这是功课。入门Java类。仍然把我的头缠在这东西上。
该项目是要建立一个库存管理系统。
除了如何使此按钮更改JTextField中的文本外，我已经弄清楚了一切。它需要从产品阵列（在本例中为DVD）中添加信息。这本书讨论了管理诸如JTextField的字体，位置和状态之类的不同方法，但是没有涉及格式化或调用文本的方法。
这是我要使用JTextArea进行操作的示例。从本质上讲，这就是我想对JTextField进行的操作。
...
// setup the interface
JPanel panel = new JPanel();
txt = new JTextArea(15,40);
txt.setEditable(false);//user shouldn't change it
panel.add(txt);
JButton next = new JButton("Next");
panel.add(next);
getContentPane().add(panel);
displayDVD();
}
// view software
public void displayDVD() {
txt.setText("DVD Details:\n");
txt.append("Item number: " + inv.get(currentDisplay).getItem() + "\n");
txt.append("DVD name: " + inv.get(currentDisplay).getName() + "\n");
txt.append("Units in stock: " + inv.get(currentDisplay).getUnits() + "\n");
txt.append("Price: $" +
String.format("%.2f",inv.get(currentDisplay).getPrice()) + "\n");
txt.append("Total value: $" +
String.format("%.2f",inv.get(currentDisplay).value()) + "\n");
txt.append("Fee: $" + String.format("%.2f",inv.get(currentDisplay).fee()) + "\n\n");
txt.append("Total value: $" + String.format("%.2f",inv.value()));
}
这是到目前为止我的实际代码
// GUI with navigation and file manipulation buttons
import javax.swing.*; // provides basic window features
import java.awt.event.*;
import java.awt.GridLayout;
import java.awt.BorderLayout;
public class AppGUI extends JFrame
{
private Inventory inv;
private int currentDisplay = 0;
private JPanel topButtonJPanel;
private JButton topButtons[];
private JPanel labelJPanel;
private JLabel labels[];
private JPanel fieldJPanel;
private JTextField fields[];
private JPanel buttonJPanel;
private JButton buttons[];
// LabelFrame constructor adds JLabels to JFrame
public AppGUI()
{
super( "Inventory Program v.5" );
setLayout( new BorderLayout() ); // set frame layout
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);// quit if the window is closed
// initialize values
RatedDVD d1 = new RatedDVD(1, "The Invisible Man", 0, 4999.99, "PG");
RatedDVD d2 = new RatedDVD(2, "The Matrix", 1, 13.01, "PG13");
RatedDVD d3 = new RatedDVD(3, "Se7en", 7, 11.11, "R");
RatedDVD d4 = new RatedDVD(4, "Oceans Eleven", 11, 9.02, "PG13");
RatedDVD d5 = new RatedDVD(5, "Hitch Hikers Guide to the Galaxy", 42, 10.00, "G");
// create inv and enter values
inv = new Inventory();
inv.add(d1);
inv.add(d2);
inv.add(d3);
inv.add(d4);
inv.add(d5);
inv.sort();
topButtons = new JButton[ 6 ]; // create topButtons array
topButtonJPanel = new JPanel(); // set up panel
topButtonJPanel.setLayout( new GridLayout( 1, topButtons.length, 2, 2 ) );
topButtons[0] = new JButton( "Load file" );
topButtons[1] = new JButton( "Add" );
topButtons[2] = new JButton( "Modify" );
topButtons[3] = new JButton( "Delete" );
topButtons[4] = new JButton( "Search" );
topButtons[5] = new JButton( "Save" );
for(int count=0;count<topButtons.length;count++){topButtonJPanel.add(topButtons[count]);}
//add( topButtonJPanel, BorderLayout.NORTH ); // this is for next weeks assignment
labels = new JLabel[8];
labelJPanel = new JPanel();
labelJPanel.setLayout( new GridLayout( labels.length, 1 ));
labels[0] = new JLabel( "Item ID" );
labels[1] = new JLabel( "Name" );
labels[2] = new JLabel( "Rating" );
labels[3] = new JLabel( "# in Stock" );
labels[4] = new JLabel( "Price" );
labels[5] = new JLabel( "Restocking Fee" );//[DEBUG] ref actual Variable
labels[6] = new JLabel( "Inventory Value with Fee (5%)" );
labels[7] = new JLabel( "Total Value with Fee(for all items)" );
for(int count=0;count<labels.length;count++){labelJPanel.add(labels[count]);}
add( labelJPanel, BorderLayout.WEST );
fields = new JTextField[8];
fieldJPanel = new JPanel();
int spaces = 28;
fieldJPanel.setLayout( new GridLayout( labels.length, 1 ));
fields[0] = new JTextField( "", spaces );
fields[1] = new JTextField( "", spaces );
fields[2] = new JTextField( "", spaces );
fields[3] = new JTextField( "", spaces );
fields[4] = new JTextField( "", spaces );
fields[5] = new JTextField( "", spaces );
fields[6] = new JTextField( "", spaces );
fields[7] = new JTextField( "", spaces );
for(int count=0;count<fields.length;count++)
{
fields[count].setEditable( false );
fieldJPanel.add(fields[count]);
}
add( fieldJPanel, BorderLayout.EAST );
buttons = new JButton[ 5 ]; // create buttons array
buttonJPanel = new JPanel(); // set up panel
buttonJPanel.setLayout( new GridLayout( 1, buttons.length, 2, 2 ) );
buttons[0] = new JButton( "First" );
buttons[0].addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
if (currentDisplay != 0)currentDisplay = 0; //advance to the end
}
});
buttons[1] = new JButton( "Prev" );
buttons[1].addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
if (currentDisplay != 0)currentDisplay--; //advance to the end
else currentDisplay = (inv.size()-1);
}
});
Icon bug1 = new ImageIcon( getClass().getResource( "bug1.gif" ) );
buttons[2] = new JButton( bug1 );
buttons[3] = new JButton( "Next" );
buttons[3].addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
if (currentDisplay < inv.size()-1)currentDisplay++; //advance to the end
else currentDisplay = 0; stkover
}});
buttons[4] = new JButton( "Last" );
buttons[4].addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
if (currentDisplay != inv.size()-1)currentDisplay = inv.size()-1; //advance to the end
else currentDisplay = (inv.size()-1);
}
});
for(int count=0;count<buttons.length;count++){buttonJPanel.add(buttons[count]);}
add( buttonJPanel, BorderLayout.SOUTH );
}// end method
}// end class AppGUI
任何提示提示或微调表示赞赏。不过请不要为我全部。
最佳答案
您向按钮添加了一个动作侦听器（以便它可以侦听按钮动作（单击））。然后对该动作进行编程以更改TextField值。
final JButton aButton = ...;
final JTextField aTextField = ...;
final String aNewText = "New TextField Value";
aButton.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
aTextField.setText(aNewText);
}
});
请注意，使用'actionPerformed'访问的变量必须是最终变量（字段除外）。
希望这可以帮助。