java - 防止在Java中向JTable中添加重复数据

Question

如何防止向 Jtable 添加重复数据。

This is my code.

try {
    URL url = new URL("http://localhost:8080/webservice/rest/bdetails/get");
    HttpURLConnection conn = (HttpURLConnection) url.openConnection();
    conn.setRequestMethod("GET");
    conn.setRequestProperty("Accept", "application/json");

    if (conn.getResponseCode() != 200) {
        throw new RuntimeException("Failed : HTTP error code : "
            + conn.getResponseCode());
        }

        BufferedReader br = new BufferedReader(new InputStreamReader(
            (conn.getInputStream())));

        String output;
        String json = "";
        System.out.println("Output from Server .... \n");
        while ((output = br.readLine()) != null) {
            System.out.println(output);
                        json += output;
        }

        conn.disconnect();
        java.lang.reflect.Type listType = new TypeToken<ArrayList<BDetails>>() {
                }.getType();

        List<BDetails> bList = new Gson().fromJson(json, listType);

        for( BDetails adr : bList) 
        {
            DefaultTableModel model = (DefaultTableModel) pTable.getModel();
            Vector<String> row = new Vector<String>();
            row.add(detail.getUserName());
            row.add(detail.getFirstName());
            row.add(detail.getLastName());
            row.add(detail.getAddress();
            model.addRow( row );
        }
    } catch (IOException | RuntimeException ex) {
            System.out.println(ex);
        } 

当我运行此方法时，它将数据添加到表中。当我再次运行时，它将相同的数据添加到表中。它再次做同样的事情。我该如何解决这个问题？有谁能够帮助我？提前致谢。下面我添加了 BDetails 类。

BDetails Class

public class BDetails 
{
    private String username;
    private String firstName;
    private String lastName;
    private String address;

    public BDetails() {
    }

    public BDetails(String username, String firstName, String lastName, String address) {
        this.username = username;
        this.firstName = firstName;
        this.lastName = lastName;
        this.address = address;
    }

    public String getUsername() {
        return username;
    }

    public void setUsername(String username) {
        this.username = username;
    }

    public String getFirstName() {
        return firstName;
    }

    public void setFirstName(String firstName) {
        this.firstName = firstName;
    }

    public String getLastName() {
        return lastName;
    }

    public void setLastName(String lastName) {
        this.lastName = lastName;
    }

    public String getAddress() {
        return address;
    }

    public void setAddress(String address) {
        this.address = address;
    }

Answer 1

你可以试试这个，

        java.lang.reflect.Type listType = new TypeToken<ArrayList<BDetails>>() {
                }.getType();

        List<BDetails> bList = new Gson().fromJson(json, listType);

        DefaultTableModel model = (DefaultTableModel) pTable.getModel();
        model.setRowCount(0);

        for( BDetails adr : bList) 
        {

            Vector<String> row = new Vector<String>();
            row.add(detail.getUserName());
            row.add(detail.getFirstName());
            row.add(detail.getLastName());
            row.add(detail.getAddress();
            model.addRow( row );
        }

model.setRowCount(0) 将在插入数据之前清除所有行。它对我有用。