我在使用 JTables 时遇到问题 我知道我的代码有点难以理解，而且也有点困惑，因为它来自一个相当大的程序。是的，我刚刚了解了 Java 命名约定，其中变量不能以大写字母开头。
final JFrame Menu = new JFrame("Crime Database 2013");
Dimension screenSize0 = Menu.getToolkit().getScreenSize();
Menu.setBounds(screenSize0.width / 4, screenSize0.height / 4,
screenSize0.width / 2, screenSize0.height / 2);
Menu.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
Menu.setVisible(true);
JPanel options = new JPanel(new GridBagLayout());
GridBagConstraints a = new GridBagConstraints();
Menu.add(options);
JButton show = new JButton("Show all records");
a.gridx = 0;
a.gridy = 1;
options.add(show, a);
final JFrame Show = new JFrame("Crime Database 2013 - Show Records");
Dimension screenSize3 = Show.getToolkit().getScreenSize();
Show.setBounds(screenSize3.width/3 - 250, screenSize3.height/7,
screenSize3.width - 150, screenSize3.height-200);
Show.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
Show.setLayout(new GridBagLayout());
GridBagConstraints g = new GridBagConstraints();
final JPanel data = new JPanel(new FlowLayout());
JPanel sortselect = new JPanel(new GridBagLayout());
GridBagConstraints h = new GridBagConstraints();
g.gridx = 0;
g.gridy = 2;
Show.add(sortselect, g);
g.gridx = 0;
g.gridy = 0;
g.gridheight = 2;
g.gridwidth = 5;
Show.add(data, g);
JLabel label = new JLabel("Sort options");
JRadioButton none = new JRadioButton("No Sort",true);
JLabel frname = new JLabel("By First Name");
JRadioButton frnameup = new JRadioButton("First name - Alphabetical");
JRadioButton frnamedn = new JRadioButton("First name - Reverse-Alphabetical");
JLabel lsname = new JLabel("By Last Name");
JRadioButton lsnameup = new JRadioButton("Last name - Alphabetical");
JRadioButton lsnamedn = new JRadioButton("Last name - Reverse-Alphabetical");
JLabel byage = new JLabel("By Age");
JRadioButton ageup = new JRadioButton("Age - Increasing");
JRadioButton agedn = new JRadioButton("Age - Decreasing");
JLabel bycrime = new JLabel("By Crime");
JRadioButton crimeup = new JRadioButton("Crime - Alhabetically");
JRadioButton crimedn = new JRadioButton("Crime - Reverse-Alphabetical");
JLabel year = new JLabel("By Year of release");
JRadioButton yearup = new JRadioButton("Expected Year of Release - First");
JRadioButton yeardn = new JRadioButton("Expected Year of Release - Last");
ButtonGroup sortgroup = new ButtonGroup();
sortgroup.add(none);
sortgroup.add(frnameup);
sortgroup.add(frnamedn);
sortgroup.add(lsnameup);
sortgroup.add(lsnamedn);
sortgroup.add(ageup);
sortgroup.add(agedn);
sortgroup.add(crimeup);
sortgroup.add(crimedn);
sortgroup.add(yearup);
sortgroup.add(yeardn);
h.insets = new Insets(10,10,10,10);
h.gridx = 0;
h.gridy = 2;
sortselect.add(frname, h);
h.gridx = 0;
h.gridy = 3;
sortselect.add(frnameup, h);
h.gridx = 0;
h.gridy = 4;
sortselect.add(frnamedn, h);
h.gridx = 1;
h.gridy = 2;
sortselect.add(lsname, h);
h.gridx = 1;
h.gridy = 3;
sortselect.add(lsnameup, h);
h.gridx = 1;
h.gridy = 4;
sortselect.add(lsnamedn, h);
h.gridx = 2;
h.gridy = 2;
sortselect.add(byage, h);
h.gridx = 2;
h.gridy = 3;
sortselect.add(ageup, h);
h.gridx = 2;
h.gridy = 4;
sortselect.add(agedn, h);
h.gridx = 3;
h.gridy = 2;
sortselect.add(bycrime, h);
