Java layout FlowLayout The size of the component when the layout is set

In the default JPanel, the FlowLayout layout is used

Here is the definition in the API:

JPanel (Boolean isdoublebuffered)
Creates a FlowLayout new with and specifies a buffering policy JPanel .

FlowLayout The layout Manager displays components, the component size is determined based on the preferredsize of the component,
And some components default to 0, so the release is not displayed,
Just give it a setpreferredsize.

For example:

JProgressBar pbar = new JProgressBar ();
Pbar.setminimum (min);
Pbar.setmaximum (max);
pbar.setpreferredsize (New Dimension (300, 25));
Add (Pbar);

The part that is marked in red is where you set the component size

Java layout FlowLayout The size of the component when the layout is set