How to set jTextArea to have height that matches the size of a text it contains (to avoid scrollbars)

This problem looks trivial, but I can't find the solution.

When I create a form it contains a JTextArea. I want to put large constant text in it. If the text is say 1000 lines long, I want my JTextArea to be 1000 lines high (to be large enough to display the entire text without scrollbars). JTextArea is inside a p开发者_Go百科anel which can have scrollbar so it is not a problem when it gets too large (there are two JTextArea in that panel.. something like in a diff tool). Does anybody knows how can I achieve this? Thanks.

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The BorderLayout will handle the scrollbar out of the box if you simply put your JTextAreain a JScrollPane before you add it to your JPanel. FlowLayout, on the other hand, does not. It will not display the scroll bar unless, as @Xorty intimates, you call setPreferedSize() on your JScrollPane and give it the dimension that you would like.

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You can also use something like this (limited width, height depending on text, useful when showing info messages):

  public JTextArea createTextAreaFitToText(String message, Dimension minimalSize){

        JTextArea aMessagePanel = new JTextArea();
        aMessagePanel.setText(message);

        /*for modelToView to work, the text area has to be sized. It doesn't matter if it's visible or not.*/
        aMessagePanel.setPreferredSize(minimalSize);
        aMessagePanel.setSize(minimalSize);            

        Rectangle r = aMessagePanel.modelToView(aMessagePanel.getDocument().getLength()); 

        Dimension d = new Dimension(minimalSize.width, r.y + r.height);
        aMessagePanel.setPreferredSize(d);
        return aMessagePanel;

}

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To increase or decrease the height of JTextArea. When a text is entered, call for getPreferredSize() of JTextArea- it'll give you the size needed to display the whole text. After that use setPrefferedSize() of JScrollPane to set the size of JTextArea

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Well, first of all : it's JTextArea not jTextArea.

Now - put JTextArea into JScrollPane. When a text is entered, call for getPreferedSize() of JScrollPane - it'll give you precise size needed to display whole text. Also, I never use other LayoutManager than 'Free Design' from NetBeans Swing builder - so I am not sure how other LayoutManagers will behave there.