EditText输入手机号自动带空格

xml:

<EditText
    android:id="@+id/edit_main"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:hint="请输入手机号"
    android:inputType="number"
    android:maxLength="13"/>

Activity:

mEditText = (EditText) findViewById(R.id.edit_main);
mEditText.addTextChangedListener(new TextWatcher() {
    @Override
    public void beforeTextChanged(CharSequence s, int start, int count, int after) {

    }

    @Override
    public void onTextChanged(CharSequence charSequence, int start, int before, int count) {
        if (charSequence == null || charSequence.length() == 0)
            return;
        StringBuilder stringBuilder = new StringBuilder();
        for (int i = 0; i < charSequence.length(); i++) {
            if (i != 3 && i != 8 && charSequence.charAt(i) == ' ') {
                continue;
            } else {
                stringBuilder.append(charSequence.charAt(i));
                if ((stringBuilder.length() == 4 || stringBuilder.length() == 9)
                        && stringBuilder.charAt(stringBuilder.length() - 1) != ' ') {
                    stringBuilder.insert(stringBuilder.length() - 1, ' ');
                }
            }
        }
        if (!stringBuilder.toString().equals(charSequence.toString())) {
            int index = start + 1;
            if (stringBuilder.charAt(start) == ' ') {
                if (before == 0) {
                    index++;
                } else {
                    index--;
                }
            } else {
                if (before == 1) {
                    index--;
                }
            }
            mEditText.setText(stringBuilder.toString());
            mEditText.setSelection(index);
        }
    }

    @Override
    public void afterTextChanged(Editable s) {

    }
});