java - 获取更改的行 jtextarea

Question

我正在做一个需要自定义验证的文本编辑器。由于内容非常大，我想到只验证更改或添加的行。验证错误通过行号显示，例如“Line: 10不能超过15个字符”

1. 对于单行，每次用户更改时都会验证当前行，并保留行号作为引用。 - 已解决

2. 用户可以复制文本并粘贴多行。为此，想到了 getSelectionStart 和 getSelectionEnd。有没有办法从 getSelectionStart 和 getSelectionEnd 获取行号，以便我可以获得起始行和结束行？

经过一些实验，我认为选择可见的行将解决我上面提到的第二个问题。

矩形将解决获取可视区域的x，y坐标并编写代码，我想我快完成了。但是，我没有正确获得结束行号，

      [code]
    //editor is jtextarea
      Rectangle r = editor.getVisibleRect();
      Point top = new Point(r.x, r.y);
      Point bottom = new Point(r.x, r.y + r.height);
      int startRow = editor.viewToModel(top); /* this is working. it shows 0 at           initial, then after the line reaches the end and when the scrollbar gets displayed, it shows the numbers correctly, 1,2,3...*/
     int endRow = editor.viewToModel(bottom); /* this is not working, when we type, it is taking column numbers */
     editorLineNo.setText(" START ROW " + startRow + " END ROW" + endRow);
     [/code]

     What is needed is, start row number and end row number from the viewable area  of jtextarea  

Answer 1

Is there a way of getting the row numbers ...

Element root = textArea.getDocument().getDefaultRootElement();
int row = root.getElementIndex( selectionStart ) + 1;