如何用java實現(xiàn)下拉菜單

//核心代碼

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String[]?sg=?{"蘋果","香蕉","櫻桃","山楂"};

JComboBoxString?jcb?=?new?JComboBoxString(sg);

完整代碼

import?java.awt.*;

import?javax.swing.*;

public?class?MFrame?extends?JFrame{

public?MFrame()?{

String[]?sg=?{"蘋果","香蕉","櫻桃","山楂"};

JComboBoxString?jcb?=?new?JComboBoxString(sg);

add(jcb);

setLayout(new?FlowLayout());//把JFrame設(shè)置成流式布局

setTitle("測試");//設(shè)置窗口標題

setSize(220,?100);//設(shè)置窗口大小

setLocationRelativeTo(null);//設(shè)置窗口居中

setDefaultCloseOperation(EXIT_ON_CLOSE);//設(shè)置點擊關(guān)閉退出jvm虛擬機

setVisible(true);//設(shè)置窗口可見

}

public?static?void?main(String[]?args)?{

new?MFrame();//創(chuàng)建窗口

}

}

java程序下拉列表設(shè)計

效果圖

參考代碼

import java.awt.event.*;

import java.util.Vector;

import javax.swing.*;

public class Demo extends JFrame implements ActionListener {

JButton btn;

VectorString vector=new VectorString();

JComboBoxString jcb;

public Demo() {

vector.add("公斤");

vector.add("每個");

vector.add("每盒");

JLabel jl = new JLabel("單位");

jcb = new JComboBoxString(vector);//可以傳入一個數(shù)組或者一個Vector鏈表,對下拉框進行初始化

btn=new JButton("獲取下拉框的文字");

btn.addActionListener(this);

JPanel jp = new JPanel();

jp.add(jl);

jp.add(jcb);

jp.add(btn);

add(jp);

setSize(300, 200);

setLocationRelativeTo(null);

setTitle("下拉框Demo");

setDefaultCloseOperation(EXIT_ON_CLOSE);

}

public static void main(String[] args) {

new Demo().setVisible(true);

}

@Override

public void actionPerformed(ActionEvent e) {

JOptionPane.showMessageDialog(this, (String)jcb.getSelectedItem());

}

}

Java下拉框的整體代碼？

import java.awt.*;

import javax.swing.*;

public class DemoJframe extends JFrame {

private JPanel p1 = new JPanel(new BorderLayout());

private JComboBoxString jcb = new JComboBoxString();

public DemoJframe() {

jcb.insertItemAt("no.1", 0);

jcb.insertItemAt("no.2", 1);

jcb.insertItemAt("no.3", 2);

p1.add(jcb, BorderLayout.NORTH);

this.add(p1);

}

public static void main(String[] args) {

JFrame frame = new DemoJframe();

frame.setTitle("MyFrame");

frame.setSize(300, 300);

frame.setLocationRelativeTo(null);

frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

frame.setVisible(true);

}

}