java - JTextArea not editable -

i came across following problem. want have scrollable jtextarea , create 1 that:

jscrollpane scrollabletextarea = new jscrollpane(); jtextarea text = new jtextarea(); scrollabletextarea.add(text); 

the result have grey field cannot write into.

if create jtextarea works:

jscrollpane scrollabletextarea = new jscrollpane(new jtextarea()); 

where mistake leads behaviour?

if create jtextarea works:

a jscrollpane uses own custom layout manager. scrollpane contains areas for:

1. horizontal/vertical scrollbars
2. a "row header" , "column header"
3. components @ top/right , top/left of scroll pane
4. the "viewport" used contain component want scroll

when use following:

scrollabletextarea.add(text); 

this mess scroll pane because component added scroll pane directly , not viewport of scroll pane

when use:

jscrollpane scrollabletextarea = new jscrollpane(new jtextarea(5, 20)); 

this create scroll pane , add text area viewport of scroll pane.

read section swing tutorial on how use scrollpanes more information on how scroll pane works.