java下拉框

1. java中怎麼獲取下拉框的值

方法/步驟

• 首先我們先創建一個下拉框：

  

2. java中，JComboBox下拉框選項事件。不同選項觸發不同事件

JComboBox jComboBox = new JComboBox(new Object[]{"選項1","選項2","選項3"});
panel.add(jComboBox);
jComboBox.addItemListener(new ItemListener() {
@Override
public void itemStateChanged(ItemEvent itemEvent) {

if(itemEvent.getStateChange()==1){
if(itemEvent.getItem()=="選項1"){
System.out.println("選項1輸出");
}else if(itemEvent.getItem()=="選項2"){
System.out.println("選項2輸出");
}{

}
}
}
});

3. java三個下拉框聯動

//:ComboBoxText.java
import java.awt.FlowLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.JComboBox;
import javax.swing.JFrame;

public class ComboBoxText {
private String[][] xxx = {
{"浙江","杭州","溫州","紹興","舟山",},
{"江蘇","南京","無錫","徐州","蒙矓",},
{"上海","閔行區","普陀區","金山區",},
};

private Object[] a(){
Object[] os = new Object[xxx.length];
for(int i=0; i<xxx.length; i++){
os[i]=xxx[i][0];
}
return os;
}

private Object[] b(Object a){
for(int i=0; i<xxx.length; i++){
if(xxx[i][0].equals(a)){
Object[] o = new Object[xxx[i].length-1];
for(int j=0; j<o.length; j++)
o[j]=xxx[i][j+1];
return o;
}
}
return new Object[]{};
}

public static void main(String[] args) {
final ComboBoxText ct = new ComboBoxText();
final JComboBox ca = new JComboBox(ct.a());
final JComboBox cb = new JComboBox();
ca.addActionListener(new ActionListener(){
public void actionPerformed(ActionEvent e) {
cb.removeAllItems();
Object selected = ca.getSelectedItem();
Object[] newItems = ct.b(selected);
for(int i=0; i<newItems.length; i++)
cb.addItem(newItems[i]);
}
});
ca.setSelectedIndex(-1);
JFrame f = new JFrame();f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
f.getContentPane().setLayout(new FlowLayout(FlowLayout.LEFT));
f.add(ca);f.add(cb);f.setVisible(true);
f.setSize(200,100);
}
}