java swt 下拉列表 java下拉列表框组件

package com.java.charpter13;

import java.awt.Container;
import java.awt.FlowLayout;
import java.util.concurrent.locks.AbstractOwnableSynchronizer;

import javax.swing.AbstractListModel;
import javax.swing.ComboBoxModel;
import javax.swing.JComboBox;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.WindowConstants;

public class JComBoxModelTest extends JFrame{
    private static final long serialVesionUID=1L;
    JComboBox<String> jc=new JComboBox<>(new MycomboBox());
    
    JLabel j1=new JLabel("请选择证件");
    
    
    public JComBoxModelTest()
    {
        setSize(160, 180);
        setVisible(true);
        setTitle("在窗口中设置下拉列表    ");
        
        setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE);
        Container cp=getContentPane();
        cp.setLayout(new FlowLayout());
        
        cp.add(j1);
        cp.add(jc);
        
        
        
        
        
    }
    public static void main(String[] args) {
        new JComBoxModelTest();
    }
}

class MycomboBox extends AbstractListModel<String> implements ComboBoxModel<String>
{
    String selecteditem=null;
    String[] test={"身份证","军人证","学生证","工作证"};
    

    @Override
    public int getSize() {
        // TODO Auto-generated method stub
        return test.length;
    }

    @Override
    public String getElementAt(int index) {
        // TODO Auto-generated method stub
        return test[index];
    }

    @Override
    public void setSelectedItem(Object anItem) {
        selecteditem=(String) anItem;
        
    }

    @Override
    public Object getSelectedItem() {
        // TODO Auto-generated method stub
        return selecteditem;
    }
    
    public int getIndex() {
        for (int i = 0; i < test.length; i++) {
            if (test[i].equals(getSelectedItem()))
                return i;
        }
        return 0;
    }
    
    
    

}