h.gridx = 3;
h.gridy = 3;
sortselect.add(crimeup, h);
h.gridx = 3;
h.gridy = 4;
sortselect.add(crimedn, h);
h.gridx = 4;
h.gridy = 2;
sortselect.add(year, h);
h.gridx = 4;
h.gridy = 3;
sortselect.add(yearup, h);
h.gridx = 4;
h.gridy = 4;
sortselect.add(yeardn, h);
h.gridwidth = 5;
h.gridheight = 1;
h.gridx = 0;
h.gridy =0;
sortselect.add(label, h);
h.gridx = 0;
h.gridy = 1;
sortselect.add(none, h);
show.addActionListener(
new ActionListener() {
public void actionPerformed(ActionEvent e1) {
Menu.setVisible(false);
int entries = 0;
BufferedReader lines = null;
try {
lines = new BufferedReader(new FileReader("L:\\workspace\\new java\\sources\\c-database.txt"));
} catch (FileNotFoundException e) {
e.printStackTrace();
}
try {
while (lines.readLine() != null) {
entries++;
}
} catch (IOException e2) {
e2.printStackTrace();
}
BufferedReader crimeinfo = null;
try {
crimeinfo = new BufferedReader(new FileReader("L:\\workspace\\new java\\sources\\c-database.txt"));
} catch (FileNotFoundException e) {
e.printStackTrace();
}
String namelist[] = new String[entries];
String agelist[] = new String[entries] ;
String crimelist[] = new String[entries];
String release[] = new String[entries];
for (int i = 0; i < entries; i++) {
String full = null;
try {
full = crimeinfo.readLine();
} catch (IOException e) {
e.printStackTrace();
}
String split[] = full.split(",");
namelist[i] = split[0];
agelist[i] = split[1];
crimelist[i] = split[2];
release[i] = split[3];
}
String firstnamelist[] = new String[entries];
String lastnamelist[] = new String[entries];
for (int i = 0; i < entries; i++) {
String namesplit[] = namelist[i].split(" ");
firstnamelist[i] = namesplit[0];
lastnamelist[i] = namesplit[1];
}
final String[] headers = {"First Name",
"Last Name",
"Age",
"Crime committed",
"Expected Year of Release"
};
final String[][] crimedata = new String[entries][5];
for (int i = 0; i < entries; i++) {
crimedata[i][0] = firstnamelist[i];
crimedata[i][1] = lastnamelist[i];
crimedata[i][2] = agelist[i];
crimedata[i][3] = crimelist[i];
crimedata[i][4] = release[i];
};
for (int i = 0; i < entries; i++) {
for (int j = 0; j < 5; j++) {
System.out.println(headers[j]);
System.out.println(crimedata[i][j]);
}
}
final JTable crimetable = new JTable(crimedata, headers);
JScrollPane scrollpane = new JScrollPane(crimetable);
crimetable.setAutoCreateRowSorter(true);
data.add(scrollpane);
Show.setVisible(true);
}
}
);
我只是将这段代码放入 eclipse 中，然后取出所有单选按钮，它就工作了。虽然我不知道为什么
最佳答案
JTable无法返回正确的Dimension或PreferredSize，有三种方法table.setPreferredScrollableViewportSize(table.getPreferredSize());但请注意 small JTables with a few Rows and Columns too要计算(部分)列和(部分)行的所需大小，然后以
table.setPreferredScrollableViewportSize(new Dimension(x, y) 形式传递此Dimension);覆盖
JScrollPane的getPreferredSize然后
JFrame.pack(before JFrame.setVisible(true))计算屏幕上所需的大小JPanel在API中实现了FlowLayout，我建议更改为BorderLayout，然后CENTER区域的JScrollPane可以填充整个(可用)区域并且将使用 JFrame 调整大小，无法调整 FlowLayout 放置的 JComponent(及其容器)的大小必须调用
data.revalidate()、data.repaint()和Show.pack()作为最后的代码行而不是(删除此代码行)Show.setVisible(true);将
Show重命名为myFrame，将show重命名为myButton
关于java - JTable 大小问题，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/16067350/