QT textedit如何限定输入字数

QT textedit如何限定输入字数

方法一：
mEditText.setFilters(new InputFilter[]{new InputFilter.LengthFilter(Constants.MAX_TEXT_INPUT_LENGTH)});

方法二：
private TextWatcher mTextWatcher = new TextWatcher(){
Toast mToast = null;
public void beforeTextChanged(CharSequence s, int start,
int count,int after) {
}
public void onTextChanged(CharSequence s, int start,
int before,int count) {
}

public void afterTextChanged(Editable s) {
int nSelStart = 0;
int nSelEnd = 0;
boolean nOverMaxLength = false;

nSelStart = mEditText.getSelectionStart();
nSelEnd = mEditText.getSelectionEnd();

nOverMaxLength = (s.length() > Constants.MAX_TEXT_INPUT_LENGTH) ? true : false;
if(nOverMaxLength){
if(null == mToast){
mToast = Toast.makeText(mContext,
R.string.IDS_MSG_TEXT_OVER_MAXLENGTH,
Toast.LENGTH_SHORT);
}
mToast.show();

s.delete(nSelStart - 1, nSelEnd);
mEditText.setTextKeepState(s);//请读者注意这一行，保持光标原先的位置，而 mEditText.setText(s)会让光标跑到最前面，
//就算是再加mEditText.setSelection(nSelStart) 也不起作用
}
}
};

连接document ()的contentschange信号: void qtextdocument::contentschange ( int position, int charsremoved, int charsadded ) [signal] this signal is emitted whenever the document's content changes; for example, when text is inserted or deleted, or when formatting is applied. information is provided about the position of the character in the document where the change occurred, the number of characters removed (charsremoved), and the number of characters added (charsadded). the signal is emitted before the document's layout manager is notified about the change. this hook allows you to implement syntax highlighting for the document. see also qabstracttextdocumentlayout::documentchanged() and contentschanged().