Question

im trying make one replace in string from a array but this dont work

dna[i].replace('T', 'C');

and with this way work?

"ATCTA".replace('T', 'C');

why dont work with array, how i can use use a replace in array[]

Now i have other problem, i want use various replaces in original string, how i can mahe this????

Answer 1

 String dna[] = {"ATCTA"};
 int i = 0;
 dna[i] = dna[i].replace('T', 'C');
 System.out.println(dna[i]);

This works as expected. Double check your code if you follow a similiar pattern.

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You may have expected, that dna[i].replace('T', 'C'); changes the content of the cell dna[i] directly. This is not the case, the String will not be changed, replace will return a new String where the char has been replaced. It’s necessary to assign the result of the replace operation to a variable.

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To answer your last comment:

Strings are immutable – you can’t change a single char inside a String object. All operations on Strings (substring, replace, ‘+’, …) always create new Strings.

A way to make more than one replace is like this:

dna[i] = dna[i].replace('T', 'C').replace('A', 'S');