求大神解答这一道Java题 第20题 跪谢！

Java程序：

import java.awt.FlowLayout

import java.awt.event.ActionEvent

import java.awt.event.ActionListener

import javax.swing.JButton

import javax.swing.JComboBox

import javax.swing.JFrame

import javax.swing.JTextField

 

public class Main extends JFrame implements ActionListener {

    JComboBox cmbMenu_All, cmbMenu_Selected

    JButton btnAdd, btnRemove

    JTextField txtNum

    String[] menus = {"羊肉火锅", "狗肉火锅", "鱼仔火锅", "剁椒鱼头", "水煮活鱼",

     "柴火鱼", "酸辣鱼片", "茄子煲", "拨丝香蕉", "小炒肉",

     "小鸡炖蘑菇", "水煮肉片", "白斩鸡", "海带炖排骨", "熘丝瓜",

     "皮蛋煮苋菜", "醋溜土豆丝", 衡键世"梅菜扣肉", "香芋地瓜丸", "凉拌藕尖"}

     

    public Main() {

        super("点菜")        

        this.setLayout(new FlowLayout())

  咐肢      

        cmbMenu_All = new JComboBox(menus)

        cmbMenu_Selected = new JComboBox()

        btnAdd = new JButton(">>")

        btnRemove = new JButton("<<")

        txtNum = new JTextField(10)

        txtNum.setText("0")

        txtNum.setAlignmentX(CENTER_ALIGNMENT)

          

        this.add(cmbMenu_All)

        this.add(btnAdd)

        this.add(btnRemove)

      亮雹  this.add(cmbMenu_Selected)

        this.add(txtNum)

        

        btnAdd.addActionListener(this)

        btnRemove.addActionListener(this)

        

        this.setSize(400, 200)

        this.setVisible(true)

        this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE)

    }

     

    public static void main(String[] args) {

        new Main()

    }

@Override

public void actionPerformed(ActionEvent arg0) {

JButton btn = (JButton) arg0.getSource()

int num = Integer.parseInt(txtNum.getText().trim())

int i

if(btn == btnAdd) {

for(i=0 i<cmbMenu_Selected.getItemCount() i++) {

if(cmbMenu_Selected.getItemAt(i).toString().equals(cmbMenu_All.getSelectedItem().toString())) {

break

}

}

if(i < cmbMenu_Selected.getItemCount()) {

return

}

cmbMenu_Selected.addItem(cmbMenu_All.getSelectedItem())

num++

txtNum.setText(String.valueOf(num))

}

else if(btn == btnRemove) {

cmbMenu_Selected.removeItemAt(cmbMenu_Selected.getSelectedIndex())

num--

txtNum.setText(String.valueOf(num))

}

}

}

运行测试：

public

class

student{

private

string

stuid

private

string

stuname

private

char

stusex

private

int

stuage

/**

*以下是各属性的getter/setter方法

*/

public

void

setstuid(string

stuid){

this.stuid=stuid

}

public

string

getstuid(){

return

stuid

}

public

void

setstuname(string

stuname){

this.stuname=stuname

}

public

string

getstuname(){

return

stuname

}

public

void

setstusex(char

stusex){

this.stusex=stusex

}

public

char

getstusex(){

return

stusex

}

public

void

setstuage(int

stuage){

this.stuage=stuage

}

public

int

getstuage(){

return

stuage

}

/**

*构造方法，构造学生信息

*/

public

student(string

stuid,string

stuname,char

stusex,int

stuage){

this.stuid=stuid

this.stuname=stuname

this.stusex=stusex

this.stuage=stuage

}

public

string

tostring(){//覆盖该类的tostring()方法

stringbuffer

buff=new

stringbuffer()

buff.append("学号:"+stuid)

buff.append("\n姓名:"+stuname)

buff.append("\n性别:"+stusex)

buff.append("\n年龄:"+stuage)

return

buff.tostring()

}

public

static

void

main(string[]

args){

student

stu=new

student("郑好纳袜碧1000","zhangsan",'男',18)

system.out.println

(stu)//打印学生信息

system.out.println

("--修改姓名结果--"喊没)

stu.setstuname("lisi")

system.out.println

(stu)

}

}

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