java - 我想从两个 ComboBox 中选择 NAME 和 FILM 并将所选项目放入 H2 DB 中

Question

我从 h2 db 中填写了两个组合框。在组合框中你只能看到名称。我怎样才能从组合框中获取所选项目的 ID？并通过id来写入新的executeQuery

JComboBox<String> comboBox = new JComboBox<>();
    try {
        String sql="SELECT clientid,name,lastname FROM client";
        conn = DBConnector.getConnection();
        state = conn.prepareStatement(sql);
        result = state.executeQuery();
        while(result.next()) {
            String name = result.getString("name");
            String lname = result.getString("lastname");
            comboBox.addItem(name+" "+lname);

        }

    } catch (Exception e) {
        e.printStackTrace();
    }
    comboBox.setBounds(10, 91, 146, 22);
    contentPane.add(comboBox);
JComboBox<String> comboBox_1 = new JComboBox<>();

    try {
        String sql="SELECT title,yearpub FROM films";
        conn = DBConnector.getConnection();
        state = conn.prepareStatement(sql);
        result = state.executeQuery();
        while(result.next()) {
            String name = result.getString("title");
            String year = result.getString("yearpub");
            comboBox_1.addItem(name+" "+year);

        }

    } catch (Exception e) {
        e.printStackTrace();
    }
    comboBox_1.setBounds(194, 91, 146, 22);
    contentPane.add(comboBox_1);

Answer 1

您仅将名字和姓氏添加到您发布的这行代码中的第一个 JComboBox 中:

comboBox.addItem(name+" "+lname);

ID 未存储在 JComboBox 模型中，因此不在所选项目中。

默认情况下，JComboBox 显示其模型中对象的方法 toString() 返回的 String，因此一个简单的解决方案是创建自定义类和自定义 toString() 方法。例如，对于第一个 JComboBox:

public class Client {
    private int id;
    private String name;
    private String lname;

    public Client(int id, String name, String lname) {
        this.id = id;
        this.name = name;
        this.lname = lname;
    }

    public int getId() {
        return id;
    }

    public String toString() {
        return name + " " + lname;
    }
}

然后您创建并填充一个 JComboBox，如下所示:

JComboBox<Client> comboBox = new JComboBox<>();
try {
    String sql="SELECT clientid,name,lastname FROM client";
    conn = DBConnector.getConnection();
    state = conn.prepareStatement(sql);
    result = state.executeQuery();
    while(result.next()) {
        int id = result.getInt("clientid");
        String name = result.getString("name");
        String lname = result.getString("lastname");
        comboBox.addItem(new Client(id, name, lname));
    }
} catch (Exception e) {
    e.printStackTrace();
}

现在，当您调用 JComboBox 中的 getSelectedItem() 方法时，它将返回一个包含 ID 的 Client 对象。

Object obj = comboBox.getSelectedItem();
Client client = (Client) obj;
int id = client.getId();

请注意，Client 类的 toString() 方法意味着 JComboBox 将仅显示 name 和 lname。