JComboBox actionListener 不起作用

Question

我有一个有 4 个私有属性的类，通过一个 JComboBox 选择，我想通过调用一个过程来修改它们。但是，似乎即使 JComboBox 与选择一起出现，显示的属性也不会改变。

public class PanneauVehicule extends JPanel {


private String[] vehicules;
private int majCarburant;
private int majPassager;


public class PanneauVehicule extends JPanel {
//Main constructor
   public PanneauVehicule(){
       //Creates a JPanel
       super();
       //Sets layout as BorderLayout
       setLayout(new BorderLayout());
       initListeVehicule();
       initLabels();
    }
 public void initListeVehicule(){

    vehicules = new String[] {Constantes.CS100 , Constantes.CS300 , 
            Constantes.GREYHOUND102D3 , Constantes.GREYHOUNDG4500 , 
            Constantes.TGVATLANTIQUE , Constantes.TGVDUPLEX};

    final JComboBox<String> vehiculesList = new JComboBox<>(vehicules);
    //Keep in mind the comboBox does appear with the right selections
    add(vehiculesList,BorderLayout.NORTH);
    //Here's where it doesnt work.
    vehiculesList.addActionListener(new ActionListener() {
        public void actionPerformed(ActionEvent e){
            majInfo(2,4);
        }
    });
}
public void majInfo(int test1, int test2){
    this.majCarburant = test2;
    this.majPassager = test1;
}

public void initLabels(){

    JPanel panneauBas = new JPanel();
    panneauBas.setLayout(new GridLayout(2,1,5,5));

    JLabel labelCarburant = new JLabel();
    labelCarburant.setText("Type de caburant: " + this.majCarburant);

    JLabel labelPassagers = new JLabel();
    labelPassagers.setText("Nb de passagers: " + this.majPassager);

    panneauBas.add(labelPassagers);
    panneauBas.add(labelCarburant);

    add(panneauBas, BorderLayout.SOUTH);
    panneauBas.setBackground(Color.WHITE);
}

之后，我使用另一个程序使 majCarburant 和 majPassager 出现在屏幕上。但是，它们的值显示为默认值 (0)。我可以在不使用 ActionListener 的情况下手动更改它们的值，但手头的任务需要我使用一个。

Answer 1

我一直在尝试直接通过 actionListener 更改值的方法，

您不直接调用 ActionListener。将 ActionListener 添加到组合框后，您可以调用：

1. setSelectedItem(...) 或
2. setSelectedIndex(...)

在组合框上，组合框将调用ActionListener。

Answer 2

经过几个小时的干预，我找到了解决方案。我刚刚将创建标签的过程集成到 initListeVehicule 中，ActionListener 可以从那里访问标签以修改其文本。

public void initListeVehiculeInfos(){

    vehicules = new String[] {Constantes.CS100 , Constantes.CS300 , 
            Constantes.GREYHOUND102D3 , Constantes.GREYHOUNDG4500 , 
            Constantes.TGVATLANTIQUE , Constantes.TGVDUPLEX};

    final JComboBox<String> vehiculesList = new JComboBox<>(vehicules);
    add(vehiculesList,BorderLayout.NORTH);

    JPanel panneauBas = panelGenerator();
    //these setTexts serve as default values before doing your first selection

    final JLabel carb = labelGenerator();
    carb.setText("Carburant: Kérosène");

    final JLabel passager = labelGenerator();
    passager.setText("Nb Passager: 110");


    vehiculesList.addActionListener(new ActionListener() {
        public void actionPerformed(ActionEvent e){
            InterfaceVehicules info = FabriqueVehicule.obtenirVehicule(vehiculesList.getSelectedIndex());
            carb.setText("Carburant: " + info.tabNomTypeCarburant[info.getTypeCarburant()] );
            passager.setText("Nb Passagers: " + info.getNbPassagersMax());
        }
    });

    panneauBas.add(carb);
    panneauBas.add(passager);

    add(panneauBas, BorderLayout.SOUTH);

}