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Java - replace first character in string
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In this article, we would like to show you how to replace the first character in string in Java.
Quick solution:
xxxxxxxxxx1
String text = "ABC";2
String replacement = "x";3
String result = replacement + text.substring(1);4
5
System.out.println(result); // xBCor:
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String text = "ABC";2
String replacement = "x";3
String result = replacement.concat(text.substring(1));4
5
System.out.println(result); // xBCor:
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String text = "ABC";2
String replacement = "x";3
String result = text.replaceAll("^.", replacement);4
5
System.out.println(result); // xBC
In this example, we remove last character from the original string and add the replacement at the beginning.
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public class Example {2
3
public static void main(String[] args) {4
String text = "ABC";5
String replacement = "x";6
String result = replacement + text.substring(1);7
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System.out.println(result); // xBC9
}10
}This approach is equivalent to the above one. Instead of + operator we concatenate the strings using concat() method.
xxxxxxxxxx1
public class Example {2
3
public static void main(String[] args) {4
String text = "ABC";5
String replacement = "x";6
String result = replacement.concat(text.substring(1));7
8
System.out.println(result); // xBC9
}10
}In this example, we use string replaceAll() with "^." regex to replace the first character in the text string.
Regex explanation:
^- matches the beginning of the string,.- matches any character except linebreaks.
xxxxxxxxxx1
public class Example {2
3
public static void main(String[] args) {4
String text = "ABC";5
String replacement = "x";6
String result = text.replaceAll("^.", replacement);7
8
System.out.println(result); // xBC9
}10
}Note:
Regular expressions are slower than
substring()method.
