Loop Solution - Simplify Path

The idea is to divide by blocks and process each block like "/.."; a stack is defined to store temporary results, which is a String sequence, and some pop and push operations are involved in the logic.

Some edge conditions need to be careful and clarified.

public class Solution {
    public String simplifyPath(String path) {
        if(path == null || (path.length() == 1 && path.charAt(0) != '/')){
            return null;
        }
        Stack<String> process = new Stack<String>();
        boolean oneBlock = false;
        int index = 1;
        int startIndex = 0;
        while(index < path.length()){
            if(path.charAt(index) == '/' || index == path.length() - 1){
                oneBlock = true;
            }
            if(oneBlock){
                int base = 0;
                if(index == path.length() - 1 && path.charAt(index) != '/'){
                    base = 1;
                }
                String cur = path.substring(startIndex, index + base);
                startIndex = index;
                if(cur.equalsIgnoreCase("/..") && !process.isEmpty()){
                    process.pop();
                }
                if(!cur.equalsIgnoreCase("/..") && !cur.equalsIgnoreCase("/.") && !cur.equalsIgnoreCase("/")){
                    process.push(cur);
                }
                oneBlock = false;
            }
            index++;
        }
       
        if(process.isEmpty()){
            return "/";
        }
        StringBuilder result = new StringBuilder();
        while(!process.isEmpty()){
            result.insert(0, process.pop());
        }
       
        return result.toString();
    }
}