如果JComboBox是可编辑的，如何将输入的字符串强制转换为object？

Question

所以我有这个类“成员”：

package pkgData;

import java.io.Serializable;

public class Member implements Comparable<Member>, Serializable{
  /**
  * 
  */
  private static final long serialVersionUID = 1L;
  private String name;
  private String city;

  public Member(String nameOfMember,String location) {
      super();
      this.name = nameOfMember;
      this.city=location;
  }


  public String getNameOfMember() {
      return name;
  }

  public String getLocationOfMember() {
      return city;
  }

  public void setNameOfMember(String nameOfMember) {
      this.name = nameOfMember;
  }


  @Override
  public String toString() {
      return name +", " + city;
  }


  @Override
  public int compareTo(Member o) {
      int result =this.getNameOfMember().compareTo(o.getNameOfMember());

      if(result==0){
          result = this.getLocationOfMember().compareTo(o.getLocationOfMember());
      }

      return result;
  }



}

我有一个可编辑的JComboBox，ComboBox的模型是DefaultComboBoxModel。

所以问题是如果我强制转换selectedItem:

Member nameOfMember = (Member)memberModel.getSelectedItem();            
    if(nameOfMember== null)
        throw new Exception("please select a name and a location"); 

它只检查输入的字符串是否为空。如果我输入一个类似“Name，Location”的字符串，我总是得到一个异常，即字符串不能转换为成员。我必须输入哪个字符串才能将该字符串转换为成员？

这是我的JComboBox：

private JComboBox<Member> getComboBoxMember() {
    if (comboBoxMember == null) {
        comboBoxMember = new JComboBox<Member>();
        comboBoxMember.setEditable(true);
        comboBoxMember.setModel(memberModel);
    }
    return comboBoxMember;
}

这里是全局变量：

private DefaultComboBoxModel<Member> memberModel;
private JComboBox<Member> comboBoxMember;

Answer 1

字符串拆分

你能做的是首先测试你得到的字符串是否为空，或者它是否与你的格式匹配。然后，您可以用这些元素创建一个新的对象。

下面是一个小示例代码：

String memberData = (String)memberModel.getSelectedItem();
if(memberData == null || memberData.split(", ")[0].isEmpty() || memberData.split(", ")[1].isEmpty()) {
    throw new Exception("Data is incorrect, please provide name and location separated with ", ");
}
Member member = new Member(memberData.split(", ")[0], memberData.split(", ")[1]);

JComboBox方法

随着Java 7的出现，扩展到JComboBox的新可能性，现在可以以JComboBox的形式进行通用参数化（如ArrayLists）。

您可以在监听器方法(我将使用< code>ActionListener)中执行以下操作:

class ItemAction implements ActionListener {
    @Override
    public void actionPerformed(ActionEvent e) {
        try {
            //In case the user has not modified the object
            Member member = (Member)box.getSelectedItem();
            //Just an example here
            if(member != null) {
                System.out.println(member.toString());
            }
        } catch(ClassCastException ex) {
            //In case the object has been modified
            String data = (String)box.getSelectedItem();
            //Apply first method here
        }

    }
}

但这种方法的问题是你最终仍然使用第一种方法。

Answer 2

String nameOfMember = (String) memberModel
        .getSelectedItem();if(nameOfMember==null)throw new Exception("please select a name and a location");else

{
String[] parts = nameOfMember.split(",");
String part1 = parts[0]; // name
String part2 = parts[1]; // location
Member member=new Member(part1, part2);
}