EditText et_content;//定義一個文本輸入框TextView tv_num;// 用來顯示剩余字數int num = 10;//限制的最大字數

et_content = (EditText) findViewById(R.id.et_content);tv_num = (TextView) findViewById(R.id.tv_num);tv_num.setText("10");

et_content.addTextChangedListener(new TextWatcher() {  private CharSequence temp;  private int selectionStart;  private int selectionEnd;  @Override  public void onTextChanged(CharSequence s, int start, int before,      int count) {    temp = s;    System.out.println("s="+s);  }  @Override  public void beforeTextChanged(CharSequence s, int start, int count,      int after) {  }  @Override  public void afterTextChanged(Editable s) {    int number = num - s.length();    tv_num.setText("" + number);    selectionStart = et_content.getSelectionStart();    selectionEnd = et_content.getSelectionEnd();    //System.out.println("start="+selectionStart+",end="+selectionEnd);    if (temp.length() > num) {      s.delete(selectionStart - 1, selectionEnd);      int tempSelection = selectionStart;      et_content.setText(s);      et_content.setSelection(tempSelection);//設置光標在最后    }  }});