TextWatcher -替换字符串的最后一个字符

Question

每当“q”被写为我附加TextWatcher的edittext的最后一个字符时，这个“q”就会被替换为“a”。我使用:

public void afterTextChanged(Editable s) {
        // TODO Auto-generated method stub
        if(s.length() > 0 && s.toString().charAt(s.length()-1) == 'q')
        {
            current_string = s.toString();
            current_string = current_string.substring(0, (current_string.length()-1));
            et.setText(current_string);
            }
        }

但是，当我测试代码时，当我输入“q”时，什么也没发生。一些帮助？非常感谢。

Answer 1

不要使用< code>afterTextChanged,这是很危险的，因为它会被递归调用，你可能会陷入无限循环。

正如文档所说：

     It is legitimate to make further changes to s from this callback,
    but be careful not to get yourself into an infinite loop, because any 
   changes you make will cause this method to be called again recursively

改用onTextChanged。

在你的问题中

您忘记将字符a添加到字符串中

public void onTextChanged (CharSequence s, int start, int before, int count) {
    // TODO Auto-generated method stub
    if(s.length() > 0 && s.toString().charAt(s.length()-1) == 'q')
    {
        current_string = s.toString();
        current_string = current_string.substring(0, (current_string.length()-1));
        et.setText(current_string + "a"); //add the a after q is deleted
        }
    }
}