36.微改进的计算器，JComboBox下拉框

public class SwingTest2 {

public static void main(String[] args) {
JFrame jFrame = new JFrame("计算器");

jFrame.setLayout(null );//绝对布局
final JTextField nub1Txt = new JTextField();
final JTextField nub2Txt = new JTextField();
final JTextField nub3Txt = new JTextField();
JButton jB = new JButton("=");
//JLabel fuHao =new JLabel("+" ,JLabel.CENTER);
String fuHao[] = {"+", "-", "*", "/"};
final JComboBox jcb = new JComboBox(fuHao);//下拉框,**注意**参数为fuHao非fuHao[]

nub1Txt.setBounds(10, 30,40,25);//绝对布局，组件摆放位置和大小
//fuHao.setBounds(80,40 , 10, 10);
jcb.setBounds(60,30 ,40, 25);
nub2Txt.setBounds(110, 30,50,25);//绝对布局，组件摆放位置和大小
jB.setBounds(170, 30, 50, 25);
nub3Txt.setBounds(230, 30, 50, 25);

//匿名监听类
jB.addActionListener(new ActionListener() {

public void actionPerformed(ActionEvent arg0) {
// TODO 自动生成的方法存根
String nub1 = nub1Txt.getText();//获取数字文本
String nub2 = nub2Txt.getText();//获取数字文本
String  algorithm = (String) jcb.getSelectedItem();//返回下拉框当前选项
int result = 0;//结果必须定义在这里，无法定义在if{}内，因为变量作用域的问题
if(algorithm.equals("+")){
result = Integer.pars
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eInt(nub1) + Integer.parseInt(nub2);
}
else if(algorithm.equals("-")){
result = Integer.parseInt(nub1) - Integer.parseInt(nub2);
}
else if (algorithm.equals("*")){
result = Integer.parseInt(nub1) * Integer.parseInt(nub2);
}
else if (algorithm.equals("/")){
result = Integer.parseInt(nub1) / Integer.parseInt(nub2);
}
//int result = Integer.parseInt(nub1) + Integer.parseInt(nub2);
nub3Txt.setText(String.valueOf(result));//显示文本
//nub3Txt.setText(result + "");//(result + "")与(String.valueOf(result)同效果，将int类型转换成String
}
});

jFrame.add(nub1Txt);
//jFrame.add(fuHao);
jFrame.add(jcb);
jFrame.add(nub2Txt);
jFrame.add(jB);
jFrame.add(nub3Txt);

jFrame.setLocation(300, 200);
jFrame.setSize(300, 150);
jFrame.setVisible(true);//让容器显示
jFrame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
}
}