Java 17 Recipes

3-12. Iterating Over the Characters of a String
 Problem
You want to iterate the characters in a string of text so that you can manipulate them at 
the character level.
 Solution
Use a combination of string helper methods to access the string at a character level. If 
you use a string helper method within the context of a loop, you can easily traverse a 
string by character. In the following example, the string named str is broken down using 
the toCharArray() method.
String str = "Break down into chars";
System.out.println(str);
for (char chr : str.toCharArray()){
System.out.println(chr);
}
Chapter 3 StringS

---

96
The same strategy could be used with the traditional for loop. An index could be 
created to allow access to each character of the string using the charAt() method.
for (int x = 0; x <= str.length()-1; x++){
System.out.println(str.charAt(x));
}
Both solutions yield the following result.
B
r
e
a
k
d
o
w
n
i
n
t
o
c
h
a
r
s
Note the first example using toCharArray() generates a new character 
array. therefore, the second example, using the traditional for loop, might 
perform faster.
Chapter 3 StringS

---

97
 How It Works
String objects contain methods that can be used for performing various tasks. The 
solution to this recipe demonstrates a number of different String methods. The 
toCharArray() method can be called against a string in order to break it into characters 
and then store those characters in an array. This method is very powerful, and it 
can save a bit of time when performing this task is required. The result of calling the 
toCharArray() method is a char[], which can then be traversed using an index. Such 
is the case in the solution to this recipe. An enhanced for loop iterates through the 
contents of the char[] and print out each of its elements.
The length() method finds the number of characters contained within a string. The 
result is an int value that can be very useful in the context of a for loop, as demonstrated 
in the solution to this recipe. In the second example, the length() method finds the 
number of characters in the string so that they can be iterated using the charAt() 
method. The charAt() method accepts an int index value as an argument and returns 
the character that resides at the given index in the string.
Often the combination of two or more String methods can obtain various results. 
In this case, using the length() and charAt() methods within the same code block 
provided the ability to break down a string into characters.