I don't know how to set a button(or textfield) to expand to the whole space or shrink to minimal width of the button in a table-layout. For example:
TableLayout tl = new TableLayout(1,2);
Container Cnt = new Container(tl);
add(Cnt);
Button searchBtn = new Button("Expand or Shrink");
Cnt.add(tl.createConstraint().widthPercentage(80),searchBtn);
Sometimes searchBtn would expand to the whole space(80 percent of container's width), but others would shrink to the minimum width of searchBtn in a table-layout.
How do I expand or shrink a button in a table-layout as I wish?
And the expanding and shrinking rules of a button for in a BoxLayout.
The default behavior of a table layout is fill. If you add the button directly it will take up the 80 percent:
Cnt.add(tl.cc().wp(80), searchBtn);
If you need it to be in a container make sure not to use something like FlowLayout which grants it preferred size. Use something like the center of a border layout which grants the available size.
To make the button take the preferred size you can use a couple of other approaches. There are other constraints available as explained in the javadocs. There's also the common trick of nesting as you mentioned in the comment. E.g. for nesting:
Cnt.add(tl.cc().wp(80), FlowLayout.center(searchBtn));
Notice you can use other constraints in the flow layout to impact the alignment.
The second approach is to use the layout constraints:
Cnt.add(tl.cc().wp(80).ha(CENTER), searchBtn);