如何将字符串格式化为数字（123）456-7890

Question

I have a Caller.class which has a number stored as "1234567890," and I want the label lblCallbackNumber to be formatted as "(123) 456-789". This seems to be more complicated than I had though, and most web searches are showing people how to re-format a phone number as a regular number (the opposite of what I want)

Any help is greatly appreciated!

package SupportTool;

import javafx.scene.control.*;

import java.io.*;

public class mainCallController extends Main {

    public Label lblAccount;
    public Label lblCallbackNumber;
    public Label lblCallerName;
    public Label lblStoreNumber;

    public void initialize(){

        // LOAD CALLER INFORMATION
        Caller caller = new Caller();
        try{
            FileInputStream fis = new FileInputStream("caller.bin");
            ObjectInputStream ois = new ObjectInputStream(fis);
            caller = (Caller) ois.readObject();
            ois.close();
            fis.close();
        } catch (Exception e) {
            e.printStackTrace();
        }

        // SET LABELS TO CALLER DETAILS
        lblAccount.setText(caller.getAccount());
        String numberAsString = caller.getCallbackNumber();
        lblCallbackNumber.setText(phoneFormat(numberAsString));
        lblCallerName.setText(caller.getCallerName());
        lblStoreNumber.setText(caller.getStoreNumber());

    }

    private String phoneFormat (String number){
        if(number.length() == 10) {

            // TODO RETURN numberAsString FORMATTED AS "(123) 456-7890"

        } else {
            return number;
        }

    }

}

Answer 1

String s = "1234567890";

StringBuilder sb = new StringBuilder();
sb.append("(").append(s.substring(0,3)).append(") ").append(s.substring(3,6))
        .append("-").append(s.substring(6,9));
sb.toString();

Answer 2

You can use regexp for your task. Something like this

number = number.replaceFirst("(\\d{3})(\\d{3})(\\d{4})", "($1) $2-$3");

This code will split your phone number onto 3 blocks (3 digits, 3 digits, 4 digits) and place them in order of the pattern "($1) $2-$3"

The other way is to use StringBuilder to insert brackets and space

StringBuilder builder = new StringBuilder(number)
                            .insert(0,"(")
                            .insert(4,") ")
                            .insert(8,"-");

But in my opinin regexp is more usefull and clear.

Answer 3

I just answered my own question with the discovery of .substring. It appears this is a very basic answer. Thanks for the help, as I just started learning java only 2 weeks ago.