Java Difference between the setPreferredSize and setSize methods in components

Question

What is the main difference between setSize   and setPreferredSize    Sometimes I used setSize    sometimes setPreferredSize    sometimes one does what I want  sometimes the other  What call should I use for JFrames and JPanels

User · Answer

IIRC      setSize sets the size of the component   setPreferredSize sets the preferred size   The Layoutmanager will try to arrange that much space for your component   It depends on whether you re using a layout manager or not

User · Answer

Usage depends on whether the component s parent has a layout manager or not   setSize   -- use when a parent layout manager does not exist  setPreferredSize    also its related setMinimumSize and setMaximumSize  -- use when a parent layout manager exists   The setSize   method probably won t do anything if the component s parent is using a layout manager  the places this will typically have an effect would be on top-level components  JFrames and JWindows  and things that are inside of scrolled panes   You also must call setSize   if you ve got components inside a parent without a layout manager  Generally  setPreferredSize   will lay out the components as expected if a layout manager is present  most layout managers work by getting the preferred  as well as minimum and maximum  sizes of their components  then using setSize   and setLocation   to position those components according to the layout s rules  For example  a BorderLayout tries to make the bounds of its  quot north quot  region equal to the preferred size of its north component---they may end up larger or smaller than that  depending on the size of the JFrame  the size of the other components in the layout  and so on

User · Answer

setSize will resize the component to the specified size   setPreferredSize sets the preferred size   The component may not actually be this size depending on the size of the container it s in  or if the user re-sized the component manually

User · Answer

setSize   or setBounds   can be used when no layout manager is being used   However  if you are using a layout manager you can provide hints to the layout manager using the setXXXSize   methods like setPreferredSize   and setMinimumSize   etc    And be sure that the component s container uses a layout manager that respects the requested size  The FlowLayout  GridBagLayout  and SpringLayout managers use the component s preferred size  the latter two depending on the constraints you set   but BorderLayout and GridLayout usually don t If you specify new size hints for a component that s already visible  you need to invoke the revalidate method on it to make sure that its containment hierarchy is laid out again  Then invoke the repaint method

[java] Java: Difference between the setPreferredSize() and setSize() methods in components

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