Java String Formatting based on Pattern

This is what i can do for you

public class HelloWorld{

 public static void main(String []args){
   String input = "1234567890";
   String patter = "(%s) %s-%s";
   HelloWorld hello = new HelloWorld();
   hello.formatNumber(input,patter);
 }
 public String formatNumber(String input, String patter) {
    System.out.println(input);
    System.out.println(patter);
    System.out.println(String.format(patter,input.substring(0,3),input.substring(3,6),input.substring(6,10)));
    return null;
 }
}

You can modify it according to your needs

Ok, how about this solution:

Giving credit to @Code Jockey in this post, you could use this regex to match and format valid phone numbers.

There are many variations to this regex and it is very thorough yet flexible. See the example link. Very clever.

Regex:

^\D*1?\D*([2-9])\D*(\d)\D*(\d)\D*(\d)\D*(\d)\D*(\d)\D*(\d)\D*(\d)\D*(\d)\D*(\d).*$

Replace:

($1$2$3) $4$5$6-$7$8$9$10

Example:

http://regex101.com/r/wM0nU5

Then if match is false, (not a valid phone number), as in your example:

123456
1234567
1234567890
12

You would use another regex, to match and format the invalids - such as:

(.{1,3})(.{1,3})(.{1,3})

Replace:

($1) $2-$3

Example:

http://regex101.com/r/wY3kP2

Personal note: I don't know why you would want to match and format a non-valid phone number. personally I would use the first regex to format valid numbers and then on false matches, request the user to input a valid number. However, I do understand that, with not knowing the exact situation or application, there may be the need or exception somehow to format an invalid phone number.

You don't need to apply regex,you can just filter out the input.

I have created a sample app , I hope it will be helpful !!

MainActivity.java

package com.mehuljoisar.d_asyoutypeformatter;

import android.os.Bundle;
import android.app.Activity;
import android.text.InputFilter;
import android.text.Spanned;
import android.util.Log;
import android.view.Menu;
import android.widget.EditText;

public class MainActivity extends Activity {

    private EditText etCellNumber;

    private InputFilter mCellNumFilter = new InputFilter() {

        @Override
        public CharSequence filter(CharSequence source, int start, int end, Spanned dest, int dstart, int dend) {

            Log.d("dstart", ""+dstart);
            if (source.length() > 0) {

                if (!Character.isDigit(source.charAt(0)))
                    return "";
                else {
                    if (dstart == 0) {
                        return "(" + source;
                    }
                    else if (dstart == 3) {
                        return source + ") ";
                    } 
                    else if (dstart == 9)
                        return "-" + source;
                    else if (dstart >= 14)
                        return "";
                }

            } else {

            }

            return null;

        }
    };

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        etCellNumber = (EditText)findViewById(R.id.etCellNumber);
        etCellNumber.setFilters(new InputFilter[] { mCellNumFilter });
    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        // Inflate the menu; this adds items to the action bar if it is present.
        getMenuInflater().inflate(R.menu.main, menu);
        return true;
    }

}

activity_main.xml

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent">


<EditText
    android:id="@+id/etCellNumber"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:inputType="phone"
    android:hint="enter cell number" />

Screenshots :