Question 8 : Find length of String without using any inbuilt method in java?

 Solution: You can use try-catch block for catching StringIndexOutOfBoundException and when this exception is thrown, you can simply return I (Index at which you will get the exception)

Using toCharArray is the simplest solution.

Using toCharArray

Logic

• Convert string to char array using toCharArray method
• Iterate over char array and incrementing length variable.

Program:

public class LenghtOfStringMain{
 
 public static void main(String args[]){
 
  String helloWorld="This is hello world";
  System.out.println("length of helloWorld string :"+getLengthOfStringWithCharArray(helloWorld));
  }
 
  public static int getLengthOfStringWithCharArray(String str)
  {
       int length=0;
       char[] strCharArray=str.toCharArray();
       for(char c:strCharArray) {
               length++;
          }
    return length;
  }
}

When you run the above program, you will get the following output::

length of helloWorld string :19

Using StringIndexOutOfBoundsException

You must be wondering how we can use StringIndexOutOfBoundsException to find length of String without using length() method. Please refer below logic :

Logic

• Initialize i with 0 and iterate over String without specifying any condition. So it will be always true.
• Once value of i will be more than length of String, it will throw StringIndexOutOfBoundsException exception.
• We will catch the exception and return i after coming out of catch block.

Program:

publicclass LenghtOfStringMain{
 
 public static void main(String args[]){
 
  String helloWorld="This is hello world";
  System.out.println("length of helloWorld string :"+getLengthOfString(helloWorld));
 
  }
 
  public static int getLengthOfString(String str)
  {
    int i=0;
  try{
   for(i=0;;i++)
   {
    str.charAt(i);
   }
 
  }
  catch(Exception e)
  {
 
  }
  return i;
 }
}

When you run the above program, you will get the following output::
length of helloWorld string :19

That’s all about How to find the length of the string in java without using length() method.

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