我正在尝试制作一个简单的单位质量转换 GUI 应用程序。我有两个组合框可供选择单位，一个输入框输入要转换的数字，以及显示转换结果的文本。
我现在的问题是我正在尝试实际按下按钮来启动计算，但是当我从list下拉组合框中选择任何内容时它就会启动。我可以在文本框中输入一个数字，从第二个组合框中选择一个单位，然后从第一个组合框中选择一些东西，它会起作用，因为它有它需要的变量。
我的代码就在下面。
public class GuiApp{
JFrame frame;
JButton button;
JTextField field;
JLabel prompt,result,to;
JPanel contentpane;
JComboBox list,list2;
public GuiApp(){
frame = new JFrame("Mass Conversion Application");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
contentpane=new JPanel();
contentpane.setBorder(BorderFactory.createEmptyBorder(10,10,10,10));
String [] type={"Units", "Gram(s)","Kilogram(s)", "Pound(s)","Ounce(s)"};
list=new JComboBox(type);
list.setAlignmentX(JComboBox.LEFT_ALIGNMENT);
list.setSelectedIndex(0);
list.addActionListener(new converty());
contentpane.add(list);
to=new JLabel("to");
contentpane.add(to);
list2=new JComboBox(type);
list2.setAlignmentX(JComboBox.RIGHT_ALIGNMENT);
list2.setSelectedIndex(0);
list2.addActionListener(new converty());
contentpane.add(list2);
prompt=new JLabel("Enter here:");
prompt.setAlignmentX(JLabel.LEFT_ALIGNMENT);
contentpane.add(prompt);
field=new JTextField(10);
contentpane.add(field);
button=new JButton("Convert");
button.setAlignmentX(JButton.CENTER_ALIGNMENT);
button.setEnabled(false);
button.addActionListener(new converty());
button.setActionCommand("Convert");
contentpane.add(button);
result=new JLabel(" asdff ");
result.setAlignmentX(JLabel.CENTER_ALIGNMENT);
contentpane.add(result);
frame.pack();
frame.setVisible(true);
frame.setContentPane(contentpane);
}
class converty implements ActionListener{
public void actionPerformed(ActionEvent event){
if (!list.getSelectedItem().toString().equalsIgnoreCase("Units") && !list2.getSelectedItem().toString().equalsIgnoreCase("Units")){
button.setEnabled(true);
}
if (list.getSelectedItem().toString().equalsIgnoreCase(list2.getSelectedItem().toString()) && button.getActionCommand().equals("Convert")){
double thing=Double.parseDouble(field.getText());
result.setText(thing+" "+list.getSelectedItem().toString()+" is equal to "+thing+" "+list2.getSelectedItem().toString());
}
else if (list.getSelectedItem().toString().equalsIgnoreCase("Gram(s)") && !list2.getSelectedItem().toString().equalsIgnoreCase("Kilogram(s)") && button.getActionCommand().equals("Convert")){
double thing=Double.parseDouble(field.getText());
result.setText(thing+" "+list.getSelectedItem().toString()+" is equal to "+(thing/1000)+" "+list2.getSelectedItem().toString());
}
else if (list.getSelectedItem().toString().equalsIgnoreCase("Gram(s)") && !list2.getSelectedItem().toString().equalsIgnoreCase("Pound(s)") && button.getActionCommand().equals("Convert")){
double thing=Double.parseDouble(field.getText());
result.setText(thing+" "+list.getSelectedItem().toString()+" is equal to "+(thing*453.59237)+" "+list2.getSelectedItem().toString());
}
else if (list.getSelectedItem().toString().equalsIgnoreCase("Gram(s)") && !list2.getSelectedItem().toString().equalsIgnoreCase("Ounce(s)") && button.getActionCommand().equals("Convert")){
double thing=Double.parseDouble(field.getText());
result.setText(thing+" "+list.getSelectedItem().toString()+" is equal to "+(thing*28.349523125)+" "+list2.getSelectedItem().toString());
}
else if (list.getSelectedItem().toString().equalsIgnoreCase("Kilogram(s)") && !list2.getSelectedItem().toString().equalsIgnoreCase("Gram(s)") && button.getActionCommand().equals("Convert")){
double thing=Double.parseDouble(field.getText());
result.setText(thing+" "+list.getSelectedItem().toString()+" is equal to "+(thing*1000)+" "+list2.getSelectedItem().toString());
}
else if (list.getSelectedItem().toString().equalsIgnoreCase("Kilogram(s)") && !list2.getSelectedItem().toString().equalsIgnoreCase("Pound(s)") && button.getActionCommand().equals("Convert")){
double thing=Double.parseDouble(field.getText());
result.setText(thing+" "+list.getSelectedItem().toString()+" is equal to "+(thing/0.45359237)+" "+list2.getSelectedItem().toString());
}
else if (list.getSelectedItem().toString().equalsIgnoreCase("Kilogram(s)") && !list2.getSelectedItem().toString().equalsIgnoreCase("Ounce(s)") && button.getActionCommand().equals("Convert")){
double thing=Double.parseDouble(field.getText());
result.setText(thing+" "+list.getSelectedItem().toString()+" is equal to "+(thing/0.0283495231257)+" "+list2.getSelectedItem().toString());
}
else if (list.getSelectedItem().toString().equalsIgnoreCase("Ounce(s)") && !list2.getSelectedItem().toString().equalsIgnoreCase("Gram(s)") && button.getActionCommand().equals("Convert")){
double thing=Double.parseDouble(field.getText());
result.setText(thing+" "+list.getSelectedItem().toString()+" is equal to "+(thing*28.349523125)+" "+list2.getSelectedItem().toString());
}
else if (list.getSelectedItem().toString().equalsIgnoreCase("Ounce(s)") && !list2.getSelectedItem().toString().equalsIgnoreCase("Pound(s)") && button.getActionCommand().equals("Convert")){
double thing=Double.parseDouble(field.getText());
result.setText(thing+" "+list.getSelectedItem().toString()+" is equal to "+(thing/0.0625)+" "+list2.getSelectedItem().toString());
}
else if (list.getSelectedItem().toString().equalsIgnoreCase("Ounce(s)") && !list2.getSelectedItem().toString().equalsIgnoreCase("Kilogram(s)") && button.getActionCommand().equals("Convert")){
double thing=Double.parseDouble(field.getText());
result.setText(thing+" "+list.getSelectedItem().toString()+" is equal to "+(thing/0.0625)+" "+list2.getSelectedItem().toString());
}
else if (list.getSelectedItem().toString().equalsIgnoreCase("Ounce(s)") && !list2.getSelectedItem().toString().equalsIgnoreCase("Pound(s)") && button.getActionCommand().equals("Convert")){
double thing=Double.parseDouble(field.getText());
result.setText(thing+" "+list.getSelectedItem().toString()+" is equal to "+(thing/0.0625)+" "+list2.getSelectedItem().toString());
}
}
}
private static void GuiApp(){
JFrame.setDefaultLookAndFeelDecorated(true);
GuiApp greeting= new GuiApp();
}
public static void main(String[] args) {
javax.swing.SwingUtilities.invokeLater(new Runnable(){
public void run() {
GuiApp();
}
});
}
}