我是根据书上关于MVC结构的示例改写成商品结账系统的，书上的示例运行后的窗口如下图。（接下来，我放的东西有点多，额。。算是一个仿写代码的过程吧，看了以后可以防雷吧）书上的示例代码如下：Example10_15.java
public class Example10_15 {
public static void main(String args[]){
WindowTriangle win = new WindowTriangle();
win.setTitle("使用MVC结构");
win.setBounds(100,100,420,260);
}
}
WindowTriangle.java
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
public class WindowTriangle extends JFrame implements ActionListener {
Triangle triangle; //模型
JTextField textA,textB,textC; //视图
JTextArea showArea; //视图
JButton controlButton; //控制器
WindowTriangle() {
init();
setVisible(true);
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
}
void init() {
triangle = new Triangle();
textA = new JTextField(5);
textB = new JTextField(5);
textC = new JTextField(5);
showArea = new JTextArea();
controlButton=new JButton("计算面积");
JPanel pNorth=new JPanel();
pNorth.add(new JLabel("边A:"));
pNorth.add(textA);
pNorth.add(new JLabel("边B:"));
pNorth.add(textB);
pNorth.add(new JLabel("边C"));
pNorth.add(textC);
pNorth.add(controlButton);
controlButton.addActionListener(this);
add(pNorth,BorderLayout.NORTH);
add(new JScrollPane(showArea),BorderLayout.CENTER);
}
public void actionPerformed(ActionEvent e) {
try{
double a = Double.parseDouble(textA.getText().trim());
double b = Double.parseDouble(textB.getText().trim());
double c = Double.parseDouble(textC.getText().trim());
triangle.setA(a) ; //更新数据
triangle.setB(b);
triangle.setC(c);
String area = triangle.getArea();
showArea.append("三角形"+a+","+b+","+c+"的面积:");
showArea.append(area+"\n"); //更新视图
}
catch(Exception ex) {
showArea.append("\n"+ex+"\n");
}
}
}
Triangle.java
public class Triangle {
double sideA,sideB,sideC,area;
boolean isTriange;
public String getArea() {
if(isTriange) {
double p = (sideA+sideB+sideC)/2.0;
area = Math.sqrt(p*(p-sideA)*(p-sideB)*(p-sideC)) ;
return String.valueOf(area);
}
else {
return "无法计算面积";
}
}
public void setA(double a) {
sideA = a;
if(sideA+sideB>sideC&&sideA+sideC>sideB&&sideC+sideB>sideA)
isTriange = true;
else
isTriange = false;
}
public void setB(double b) {
sideB = b;
if(sideA+sideB>sideC&&sideA+sideC>sideB&&sideC+sideB>sideA)
isTriange = true;
else
isTriange = false;
}
public void setC(double c) {
sideC = c;
if(sideA+sideB>sideC&&sideA+sideC>sideB&&sideC+sideB>sideA)
isTriange = true;
else
isTriange = false;
}
}我自己改编的代码如下：//Example10_15.java
public class Example10_15
{
public static void main(String args[])
{
WindowStringBuffer win = new WindowStringBuffer();
win.setTitle("使用MVC结构");
win.setBounds(100,100,420,260);
}
}
//WindowStringBuffer.java
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
public class WindowStringBuffer extends JFrame implements ActionListener
{
StringBuffer stringBuffer; //模型
JTextField textA,textB,textC,textD,textF; //视图
JTextArea showArea ; //视图
JButton controlButton; //控制器
WindowStringBuffer()
{
init();
setVisible(true);
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
}
void init()
{
stringBuffer = new StringBuffer();
textA = new JTextField(5);
textB = new JTextField(5);
textC = new JTextField(5);
textD = new JTextField(5);
textF = new JTextField(5);
showArea = new JTextArea();
controlButton=new JButton("录入商品信息");
JPanel pNorth=new JPanel();
pNorth.add(new JLabel("商品编号:"));
pNorth.add(textA);
pNorth.add(new JLabel("商品名称:"));
pNorth.add(textB);
pNorth.add(new JLabel("商品产地："));
pNorth.add(textC);
pNorth.add(new JLabel("商品单价："));
pNorth.add(textD);
pNorth.add(new JLabel("商品数量："));
pNorth.add(textF);
pNorth.add(controlButton);
controlButton.addActionListener(this); //设置监视器
add(pNorth,BorderLayout.NORTH);
add(new JScrollPane(showArea),BorderLayout.CENTER);
}
public void actionPerformed(ActionEvent e) //动作执行
{
try{
int a = int.parseInt(textA.getText().trim());
String b = String.parseString(textB.getText().trim());
String c = String.parseString(textC.getText().trim());
double d = Double.parseDouble(textD.getText().trim());
int f = int.parseInt(textF.getText().trim());
stringBuffer.setGoodNum(a); //更新数据
stringBuffer.setGoodName(b);
stringBuffer.setGoodArea(c);
stringBuffer.setGoodValue(d);
stringBuffer.setGoodSum(f);
String information = stringBuffer.showInformation();
showArea.append("商品编号:"+a+","+"商品名称:"+b+","+"商品产地:"+c+","+"商品价格:"+d+","+"商品数量:"+f);
showArea.append(information+"\n"); //更新视图
}
catch(Exception ex)
{
showInformation.append("\n"+ex+"\n");
}
}
}
//StringBuffer.java
public class StringBuffer
{
int goodNum,goodSum;
double goodValue;
String goodName,goodArea;
public String getInformation()
{
stringBuffer.showInformation();
public setGoodNum(int a)
{
goodNum = a;
return a;
}
public setGoodName(string b)
{
goodName = b;
return b;
}
public setGoodArea(string c)
{
goodArea= c;
return c;
}
public setGoodValue(double d)
{
goodValue = d;
return d;
}
public setGoodSum(int f)
{
goodSum = f;
return f;
}
}心痛2017....我不知道我改的代码错在哪。。。难道显示商品属性不能用StringBuffer类做吗？！！请大神指教也欢迎小伙伴前来讨论！
15 回答
看风景非凡
TA贡献9条经验 获得超11个赞
额，你这代码错误太多了。。
int只是基本数据类型，哪来parseInt()方法（Integer）.
String有这个parseString()方法吗？
后面那些set方法每一个都没返回类型，而且直接return就行，还赋值干嘛。
还有好多错
先打好基础吧。
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