Question

I am trying to make a recursive class that takes a string as a parameter and returns a line from a stringlist that starts with the parameter string. If it cant find a match, it should return “”. I seem to be almost there but for some reason once the string is found and enters the if statement, it returns the string, but then jumps to the other statement in the code. In other words, its not returning it for some reason. any help would really help.

public String getLineStartingWith(String _string){

    System.out.println("GETLINESTRING: " + _string);

    //place parameter string into local string
    String string = _string;

    //return the line from the stringlist if it starts with the 
    //parameter string

    if(currentString.startsWith(_string)){
        System.out.println("CURRENT STRING: " + currentString);
        return currentString;
    } 

    restOfList.getLineStartingWith(_string);
    return "";

    //return restOfList.getLineStartingWith(_string);
}

EDIT

I made some changes to my code. But for some reason, after it returns the current string, it returns restOfList.getLineStartingWith(string) everytime. I think its not detecting if its empty or not

public String getLineStartingWith(String string){

    System.out.println("GETLINESTRING: " + string);

    //return the line from the stringlist if it starts with the 
    //parameter string

    if(currentString.startsWith(string)){
       System.out.println("CURRENT STRING: " + currentString);
       return currentString;
    } 

    if(restOfList.isEmpty){
        return "";
    }

    return restOfList.getLineStartingWith(string);
}

Answer 1

Why are you doing this?

//place parameter string into local string
String string = _string;

This code has exactly the same effect:

public String getLineStartingWith(String string){

    System.out.println("GETLINESTRING: " + string);
    // etc.

String are immutable, so you can’t do anything bad to the input. Also, you’re not even using string (all of your later code uses _string).

I think your problem is that this isn’t being returned:

restOfList.getLineStartingWith(_string);

Try:

return restOfList.getLineStartingWith(_string);

You probably also need another base-case that handles restOfList being empty.