JTable在arrayList中显示数据
这里用Java Eclipse编写代码。 制作预订系统。 我们的想法是从数据库中获取信息，将其存储在ArrayList中，并从ArrayList中通过JTable在GUI中显示它。 对最后一部分有一些问题而且无法弄明白.. ArrayList：
import java.util.ArrayList; public class CarList { private ArrayList cars; public CarList() { cars = new ArrayList(); } public int getNumberOfCars() { return cars.size(); } public Car getCar(String CarMake) { for (int i = 0; i < cars.size(); i++) { if (cars.get(i).getMake() == CarMake) { return cars.get(i); } } return null; } public int size() { return cars.size(); } public void add(Car car) { if (!this.ModelExists(car.getModel())) { cars.add(car); } } public Boolean ModelExists(String Model) { for (Car c : cars) { if (c.getModel().equals(Model)) { return true; } } return false; } public void remove(String CarMake) { for (int i = 0; i < cars.size(); i++) { if (cars.get(i).getMake() == CarMake) { cars.remove(i); } } } public String toString() { String returnStr = ""; for (int i = 0; i < cars.size(); i++) { Car temp = cars.get(i); returnStr += temp + "\n"; } return returnStr; } } 适配器将数据从db获取到arraylist：
public CarList getAllCars() { MyDatabase myDB = new MyDatabase(); CarList cars = new CarList(); try { myDB.openMySQLDatabase("db", "root", ""); String sql = "SELECT Make, Model, LicenseNumber, Color, Year," + "HorsePower, TimeUntilService, ConsumptionPerKm," + "NumberOfSeats, NumberOfDoors, Transmission, ClimateControl,Price " + "FROM cars"; System.out.println(sql); Object[][] result = myDB.returnSQLQueryResult(sql); for (int rows = 0; rows < result.length; rows++) { System.out.println("result row"); String make = (String) result[rows][0]; String model = (String) result[rows][1]; String licenseNumber = (String) result[rows][2]; String color = (String) result[rows][3]; int year = (int) result[rows][4]; String horsePower = (String) result[rows][5]; String timeUntilService = (String) result[rows][6]; String consumptionPerKm = (String) result[rows][7]; int numberOfSeats = (int) result[rows][8]; int numberOfDoors = (int) result[rows][9]; String transmission = (String) result[rows][10]; String climateControl = (String) result[rows][11]; int price = (int) result[rows][12]; cars.add(new Car(make, model, licenseNumber, color, year, horsePower, timeUntilService, consumptionPerKm, climateControl, numberOfSeats, numberOfDoors, transmission, climateControl, price)); } } catch (SQLException e) { e.printStackTrace(); } catch (ClassNotFoundException e) { e.printStackTrace(); } finally { try { myDB.closeDatabase(); } catch (SQLException e) { e.printStackTrace(); } } System.out.println(cars.size()); return cars; }
JTable的：
panelBottomRight = new JPanel(); panelBottomRight.setLayout(new BorderLayout()); panelBottomRight.setBorder(new TitledBorder(BorderFactory .createLineBorder(Color.black), "[Cars]", 2, 0)); tableBottomRightCenter = new JPanel(); tableBottomRightCenter.setLayout(new BorderLayout()); String[] columnNames = { "Make", "Model", "LicenseNumber", "Color", "Year", "HorsePower", "TimeUntilService", "ConsumptionPerKm", "NumberOfSeats", "NumberOfDoors", "ClimateControl" }; CarList cars= new CarList(); String[][] data = {}; // Create table with database data tableBottomR = new JTable(data, columnNames); tableBottomR.setAutoCreateRowSorter(true); tableBottomR.getTableHeader().setReorderingAllowed(false); tableBottomR.setModel(new DefaultTableModel(data, columnNames) { @Override public boolean isCellEditable(int rowIndex, int columnIndex) { return false; } }); tableBottomRightCenter.add(tableBottomR, BorderLayout.CENTER); scrollPane2 = new JScrollPane(tableBottomR); scrollPane2 .setHorizontalScrollBarPolicy(ScrollPaneConstants.HORIZONTAL_SCROLLBAR_NEVER); tableBottomRightCenter.add(scrollPane2); panelBottomRight.add(tableBottomRightCenter, BorderLayout.CENTER);
有一些事情会跳出来。
在您的CarList ， getCar方法正在比较对象引用，而不是比较String的内容
对于String比较，您应该使用String#equals ，例如……
public Car getCar(String CarMake) { for (int i = 0; i < cars.size(); i++) { //if (cars.get(i).getMake() == CarMake) { if (cars.get(i).getMake().equals(CarMake)) { return cars.get(i); } } return null; }
您似乎没有使用getAllCars方法填充表模型，而只是创建一系列空表模型。
就个人而言，我不是DefaultTableModel的粉丝，特别是考虑到你有一个Car对象和CarList对象，我会要求你撤消所有这些工作来使用它，相反，我更喜欢创建我自己的，专门的，实现，这使我能够提供更好的控制，例如......
public class CarModel extends AbstractTableModel { private String[] columnNames = { "Make", "Model", "LicenseNumber", "Color", "Year", "HorsePower", "TimeUntilService", "ConsumptionPerKm", "NumberOfSeats", "NumberOfDoors", "ClimateControl" }; private CarList carList; public CarModel(CarList list) { carList = list; } public CarList getCarList() { return carList; } @Override public int getRowCount() { return getCarList().getNumberOfCars(); } @Override public int getColumnCount() { return columnNames.length; } @Override public String getColumnName(int column) { return columnNames[column]; } @Override public Class getColumnClass(int columnIndex) { Class type = String.class; switch (columnIndex) { case 0: type = String.class; break; // ...etc... } return type; } @Override public Object getValueAt(int rowIndex, int columnIndex) { Car car = getCarList().getCarAt(rowIndex); Object value = null; switch (columnIndex) { case 0: value = car.getMake(); break; //...etc... } return value; } @Override public boolean isCellEditable(int rowIndex, int columnIndex) { return false; } }
显然，这将要求您向getCarAt(int)添加getCarAt(int)方法以返回给定索引处的Car 。
然后，您只需要从数据库中提取数据并将生成的CarList应用于表模型，例如......
CarList carList = getAllCars(); CarTableModel model = new CarTableModel(carList);
然后，您只需将其添加到您的UI，例如......
JTable table = new JTable(model); add(new JScrollPane(table));
看一下如何使用表格获取更多细节和示例......