Remove Parentheses Content

Program to accept a sentence and remove all parentheses contents. In case the parentheses are only opened or only closed then show appropriate error message.

Example 1: “The Sun rises (at noon(4pm)) from East”. The program should remove all parentheses contents including the parentheses giving us an output “The Sun rises from East”.

Example 2: “The Sun rises (at noon (4pm) from East”. Since all the parentheses are not closed the program should output an error message.

Java

import java.util.*;
public class RemParentheses
{
    public static void main(String args[])
    {
        String str="",nstr="";
        int l=0,count=0;
        char ch=' ';
        Scanner sc=new Scanner(System.in);
        System.out.print("Enter a string: ");
        str=sc.nextLine();
        str=str.trim();
        l=str.length();
        for(int i=0;i<l;i++)
        {
            ch=str.charAt(i);
            if(ch=='(')
            {
                nstr=nstr.trim();
                count++;
            }
            else if(ch==')')
            {
                count--;
            }
            else if(count==0)
            {
                nstr=nstr+ch;
            }
        }
        if(count==0)
        {
            System.out.println("New string: "+nstr);
        }
        else
        {
            System.out.println("Error!! Invalid string");
        }
    }
}

Java