how to push back a character in string in java

Question

String str1 = "hello world";
String str2;
for (int i=0; i<str1.length(); i++)
{
    str2 = str2 + str1[i];
}

how do I push back elements of str1 in str2 sequencially?

It's really unclear what you want str2 to be after this loop has completed. — Jon Skeet, Apr 29 '13 at 14:26
Please consider using a `StringBuilder` for repeated concatenation due to the immutability of `String` objects, but also consider revising your solution to your problem; I'm unsure of the context of what you're trying to do but perhaps some sort of `Stack` implementation would suit your scenario better? — Quetzalcoatl, Apr 29 '13 at 14:30
possible duplicate of [Why StringBuilder when there is String?](http://stackoverflow.com/questions/5234147/why-stringbuilder-when-there-is-string) — Sam Harwell, Apr 29 '13 at 14:30
Why would you not just use `str1 + str2`, which has the same effect as the whole for loop? — Louis Wasserman, Apr 29 '13 at 16:36

score 4 · Accepted Answer · answered Apr 29 '13 at 14:26

4

Don't forget to initialize String str2 = ""; . After that, do this inside the loop:

str2 = str2 + str1.charAt(i);

Or equivalently:

str2 += str1.charAt(i);

Either way, the trick is using the charAt() method for accessing a character at a given position.

answered Apr 29 '13 at 14:26

Óscar López

And what if I want to check a character that whether it is alphabet or not? – Fatima Batool Apr 29 '13 at 14:32
That's a separate question, but OK. Use the methods in the `Character` class, in particular `Character.isAlphabetic()`. – Óscar López Apr 29 '13 at 14:37

Sushim Mukul Dutta · Answer 2 · 2013-04-29T14:50:56.313

3

Instead of str1[i] use str1.charAt(i).

for (int i=0; i<str1.length(); i++)
{
str2 = str2 + str1.charAt(i);
}

edited Apr 29 '13 at 14:50

answered Apr 29 '13 at 14:27

score 2 · Answer 3 · answered Apr 29 '13 at 14:26

Strings are immutable.... cannot be changed after adding them.... you cannot change them, but you can create new ones with the result you want.

Typically, you should use StringBuilder to do the manipulation, and the toString() at the end to get a final String result.

score 0 · Answer 4 · answered Apr 29 '13 at 14:29

String str1 = "hello world";
String str2 = "";
for (int i=0; i<str1.length(); i++)
{
    str2 = str2 + str1.charAt(i);
}

If you need to push the contents as a Stack, i.e. reverse the String.

String str1 = "hello world";
String str2 = "";
for (int i=str1.length()-1; i>-1; i--)
{
    str2 = str2 + str1.charAt(i);
}
System.out.println(str2);

score 0 · Answer 5 · edited May 23 '17 at 12:24

0

You should look at the answers to the following questions.

edited May 23 '17 at 12:24

Community

answered Apr 29 '13 at 14:30

Sam Harwell

5 Answers5