how to change the character of a string in java

To change a specific character of a string in Java, you can use the charAt method of the String class to get the character at a specific index, and then use the substring method to create a new string with the modified character.

Here's an example of how you might do this:

String str = "Hello, World!";
char ch = 'a';  // The new character
int index = 1;  // The index of the character to be replaced

String newStr = str.substring(0, index) + ch + str.substring(index + 1);

System.out.println(newStr);  // Output: Hallo, World!

In this example, the substring method is used to create a new string by concatenating three substrings: the substring before the character to be replaced, the new character, and the substring after the character to be replaced.