CODEWITHSUNDEEP
javastringquote
Rattlesnake
Rattlesnake

Reputation: 143

Quote signs in strings (java)

I write a bracket checker in Java and have problems searching for single quotes in the text. if I have a String like e.g. the following (!in this case it's the text I'm interested not the code):

else if (line.charAt(i)=='\''||line.charAt(i)=='\"'){

in the debugger I see that after the first equals sign I get the following characters in my String:

0 = '

1 = \\\

2 = ' 

3 = '

How can I combine 1 and 2 - so that he doesn't read the second ' as ' anymore? I thought it is done with backslash - but obviously I'm doing something wrong.

If the code is of any help: This is how I treat single and double quotes:

Stack <Character> theStack = new Stack<Character>();
// loop through file line per line
String line;

else if (line.charAt(i)=='\'' ||line.charAt(i)=='\"'){
   // check whether there is already one of them on top
   if (line.charAt(i)== '\'' && theStack.peek()=='\''){
       theStack.pop();
    }

    else if (line.charAt(i)== '\"' && theStack.peek()=='\"'){
       theStack.pop();
    }
    // else push new one on top
    else {
        theStack.push(line.charAt(i));
    }
}

It fails because in the line shown above it reads three single/double quotes. It should read only two of them. I do not understand how I can avoid the Scanner to read the second single/double quote in the statement shown above as a single quote. I thought it is done with backslash.

Upvotes: 0

Views: 983

Answers (1)

Ravi K Thapliyal
Ravi K Thapliyal

Reputation: 51711

Just modify your if condition as follows

else if ((line.charAt(i) == '\'' || line.charAt(i) == '\"')
                               && line.charAt(i-1) != '\\') {

This would ignore all quotes that have been escaped with a backslash i.e. should not be treated as a closing quote and pop your character stack. You can further simplify your if-else blocks as

// check whether there is already one of them on top
if (line.charAt(i) == theStack.peek()) { // un-boxing to char
   theStack.pop();
}
// else push new one on top
else {
    theStack.push(line.charAt(i));
}

This works because the parent else-if block has already made sure that the line character is either ' or " and so we can go ahead and directly compare it with the head of your character stack.

Upvotes: 1

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