[問題] 一個 GridBagLayout 的問題

[Liszt04 (走路往下看都會怕)]

請問依下依個排版的問題


我希望排出這樣的排版
┌┬┬┬┬┐
├┴┴┴┴┤
├────┤
└────┘

上面是五個button, 中間是依個Jpanel可以畫畫, 下面是一個JTextField

code如下:




import javax.swing.*;
import java.awt.*;

public class GridBag extends JFrame
{
        private GridBagLayout layout;
        private GridBagConstraints constraints;

        private JButton button1;
        private JButton button2;
        private JComboBox combobox1;
        private JComboBox combobox2;
        private JCheckBox checkbox;
        private String list[] = {"option1", "option2", "option3", "option4"};

        private JPanel panel;

        private JTextField textarea;

        public GridBag()
        {
                super("gridbaglayout");
                layout = new GridBagLayout();
                setLayout(layout);
                constraints = new GridBagConstraints();


                button1 = new JButton("Button1");
                button2 = new JButton("Button2");
                combobox1 = new JComboBox(list);
                combobox2 = new JComboBox(list);
                checkbox = new JCheckBox("filled");

                textarea = new JTextField("textfield", 50);

                constraints.fill = GridBagConstraints.HORIZONTAL;
                addComponent(button1, 0, 0, 1, 1);
                addComponent(button2, 1, 0, 1, 1);
                addComponent(combobox1, 2, 0, 1, 1);
                addComponent(combobox2, 3, 0, 1, 1);
                addComponent(checkbox, 4, 0, 1, 1);

                constraints.fill = GridBagConstraints.BOTH;
                addComponent(panel, 0, 1, 5, 1);

                constraints.fill = GridBagConstraints.HORIZONTAL;
                addComponent(textarea, 0, 2, 5, 1);
        }

        public void addComponent(Component component, int column, int row, int
width, int height)
        {
                constraints.gridx = column;
                constraints.gridy = row;
                constraints.gridwidth = width;
                constraints.gridheight = height;

                layout.setConstraints(component, constraints);
                add(component);

        }

}




他跑出來的結果是:

exceptionx in thread "main" lava.lang.Nullpointerexception
        at java.util.Hastable.put(Hashtable.java:399)
        at java.awt.GridBagLayout.setConstraints(GridBagLayout.java:482)
        at GridBag.addComponent(GridBag.java:61)
        at GridBag.(init)(GridBag.java:48)
        at GridBagTest.main(GridBagTest.java:8)


這是GridBagTest的code:

mport javax.swing.*;
import java.awt.*;

public class GridBagTest
{
        public static void main(String args[])
        {
                GridBag g = new GridBag();
        g.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        g.setSize(600, 400);
        g.setResizable(false);
        g.setVisible(true);
        }
}

要是紅色部分沒有打的話 輸出是正確的

加上去panel之後整個跑不出來

add(panel) 換成add(button) 的話 排版竟然也是錯的 囧

請問一下是我哪邊寫錯了 還是我哪邊觀念不太正確

麻煩好心的大大幫我看一下吧

謝謝!

--
※ 發信站: 批踢踢實業坊(ptt.cc)
◆ From: 218.167.167.4
推 PsMonkey:那個 Exception 是在那一行爆出來的？ 至少標一下吧？
※ 編輯: Liszt04         來自: 218.167.167.4        (07/04 19:32)