way of doing this ? I already have a function called get() defined which returns the value of the current line (i.e get(0) in this case would return 'hi guys'). Can anyone help me out please ?

Thanks a lot :)

 public void find(String line ) {
   boolean found = false;
   int i = cursor + 1;
   while ( found = false && i!=cursor) {
   if ((doc.get(cursor).indexOf( line ) > 0)){
  cursor = i;
  found = true;
   }else {
    cursor++;
    cursor%=doc.size();
    i++;

   }
 }
 }

Usually I dont do this, but today is Saturday and I am happy and probably going to get drunk

public void find(String line ) {
   boolean found = false;
   int i = 0;;
   while (i < doc.size()) {
     if ((doc.get(i).indexOf( line ) > 0)){
       cursor = i;
       found = true;
       break;
     }else {
       i++;
     }
   }
   if (found) {
      // print cursor or do whatever
   }
 }

You should note if this is homework.

One way to do this is:

    int i = 0;
    String searchTerm = "ta";

    System.out.println("Following substrings contain search term:");
    for (String s : "hi guys,this,is,sparta".split(",")) {
        if (s.contains(searchTerm)) System.out.println(i++);
        else i++;
    }

Or if you prefer using regex, then change s.contains(searchTerm) with s.matches(searchTerm).

If this is not homework, but interview question or work problem, this would be vastly more complex. For example: aminoacid sequence is search term and need to find locations in DNA/RNA where it is located. In that case you need more complex solution.

Examples:

• Brute-Force String Matching
• Suffix Trees String Matching Algorithm ( wiki )
• Boyer-Moore String Matching Algorithm ( wiki )
• Knuth-Morris-Pratt String Matching ( wiki )
• Sunday String Matching algorithm ( wiki )
• Horspool String Matching algorithm ( wiki )
• Rabin-Karp string matching algorithm ( wiki )
• Aho–Corasick string matching algorithm ( wiki )

If understood your task correctly, I would do something like:

public int find(String line, int startPosition) {
    if (doc[startPosition].contains(line) {
        return startPosition;
    }
    for (int i = 0; i < Math.max(doc.size() - startPosition, startPosition); i++) {
        if (startPosition - i > 0 && doc[startPosition - i].contains(line)) {
            return startPosition - i;
        }
        if (startPosition + i < doc.size() && doc[startPosition + i].contains(line)) {
            return startPosition + i;
        }

    }
    return -1;
}

This would return an index of the first element in the array that contains the substring passed as line parameter.

He says this is not homework, so here it is:

(this actually compiles and works)

    import java.io.*;

    public class A {
            public static void main(String[] args) {
                    String[] arr = {"hi guys", "this", "is", "sparta"};
                    System.out.println("enter substring:");
                    String substr = "";
                    try {
                    substr = new BufferedReader(new InputStreamReader(System.in)).readLine();
                    } catch(IOException e) {System.exit(0);}
                    for(int i =0; i<arr.length; i++) {
                            int charPos = arr[i].indexOf(substr);
                            if(charPos!=-1) {
                                    System.out.println("found in string index " + i + " at "+charPos);
                                    break;
                            }
                    }
            }
    }

would’t it be more sensible to search in the actual string[] instead of each line?

then you loop over the array and return the current index if the string at this position contains the substring.