How to print out specific letters within a String in Java

Question

I have been set a task to print out the 2nd, 3rd and 4th letter of a name within a String variable.

So for example the name is John and I want to print out the letters 'o, h and n only'

I was wondering if there is a specific method which I can use to carry out this task, if not what is the best approach to take?

Consider the .charAt() method of the String class, and use a loop initialized appropriately. The substring() method of String is also a possibility. Read the javadocs in the String class. — KevinO, Mar 29 '16 at 23:50
java has a lot of documentation [javadocs](https://docs.oracle.com/javase/8/docs/api/) You can usually find what you want with little effort. [substring](https://docs.oracle.com/javase/7/docs/api/java/lang/String.html#substring(int,%20int)) — BevynQ, Mar 29 '16 at 23:56

score 2 · Answer 1 · answered Mar 29 '16 at 23:58

2

Assuming the name always has at least 4 letters in it, this code will work:

public static void main(String[] args) {
    String name = "JOHN";
    System.out.println(name.substring(1,4));
}

answered Mar 29 '16 at 23:58

Aaron

992
3
15
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robotlos · Accepted Answer · 2016-03-30T00:17:03.270

EDIT as @KevinO pointed out, determining whether the name length or 4 is smaller solves issues that would cause exceptions. I updated to incorporate this input.

Depends on how you're trying to print it. You can use a for loop and iterate starting at the 1st index of your String name like so:

String name = "John";
for(int i = 1; i < Math.min(name.length(), 4); i++){
    System.out.print(name.charAt(i));
}

Sample Run:

run:
ohn
BUILD SUCCESSFUL (total time: 0 seconds)

You could print out theCharacter one at a time like:

System.out.print(name.charAt(1)); //print character at index 1
System.out.print(name.charAt(2)); //print character at index 2
System.out.print(name.charAt(3)); //print character at index 3

This might be unsafe because you're not sure if the name will in be in fact at least 4 Characters long. Sample run:

run:
ohn
BUILD SUCCESSFUL (total time: 0 seconds)

Or perhaps the easiest way which is also safe, you could print it out using String.substring() which takes in a range, like so:

    System.out.println(name.substring(1, Math.min(name.length(), 4)));

This results in:

run:
ohn
BUILD SUCCESSFUL (total time: 0 seconds)

.substring(1, Min(name.length(), 4)) avoids the last problem of String length. The first solution doesn't stop at the 3rd printed character (it has name.length() but the question was character 2,3,4 only) if I read the question correctly. — KevinO, Mar 30 '16 at 00:13
@KevinO, right, incorporated your input into my answer. Thanks! — robotlos, Mar 30 '16 at 00:18

Sajeev · Answer 3 · 2016-04-19T04:54:03.557

0

You can do that by using charAt function on String . The following version of code should do what you are asking for.

public static void main(String[] args) {
    String input = "John";
    if (input != null && input.length() > 1) { 
               System.out.println(input.substring(1, Math.min(input.length(), 4)));     
    }
}

edited Apr 19 '16 at 04:54

answered Mar 29 '16 at 23:53

Sajeev

818
7
23

This can work, but it is verbose and hard to maintain. Furthermore, it will print in a stacked column rather than on the same line. (Meed to use print not println). – KevinO Mar 30 '16 at 00:01
@KevinO code edited to meet your concerns. We have to check length to avoid StringIndexOutOfBoundsException – Sajeev Mar 30 '16 at 00:08
1

yes, the StringIndexOutOfBounds is a concern. But consider `if (input != null && input.length() > 1) { System.out.println(input.substring(1, Math.min(input.length(), 4))); }`. One only needs to ensure the length is greater than one. – KevinO Mar 30 '16 at 00:10
@KevinO good one. I liked you solution. – Sajeev Mar 30 '16 at 00:11
@KevinO I have applied your suggestion to the answer thanks. – Sajeev Apr 19 '16 at 04:54

How to print out specific letters within a String in Java

3 Answers3