Question

我正在使用InputFilter类来制作支持数字分组的蒙版EditText。例如，当用户插入“12345”时，我想在EditText中显示“12,345”。我该如何实施呢？

这是我不完整的代码：

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

            for (int i = start; i < end; i++) {
                if (!Character.isLetterOrDigit(source.charAt(i))) {
                    return "";
                }
            }
            if (dest.length() > 0 && dest.length() % 3 == 0)
            {
                return "," + source;
            }
            return null;
        }
    };
    edtRadius.setFilters(new InputFilter[] { IF });

有没有其他方法可以实现这种输入掩码？

Answer 1

这是@vincent响应的改进。它添加了对1234 5678 9190格式中删除空格的检查，因此在尝试删除空格时，只需将光标后面的字符移动到空格前的数字即可。即使插入空格，它也会将光标保持在相同的相对位置。

    mTxtCardNumber.addTextChangedListener(new TextWatcher() {

        private boolean spaceDeleted;

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

        public void beforeTextChanged(CharSequence s, int start, int count, int after) {
            // check if a space was deleted
            CharSequence charDeleted = s.subSequence(start, start + count);
            spaceDeleted = " ".equals(charDeleted.toString());
        }

        public void afterTextChanged(Editable editable) {
            // disable text watcher
            mTxtCardNumber.removeTextChangedListener(this);

            // record cursor position as setting the text in the textview
            // places the cursor at the end
            int cursorPosition = mTxtCardNumber.getSelectionStart();
            String withSpaces = formatText(editable);
            mTxtCardNumber.setText(withSpaces);
            // set the cursor at the last position + the spaces added since the
            // space are always added before the cursor
            mTxtCardNumber.setSelection(cursorPosition + (withSpaces.length() - editable.length()));

            // if a space was deleted also deleted just move the cursor
            // before the space
            if (spaceDeleted) {
                mTxtCardNumber.setSelection(mTxtCardNumber.getSelectionStart() - 1);
                spaceDeleted = false;
            }

            // enable text watcher
            mTxtCardNumber.addTextChangedListener(this);
        }

        private String formatText(CharSequence text)
        {
            StringBuilder formatted = new StringBuilder();
            int count = 0;
            for (int i = 0; i < text.length(); ++i)
            {
                if (Character.isDigit(text.charAt(i)))
                {
                    if (count % 4 == 0 && count > 0)
                        formatted.append(" ");
                    formatted.append(text.charAt(i));
                    ++count;
                }
            }
            return formatted.toString();
        }
    });

Answer 2

如果你还在搜索，我在最后一天遇到了这个问题，并发现使用TextWatcher是最好的（仍然不是很好）选项。我不得不将信用卡号码的数字分组。

someEditText.addTextChagedListener(new TextWatcher()
{   
    //According to the developer guide, one shall only edit the EditText's
    //content in this function. 
    @Override
    public void afterTextChanged(Editable text)
    {
        //You somehow need to access the EditText to remove this listener
        //for the time of the changes made here. This is one way, but you
        //can create a proper TextWatcher class and pass the EditText to
        //its constructor, or have the EditText as a member of the class
        //this code is running in (in the last case, you simply have to
        //delete this line).
        EditText someEditText = (EditText) findViewById(R.id.someEditText);

        //Remove listener to prevent further call due to the changes we're
        //about to make (TextWatcher is recursive, this function will be
        //called again for every change you make, and in my experience,
        //replace generates multiple ones, so a flag is not enough.
        someEditText.removeTextChangedListener(this);

        //Replace text with processed the processed string.
        //FormatText is a function that takes a CharSequence (yes, you can
        //pass the Editable directly), processes it the way you want, then
        //returns the result as a String. 
        text.replace(0, text.length(), FormatText(text));

        //Place the listener back
        someEditText.addTextChangedListener(this);
    }

    @Override
    public void beforeTextChaged(CharSequence s, int start, int count, int after)
    {

    }

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

    }
});

我的信用卡号码格式化功能如下所示：

String FormatText(CharSequence text)
{
    StringBuilder formatted = new StringBuilder();

    int count = 0;
    for (int i = 0; i < text.length(); ++i)
    {
        if (Character.isDigit(text.charAt(i)))
        {
            //You have to be careful here, only add extra characters before a
            //user-typed character, otherwise the user won't be able to delete
            //with backspace, since you put the extra character back immediately.
            //However, this way, my solution would put a space at the start of
            //the string that I don't want, hence the > check.
            if (count % 4 == 0 && count > 0)
                formatted.append(' ');
            formatted.append(text.charAt(i));
            ++count;
        }
    }

    return formatted.toString();
}

您可能还需要考虑其他问题，因为每次进行更改时，此解决方案实际上都会重写EditText的内容。例如，您应该避免处理自己插入的字符（这是isDigit检查的另一个原因）。

Answer 3

使用简单的功能：

public String digit_grouping(String in_digit){

    String res = "";

    final int input_len = in_digit.length();
    for(int i=0 ; i< input_len ; i++)
    {

        if( (i % 3 == 0) && i > 0 )
            res = "," + res;

        res = in_digit.charAt(input_len - i - 1) + res;

    }

    return res;
}

如何使用InputFilter实现数字分组输入掩码？

3 个答案: