Live editing of users input

Question

Is it possible to auto insert characters into an EditText as the user inputs data?

I.e. if the user is entering a long number such as 123456789012, is it possible for this number to appear as he is typing it in the edit text box, but with a dash every 4th character?

So as you type the number above you would see it being entered in the EditText box but would look like this: 1234-5678-9012.

Currently I have an app where you can enter a long number and then press a button and it inserts the dashes for you, but I'm curious if it could be done as you type?

Many thanks for any help.

Answer 1

By tagging android, I think you are discussing about android editText, is so you can do it by listening the TextChangedListener,

EDITED: for backspace

editText.addTextChangedListener(new TextWatcher() {
            int len=0;
            @Override
            public void afterTextChanged(Editable s) { 
                String str = editText.getText().toString(); 
                 if(str.length()==4&& len <str.length()){//len check for backspace 
                    editText.append("-");
                }
            }

            @Override
            public void beforeTextChanged(CharSequence arg0, int arg1, int arg2, int arg3) {

             String str = editText.getText().toString(); 
              len = str.length();
            }

            @Override
            public void onTextChanged(CharSequence s, int start, int before, int count) {  
            }


        }); 

Answer 2

to solve this issue, i write a class "AutoAddTextWatcher" :

1. Auto insert text into EditText.
2. insert text into EditText at positions you are setted.
3. delete text in EditText at positions you are setted, when text length bigger than 1.

code snippet :

mEditText_birthday.addTextChangedListener(new AutoAddTextWatcher(mEditText_birthday,
            "/",
            new TextWatcher() {},
            4, 6));

AutoAddTextWatcher class

import android.text.Editable;
import android.text.TextWatcher;
import android.widget.EditText;


/**
 * Created by henry.chuang on 2016/5/12.
 */
public class AutoAddTextWatcher implements TextWatcher {
    private CharSequence mBeforeTextChanged;
    private TextWatcher mTextWatcher;
    private int[] mArray_pos;
    private EditText mEditText;
    private String mAppentText;

    public AutoAddTextWatcher(EditText editText, String appendText, int... position){
        this.mEditText = editText;
        this.mAppentText = appendText;
        this.mArray_pos = position.clone();
    }
    public AutoAddTextWatcher(EditText editText, String appendText, TextWatcher textWatcher, int... position){
        this(editText, appendText, position);
        this.mTextWatcher = textWatcher;
    }

    @Override
    public void beforeTextChanged(CharSequence s, int start, int count, int after) {
        mBeforeTextChanged = s.toString();

        if(mTextWatcher != null)
            mTextWatcher.beforeTextChanged(s, start, count, after);

    }

    @Override
    public void onTextChanged(CharSequence s, int start, int before, int count) {
        for (int i = 0; i < mArray_pos.length; i++) {
            if(((mBeforeTextChanged.length() - mAppentText.length() * i) == (mArray_pos[i] - 1) &&
                    (s.length() - mAppentText.length() * i) == mArray_pos[i])){
                mEditText.append(mAppentText);

                break;
            }

            if(((mBeforeTextChanged.length() - mAppentText.length() * i) == mArray_pos[i] &&
                    (s.length() - mAppentText.length() * i) == (mArray_pos[i] + 1))){
                int idx_start = mArray_pos[i] + mAppentText.length() * i;
                int idx_end = Math.min(idx_start + mAppentText.length(), s.length());

                String sub = mEditText.getText().toString().substring(idx_start,  idx_end);

                if(!sub.equals(mAppentText)){
                    mEditText.getText().insert(s.length() - 1, mAppentText);
                }

                break;
            }

            if(mAppentText.length() > 1 &&
                    (mBeforeTextChanged.length() - mAppentText.length() * i) == (mArray_pos[i] + mAppentText.length()) &&
                    (s.length() - mAppentText.length() * i) == (mArray_pos[i] + mAppentText.length() - 1)){
                int idx_start = mArray_pos[i] + mAppentText.length() * i;
                int idx_end = Math.min(idx_start + mAppentText.length(), s.length());

                mEditText.getText().delete(idx_start, idx_end);

                break;
            }

        }

        if(mTextWatcher != null)
            mTextWatcher.onTextChanged(s, start, before, count);

    }

    @Override
    public void afterTextChanged(Editable s) {
        if(mTextWatcher != null)
            mTextWatcher.afterTextChanged(s);

    }

}

complete demo source :
https://github.com/henrychuangtw/AutoInsertEditText