关于布局问题？

Question

这个一般的书上太多了吧，

Answer 1

那去看，很全的import java.awt.*;
   
public class LayoutApp extends Frame
{
MenuBar menuBar;
Panel panels[];
Panel currentPanel;
static int border=0;
static int card=1;
static int flow=2;
static int grid=3;
static int gridBag=4;
Menu cardMenu;
public static void main(String[] args)
{
LayoutApp app=new LayoutApp();
}
public LayoutApp()
{
setup();
resize(400,400);
show();
}
void setup()
{
setupMenuBar();
setupPanels();
}
void setupMenuBar()
{
menuBar=new MenuBar();
Menu fileMenu=new Menu("File");
fileMenu.add(new MenuItem("Exit"));
menuBar.add(fileMenu);

Menu panelMenu=new Menu("Panel");
panelMenu.add(new MenuItem("BorderLayout"));
panelMenu.add(new MenuItem("CardLayout"));
panelMenu.add(new MenuItem("FlowLayout"));
panelMenu.add(new MenuItem("GridLayout"));
panelMenu.add(new MenuItem("GridBagLayout"));
menuBar.add(panelMenu);

cardMenu=new Menu("Card");
cardMenu.add(new MenuItem("First"));
cardMenu.add(new MenuItem("Last"));
cardMenu.add(new MenuItem("Next"));
cardMenu.add(new MenuItem("Previous"));

setMenuBar(menuBar);
}
void setupPanels()
{
panels=new Panel[5]; for (int i=0;i<5;++i) panels[i]=new Panel();
panels[border].setLayout(new BorderLayout());
panels[card].setLayout(new CardLayout());
panels[flow].setLayout(new FlowLayout());
panels[grid].setLayout(new GridLayout(3,3));

GridBagLayout gridBagLayout=new GridBagLayout();
panels[gridBag].setLayout(gridBagLayout); //Set BorderLayout:
panels[border].add("North",new Button("North"));
panels[border].add("South",new Button("South"));
panels[border].add("East",new Button("East"));
panels[border].add("West",new Button("West"));
panels[border].add("Center",new Button("Center"));

String cardButtons[]={"First","Second","Third","Fourth","Last"};
String flowButtons[]={"One","Two","Three","Four","Five"};
String gridButtons[]={"(0,0)","(1,0)","(2,0)","(0,1)","(1,1)","(2,1)","(3,1)","(2,1)","(3,1)"};

for (int i=0;i<cardButtons.length;++i)
panels[card].add(cardButtons[i],new Button(cardButtons[i]));
for (int i=0;i<flowButtons.length;++i)
panels[flow].add(new Button(flowButtons[i]));
for (int i=0;i<gridButtons.length;++i)
panels[grid].add(new Button(gridButtons[i]));
Button gridBagButtons[]=new Button[9];
for (int i=0;i<9;++i)
gridBagButtons[i]=new Button("Button"+i);

int gridx[]={0,1,2,0,2,0,1,1,8};
int gridy[]={0,0,0,1,1,2,2,3,6};
int gridwidth[]={1,1,1,2,1,1,1,2,3};
int gridheight[]={1,1,1,1,2,2,1,1,1};

GridBagConstraints gridBagConstraints[]=new GridBagConstraints[9];
for (int i=0;i<9;++i)
{
gridBagConstraints[i]=new GridBagConstraints();
gridBagConstraints[i].fill=GridBagConstraints.BOTH;
gridBagConstraints[i].gridx=gridx[i];
gridBagConstraints[i].gridy=gridy[i];
// gridBagConstraints[i].gridwidth=gridwidth[i];
// gridBagConstraints[i].gridheight=gridheight[i];
gridBagLayout.setConstraints(gridBagButtons[i],gridBagConstraints[i]);
panels[gridBag].add(gridBagButtons[i]);

}
// add("Center",panels[border]);
add(panels[border]);
currentPanel=panels[border];
}

public boolean handleEvent(Event e)
{
if (e.id==Event.WINDOW_DESTROY)
{
System.exit(0);
return true;
}
else
if (e.id==Event.ACTION_EVENT)
{
if (e.target instanceof MenuItem)
{
if ("Exit".equals(e.arg))
{
System.exit(0);
return true;
}
if ("BorderLayout".equals(e.arg))
{
switchPanels(panels[border],"BorderLayout",false);
return true;
}
if ("CardLayout".equals(e.arg))
{
switchPanels(panels[card],"CardLayout",true);
return true;
}
if ("FlowLayout".equals(e.arg))
{
switchPanels(panels[flow],"FlowLayout",false);
return true;
}
if ("GridLayout".equals(e.arg))
{
switchPanels(panels[grid],"GridLayout",false);
return true;
}
if ("GridBagLayout".equals(e.arg))
{
switchPanels(panels[gridBag],"GridBagLayout",false);
return true;
}
if ("First".equals(e.arg))
{
CardLayout currentLayout=(CardLayout)currentPanel.getLayout();
currentLayout.first(currentPanel);
return true;
}
if ("Next".equals(e.arg))
{
CardLayout currentLayout=(CardLayout)currentPanel.getLayout();
currentLayout.next(currentPanel);
return true;
}
if ("Last".equals(e.arg))
{
CardLayout currentLayout=(CardLayout)currentPanel.getLayout();
currentLayout.last(currentPanel);
return true;
}
if ("Previous".equals(e.arg))
{
CardLayout currentLayout=(CardLayout)currentPanel.getLayout();
currentLayout.previous(currentPanel);
return true;
}
}
}
return false;
}
void switchPanels(Panel newPanel,String newTitle,boolean setCardMenu)
{
remove(currentPanel);
currentPanel=newPanel;
add(currentPanel);
setTitle(newTitle);
if (setCardMenu) 
menuBar.add(cardMenu);
else
menuBar.remove(cardMenu);
show();
}
}