Java Program to Iterate Over Characters in String

06 Jun, 2021
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:
Using for loops(Naive approach)Using iterators (Optimal approach)
Using for loops(Naive approach)
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 charactersclass 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);    }}
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 classesimport java.io.*;// Importing CharacterIterator and StringCharacterIterator// classes from java.text packageimport java.text.CharacterIterator;import java.text.StringCharacterIterator;  // Main class// To iterate over charactersclass 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);    }}
G f G 
Time Complexity: O(N) and space complexity is of order O(1)
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