Android 自定义输入手机号自动添加分隔符

public class AccountTxtView extends android.support.v7.widget.AppCompatEditText {
  private final char CUT = '-';
  public AccountTxtView(Context context) {
    super(context);
  }
  public AccountTxtView(Context context, AttributeSet attrs) {
    super(context, attrs);
  }
  public AccountTxtView(Context context, AttributeSet attrs, int defStyleAttr) {
    super(context, attrs, defStyleAttr);
  }
  @Override
  protected void onTextChanged(CharSequence text, int start, int lengthBefore, int lengthAfter) {
    if (text == null || text.length() == 0)
      return;
    StringBuilder sb = new StringBuilder();
    for (int i = 0; i < text.length(); i++) {//添加分割符
      if (i != 3 && i != 8 && text.charAt(i) == CUT) {
        continue;
      } else {
        sb.append(text.charAt(i));
        if ((sb.length() == 4 || sb.length() == 9)
            && sb.charAt(sb.length() - 1) != CUT) {
          sb.insert(sb.length() - 1, CUT);
        }
      }
    }
    //防止多次设置值
    if (!sb.toString().equals(text.toString())) {
      int index = start + 1;
      if (sb.charAt(start) == CUT) {
        if (lengthBefore == 0) {
          index++;
        } else {
          index--;
        }
      } else {
        if (lengthBefore == 1) {
          index--;
        }
      }
      setText(sb.toString());
      setSelection(index);
    }else{//删除时候判断
      String line = text.subSequence(text.length() - 1, text.length()).toString();
      if (line.equals(String.valueOf(CUT))) {//如果删除碰到‘-'符号，则默认去除
        sb.deleteCharAt(text.subSequence(0, text.length() - 1).length());
        setText(sb.toString());
        setSelection(sb.length());
      }
    }
  }
  public String getPhone() {
    String result = null;
    String val = getText().toString();
    if (val == null || val.isEmpty())
      return "";
    result = val.replace(String.valueOf(CUT), "");
    return result;
  }
}