question: public void addLayoutComponent ( String place , Component component ) { boolean isValid = true ; if ( place != null ) { if ( place . equals ( JSplitPane . DIVIDER ) ) { components [ 2 ] = component ; sizes [ 2 ] = getSizeForPrimaryAxis ( component . getPreferredSize ( ) ) ; } else if ( place . equals ( JSplitPane . LEFT ) || place . equals ( JSplitPane . TOP ) ) { components [ 0 ] = component ; sizes [ 0 ] = 0 ; } else if ( place . equals ( JSplitPane . RIGHT ) || place . equals ( JSplitPane . BOTTOM ) ) { components [ 1 ] = component ; sizes [ 1 ] = 0 ; } else if ( ! place . equals ( BasicSplitPaneUI . NON_CONTINUOUS_DIVIDER ) ) isValid = false ; } else { isValid = false ; } if ( ! isValid ) throw new IllegalArgumentException ( "cannot add to layout: " + "unknown constraint: " + place ) ; doReset = true ; }
target:  Adds the component at place.  Place must be one of JSplitPane.LEFT, RIGHT, TOP, BOTTOM, or null (for the divider).