Question

您好我无法将JTextField的值写入另一个类中的ArrayList，错误是“...字符串无法转换为Object”我该如何解决？这是arraylist类

public class MemberList
{
    private ArrayList < Member> members;

    /**
     * Create a Member. 
     */
    public MemberList()
    {
        members = new ArrayList < Member>();
    }

    /**
     * Add a member to this member list.
     * @param member the member to be added
     */
    public void addMember(Member member)
    {
        members.add(member);
    }
}

和GUI

 public class Test extends JFrame implements ActionListener {

    private JTextField jtFName, jtLName, jtMemberNo;
    private int nextMemNo;
    private MemberList members;
    private JFrame frame;

    @Override
    public void actionPerformed(ActionEvent evt) {
        members = new MemberList();

        if (evt.getActionCommand().equals("Add Member")) {
            if (jtLName.getText().equals("") && (jtFName.getText().equals(""))) {
                jtMember.setText("No names");
            } else if (jtFName.getText().equals("")) {
                jtMember.setText("No first name");
            } else if (jtLName.getText().equals("")) {
                jtMember.setText("No last name");
            } else if (!jtLName.getText().equals("") && (!jtFName.getText().equals(""))) {
                btnOne.setText("Confirm");

                String fName = jtFName.getText();
                String memNo = "1";
                String lName = jtLName.getText();
                members.addMember(member);

            }

        } else if (evt.getActionCommand().equals("No. of Members")) {
            btnTwo.setText("Clear Number");
            jlbMember.setVisible(true);

        } else if (evt.getActionCommand().equals("Clear Number")) {
            jtFName.setText("");
            jtLName.setText("");
        } else if (evt.getActionCommand().equals("Quit")) {
            System.exit(0);
        }
    }
}

在ArrayList中添加jtFName需要做什么？抱歉编辑错误，谢谢

Answer 1

您必须创建Member类的新实例并将其传递给addMember方法。例如

Member member = new Member(fName, lName); //replace with your actual constructor logic
members.addMember(member);

Answer 2

您的列表members包含Member类型的对象，而不是String类型

要么你的List包含String，就像： members = new ArrayList<String>();

或者为Member类创建一个构造函数，在该类中将String传递给对象，并将新的Object添加到List中：

public class Member{
  private String name;

  public Member(String name){ //create constructor with String argument
    this.name = name;
  }
}

members.addMember(new Member(name)) //add new Member to list

我看不到你的会员类，但是当我查看你的代码时，我认为它有一个fName，lName和memNo。所以在你的程序中构造函数看起来像：

public class Member{
  private String fName;
  private String lName;
  private String memNo;

  public Member(String fNamen, String lName, String memNo){ //create constructor with String arguments
    this.fName= fName;
    this.lName= lName;
    this.memNo= memNo;
  }
}

并将其添加到列表中，如：

members.addMember(new Member(fName, lName, memNo));

将JTextField值写入ArrayList

2 个答案: