Replacing last 4 characters with a "*"

Question

I have a string and I need to replace the last 4 characters of the string with a "*" symbol. Can anyone please tell me how to do it.

Solution 1

A quick and easy method...

public static String replaceLastFour(String s) {
    int length = s.length();
    //Check whether or not the string contains at least four characters; if not, this method is useless
    if (length < 4) return "Error: The provided string is not greater than four characters long.";
    return s.substring(0, length - 4) + "****";
}

Now all you have to do is call replaceLastFour(String s) with a string as the argument, like so:

public class Test {
    public static void main(String[] args) {
        replaceLastFour("hi");
        //"Error: The provided string is not greater than four characters long."
        replaceLastFour("Welcome to StackOverflow!");
        //"Welcome to StackOverf****"
    }

    public static String replaceLastFour(String s) {
        int length = s.length();
        if (length < 4) return "Error: The provided string is not greater than four characters long.";
        return s.substring(0, length - 4) + "****";
    }
}

Solution 2

The simplest is to use a regular expression:

String s = "abcdefg"
s = s.replaceFirst(".{4}$", "****"); => "abc****"

Solution 3

Maybe an example would help:

String hello = "Hello, World!";
hello = hello.substring(0, hello.length() - 4);
// hello == "Hello, Wo"
hello = hello + "****";
// hello == "Hello, Wo****"

Solution 4

public class Model {
    public static void main(String[] args) {
        String s="Hello world"; 
        System.out.println(s.substring(0, s.length()-4)+"****");
    }
}

Solution 5

You can use substring for this.

String str = "mystring";
str = str.substring(0,str.length()-4);
str = str + "****";

So substring takes two parameter.

substring(beginIndex, endIndex);

So, if you call a substring method in a string, It creates a new String that begins from beginIndex inclusive and endIndex exclusive. For example:

String str = "roller";
str = str.substring(0,4);
System.out.Println("str");

OUTPUT :

roll

so it starts from the beginIndex until the endIndex - 1.

If you want to know more about substring, visit http://docs.oracle.com/javase/1.4.2/docs/api/java/lang/String.html

Hope this helps.

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Comments

[Opeyemi Sanusi]

not exactly what i was looking for but it helped me figure out what i was looking for