首先 ： 具体解释下 标题 下拉列表联动 就是将两个或两个以上的下拉列表连接（称作连接，后面就明白什么意思了）
简单的 例如
当我们点击别的省或市时
简而言之 就是实现下拉列表的联动
现在
除了基本的组件以外 希望大家先去了解一下 哈希map 以及下拉列表的部分方法
可以参考 http://c.biancheng.net/view/1225.html https://blog.csdn.net/weixin_44512194/article/details/92830703 这是下拉列表的方法
对于哈希 只要简单了解一下就好了 就不推荐网站了
好了 下面我们直接看代码
1 import java.awt.FlowLayout;
2 import java.awt.event.ItemEvent;
3 import java.awt.event.ItemListener;
4 import java.util.HashMap;
5 import javax.swing.JComboBox;
6 import javax.swing.JFrame;
7 import javax.swing.JLabel;
8 import javax.swing.WindowConstants;
9
10 public class JComboBoxExample extends JFrame implements ItemListener {
11
12
13 JLabel ProvinceJL;//Province label
14 JComboBox ProvinceJCB;//Province drop-down list
15 JLabel CityJL;//The city label
16 JComboBox CityJCB;//City drop-down list
17 JLabel DistrictAndCountyJL;//Area county label
18 JComboBox DistrictAndCountyJCB;//District and county drop-down list
19
20
21 //Set the corresponding hash
22 HashMap cont1;
23 HashMap cont2;
24 //Component defined
25
26 //A constructor
27 public JComboBoxExample(){
28 init();
29
30 }
31
32 private void init(){//Initialize the
33
34 //All levels of the label
35 ProvinceJL=new JLabel("省份：");
36 CityJL=new JLabel("市：");
37 DistrictAndCountyJL=new JLabel("区县：");
38
39
40 // The string array of provinces is set to three provinces and each unit has three cities under its jurisdiction
41 String [] ProOne={"安徽省","山东省","浙江省"};
42 //Three corresponding cities
43 String [] CityOne={"合肥市","芜湖市","安庆市"};
44 String [] CityTwo={"青岛市","济南市","菏泽市"};
45 String [] CityThree={"杭州市","宁波市","温州市"};
46
47 //Nine corresponding districts and counties
48 String [] DisOneOne={"包河区","长丰县","肥东县"};//安徽合肥
49 String [] DisOneTwo={"镜湖区","无为县","弋江区"};//安徽芜湖
50 String [] DisOneThree={"宿松县","怀宁县","太湖县"};//安徽安庆
51 String [] DisTwoOne={"崂山区","平度区","黄岛区"};//山东青岛
52 String [] DisTwoTwo={"长清区","槐荫区","平阴县"};//山东济南
53 String [] DisTwoThree={"单县","牡丹区","定陶区"};//山东菏泽
54 String [] DisThreeOne={"富阳区","西湖区","余杭区"};//浙江杭州
55 String [] DisThreeTwo={"北仑区","奉化区","宁海县"};//浙江宁波
56 String [] DisThreeThree={"苍南区","文成县","泰顺县"};//浙江温州
57
58 //The corresponding list of districts and counties mapped to different provinces and cities
59 cont1=new HashMap();
60 cont1.put(ProOne[0],CityOne);
61 cont1.put(ProOne[1],CityTwo);
62 cont1.put(ProOne[2],CityThree);//对省绑定市
63 //Bind county list to city
64 cont2=new HashMap();
65 cont2.put(CityOne[0],DisOneOne);
66 cont2.put(CityOne[1],DisOneTwo);
67 cont2.put(CityOne[2],DisOneThree);
68 cont2.put(CityTwo[0],DisTwoOne);
69 cont2.put(CityTwo[1],DisTwoTwo);
70 cont2.put(CityTwo[2],DisTwoThree);
71 cont2.put(CityThree[0],DisThreeOne);
72 cont2.put(CityThree[0],DisThreeTwo);
73 cont2.put(CityThree[0],DisThreeThree);
74 //Binding to all levels of the district and county completion
75 //Used for determination of subordinate drop-down lists
76
77
78 //All levels of tag instantiation
79 ProvinceJCB=new JComboBox(ProOne);
80 CityJCB=new JComboBox(CityOne);
81 DistrictAndCountyJCB=new JComboBox(DisOneOne);
82
83 //Add monitor
84 ProvinceJCB.addItemListener(this);
85 CityJCB.addItemListener(this);
86 DistrictAndCountyJCB.addItemListener(this);
87
88 //Set the size
89 setLayout(new FlowLayout());
90 setSize(500,550);
91
92 //add
93 add(ProvinceJL);
94 add(ProvinceJCB);
95 add(CityJL);
96 add(CityJCB);
97 add(DistrictAndCountyJL);
98 add(DistrictAndCountyJCB);
99
100 //show
101 setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE);
102 setVisible(true);
103 //Complete initialization
104 }
105
106
107 @Override//The event processing
108 public void itemStateChanged(ItemEvent e) {
109
110 String to=e.getItem().toString();
111 if (cont1.containsKey(to)){
112 //Provinces have been selected、
113 CityJCB.removeAllItems();
114 String [] now=cont1.get(to);
115 for(int i=0;i){
116 CityJCB.addItem(now[i]);
117 }
118 }
119 else {
120 if (cont2.containsKey(e.getItem().toString())){
121 DistrictAndCountyJCB.removeAllItems();
122 String [] now=cont2.get(to);
123 for(int i=0;i){
124 DistrictAndCountyJCB.addItem(now[i]);
125 }
126 }
127 }
128 }
129
130
131 public static void main(String [] args){
132 new JComboBoxExample();
133
134 }
135 }
如果你看了 上面的下拉列表的方法 相信你一定能看懂
就不多做解释了
Original: https://www.cnblogs.com/cndccm/p/12812301.html
Author: Mr小明同学
Title: javaGUI中下拉列表联动问题
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