EditText showing numbers with 2 decimals at all times

Question

I would like to display the input of the EditText fields with two decimals at all times. So when the user enters 5 it will show 5.00 or when the user enters 7.5 it will show 7.50.

Besides that I would like to also show zero when the field is empty instead of nothing.

What I've got already is the inputtype set to:

android:inputType="number|numberDecimal"/>

Should I work with inputfilters here?

Sorry I still quite new to android / java...

Thanks for your help!

Edit 2011-07-09 23.35 - Solved part 1 of 2: The "" to 0.00.

With the answer of nickfox I was able to solve half of my question.

    et.addTextChangedListener(new TextWatcher() {
        public void afterTextChanged(Editable s) {}
        public void beforeTextChanged(CharSequence s, int start, int count, int after) {}
        public void onTextChanged(CharSequence s, int start, int before, int count) {
            if(s.toString().matches(""))
            {
                et.setText("0.00");
                Selection.setSelection(et.getText(), 0, 4);
            } 
        }
    });

I'm still working on a solution for the other half of my question. If I found the solution I will post it here too.

Edit 2011-07-09 23.35 - Solved part 2 of 2: Change user input to a number with two decimals.

OnFocusChangeListener FocusChanged = new OnFocusChangeListener() {

    @Override
    public void onFocusChange(View v, boolean hasFocus) {
        if(!hasFocus){
            String userInput = et.getText().toString();

            int dotPos = -1;    

            for (int i = 0; i < userInput.length(); i++) {
                char c = userInput.charAt(i);
                if (c == '.') {
                    dotPos = i;
                }
            }

            if (dotPos == -1){
                et.setText(userInput + ".00");
            } else {
                if ( userInput.length() - dotPos == 1 ) {
                    et.setText(userInput + "00");
                } else if ( userInput.length() - dotPos == 2 ) {
                    et.setText(userInput + "0");
                }
            }
        }
    }

Answer 1

Update #2

Correct me if I'm wrong, but oficial docs to TextWatcher say that it's legitimate use afterTextChanged method for make changes to... EditText content for this task.

I have the same task in my multy-language app and as I know it's possible , or . symbols as separator so I modify nickfox answer for 0.00 format with total limit of symbols to 10:

Layout (Updated):

<com.custom.EditTextAlwaysLast
        android:id="@+id/et"
        android:layout_height="wrap_content"
        android:layout_width="fill_parent"
        android:maxLength="10"
        android:layout_marginTop="50dp"
        android:inputType="numberDecimal"
        android:gravity="right"/>

EditTextAlwaysLast class:

import android.content.Context;
import android.graphics.Canvas;
import android.util.AttributeSet;
import android.widget.EditText;

/**
 * Created by Drew on 16-01-2015.
 */
public class EditTextAlwaysLast extends EditText {

    public EditTextAlwaysLast(Context context) {
        super(context);
    }

    public EditTextAlwaysLast(Context context, AttributeSet attrs) {
        super(context, attrs);
    }

    public EditTextAlwaysLast(Context context, AttributeSet attrs, int defStyleAttr) {
        super(context, attrs, defStyleAttr);
    }

    @Override
    protected void onSelectionChanged(int selStart, int selEnd) {
    //if just tap - cursor to the end of row, if long press - selection menu
        if (selStart==selEnd)
            setSelection(getText().length());
       super.onSelectionChanged(selStart, selEnd);
}


}

Code in ocCreate method (Update #2):

EditTextAlwaysLast amountEditText;
    Pattern regex;
    Pattern regexPaste;

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


        amountEditText = (EditTextAlwaysLast)findViewById(R.id.et);


        DecimalFormatSymbols dfs = new DecimalFormatSymbols(getResources().getConfiguration().locale);
        final char separator =  dfs.getDecimalSeparator();

        //pattern for simple input
        regex = Pattern.compile("^(\\d{1,7}["+ separator+"]\\d{2}){1}$");
        //pattern for inserted text, like 005 in buffer inserted to 0,05 at position of first zero => 5,05 as a result
        regexPaste = Pattern.compile("^([0]+\\d{1,6}["+separator+"]\\d{2})$");

        if (amountEditText.getText().toString().equals(""))
            amountEditText.setText("0"+ separator + "00");

        amountEditText.addTextChangedListener(new TextWatcher() {

            public void afterTextChanged(Editable s) {
                if (!s.toString().matches(regex.toString())||s.toString().matches(regexPaste.toString())){

                    //Unformatted string without any not-decimal symbols
                    String coins = s.toString().replaceAll("[^\\d]","");
                    StringBuilder builder = new StringBuilder(coins);

                    //Example: 0006
                    while (builder.length()>3 && builder.charAt(0)=='0')
                        //Result: 006
                        builder.deleteCharAt(0);
                    //Example: 06
                    while (builder.length()<3)
                        //Result: 006
                        builder.insert(0,'0');
                    //Final result: 0,06 or 0.06
                    builder.insert(builder.length()-2,separator);
                    amountEditText.setText(builder.toString());
                }
                amountEditText.setSelection(amountEditText.getText().length());
            }
            public void beforeTextChanged(CharSequence s, int start, int count, int after) {}

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

        });
    }

It's look like the best result for me. Now this code support copy-paste actions