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Java Program to Iterate Over Characters in String

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  • Difficulty Level : Easy
  • Last Updated : 06 Jun, 2021
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Given string str of length N, the task is to traverse the string and print all the characters of the given string using java.

Illustration:

Input  : str = “GeeksforGeeks”
Output : G e e k s f o r G e e k s
Input  : str = "GfG"
Output : G f G

Methods:

  1. Using for loops(Naive approach)
  2. Using iterators (Optimal approach)

Method 1: Using for loops

The simplest or rather we can say naive approach to solve this problem is to iterate using a for loop by using the variable ‘i’ till the length of the string and then print the value of each character that is present in the string. 

Example

Java




// Java Program to Iterate Over Characters in String
  
// Class 1
// Main class
// To iterate over characters
class GFG {
  
    // Method 1
    // To traverse the string and
    // print the characters of the string
    static void getChar(String str)
    {
  
        // Traverse the string using for loop
        for (int i = 0; i < str.length(); i++) {
  
            // Printing the current character
            System.out.print(str.charAt(i));
  
            // Printing a space after each letter
            System.out.print(" ");
        }
    }
  
    // Method 2
    // Main driver method
    public static void main(String[] args)
    {
  
        // Creating a String variable to store the string
        String str = "GeeksforGeeks";
  
        // Calling the getChar method
        getChar(str);
    }
}


Output

G e e k s f o r G e e k s 

Time complexity is O(N) and space complexity is O(1)

Method 2: Using iterators

The string can be traversed using an iterator. We would be importing CharacterIterator and StringCharacterIterator classes from java.text package

Example:

Java




// Java Program to Iterate Over Characters in String
  
// Importing input output classes
import java.io.*;
// Importing CharacterIterator and StringCharacterIterator
// classes from java.text package
import java.text.CharacterIterator;
import java.text.StringCharacterIterator;
  
// Main class
// To iterate over characters
class GFG {
  
    // Method 1
    // To traverse the string and
    // print the characters of the string
    static void getChar(String str)
    {
  
        // Creating a CharacterIterator variable
        CharacterIterator itr
            = new StringCharacterIterator(str);
  
        // Iterating using while loop
        while (itr.current() != CharacterIterator.DONE) {
  
            // Print the current character
            System.out.print(itr.current());
  
            // Print a space after each letter
            System.out.print(" ");
  
            // Getting the next input from the user
            // using the next() method
            itr.next();
        }
    }
  
    // Method 2
    // Main driver method
    public static void main(String[] args)
    {
        // Creating a String variable to store the string
        String str = "GfG";
  
        // Calling the getChar method
        getChar(str);
    }
}


Output

G f G 

Time Complexity: O(N) and space complexity is of order O(1)


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