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1.使用Java图形界面组件设计软件，界面如图所示。
2.软件能够满足基本的“加、减、乘、除”等运算要求。
3.程序代码清晰，语法规范，结构合理，逻辑正确。
效果图：
先分析，计算器大概是由三个大部分组成的：菜单栏，显示框，按钮。
所以定义一个类cal继承JFrame。
class cal extends JFrame {
private JPanel p1, p2;
private JTextArea show;
private String box ;
JMenuBar menubar;//菜单
JMenu menu1, menu2, menu3;//菜单
StringBuffer strA;//用来存放用户输入的第一个数字
StringBuffer strB;//用来存放用户输入的第二个数字
char oper ='~';//初始化操作符，可以随便初始化一个特殊符号，这里只是用来区分的
double A;
double B;
private String[] text2 = {"C", "CE","%", "/",
"7", "8", "9", "*",
"4", "5", "6", "-",
"1", "2", "3", "+",
"DEL","0", ".", "="};//计算器按钮面板
private JButton[] munButton = new JButton[text2.length];
}我们定义完后开始初始化。
class cal extends JFrame implements ActionListener {
private JPanel p1, p2;
private JTextArea show;
private String box ;
JMenuBar menubar;
JMenu menu1, menu2, menu3;
StringBuffer strA;
StringBuffer strB;
char oper ='~';
double A;
double B;
private String[] text2 = {"C", "CE","%", "/",
"7", "8", "9", "*",
"4", "5", "6", "-",
"1", "2", "3", "+",
"DEL","0", ".", "="};//计算器按钮面板
private JButton[] munButton = new JButton[text2.length];
public cal() {
p1 = new JPanel();
p2 = new JPanel();
show = new JTextArea();
p1.setSize(600, 100);
menubar = new JMenuBar();
menu1 = new JMenu("查看(V)");
menu2 = new JMenu("编辑(E)");
menu3 = new JMenu("帮助(H)");
strB=new StringBuffer();
strA=new StringBuffer();
}
public void init() {//初始化
this.setTitle("计算器");//设置名称
this.setBounds(200, 200, 320, 300);
this.setLayout(new BorderLayout());//设置布局
this.add(p1, BorderLayout.CENTER);
this.add(p2, BorderLayout.SOUTH);
menubar.add(menu1);
menubar.add(menu2);
menubar.add(menu3);
this.setJMenuBar(menubar);
this.setLocationRelativeTo(null);//放置在屏幕中央
this.setResizable(false);//固定大小，用户不能调整大小
show.setPreferredSize(new Dimension(300, 100));
p1.add(show);
p2.setLayout(new GridLayout(5, 4, 2, 3));
//添加数字按键
for (int i = 0; i< text2.length; i++) {
munButton[i] = new JButton(text2[i] + " ");
p2.add(munButton[i]);
}
for (int i = 0; i< munButton.length; i++)
munButton[i].addActionListener(this);
this.setVisible(true);//窗体可视化
this.addWindowListener(new WindowAdapter() {//监听事件，当按下关闭按钮时，结束程序
@Override
public void windowClosing(WindowEvent e) {
System.exit(0);
}
});
}接着我们就开始进入到这个项目的最重要的部分了。
设置按钮监听事件，通过获取按钮的信息来进行判断运算。
在我们进行加减乘除计算的时候会出现一个特殊情况，除数为0，所以我们要预防出现异常影响程序的运行，我们就要进行异常的捕获处理，这里我是自定义了一个异常类munber_Exception，然后我们利用try｛｝catch｛｝语句来进行异常捕获和处理。
public double division(double x,double y)throws munber_Exception{
if(y==0){
throw new munber_Exception("除数不能为0！");
}
else{
return x/y;
}
}
@Override
public void actionPerformed(ActionEvent e) {
try { String act=e.getActionCommand();//这个方法返回的是事件源组件的“命令” ， 这个“命令” 实际上就是事件源组件上的“Label（标签）字符串”，即如果我按了“9”这个按钮他就会返回一个“9的值”
char a=act.charAt(0);//取act这个字符串的首字符
if (a=='0' ||a=='1' || a=='2' ||a=='3'||a=='4'||a=='5'||a=='6'||a=='7'||a=='8'||a=='9'||a=='.') {
if(oper=='~'){//当oper=='~'时，则操作符为空
strA.append(a);
show.setText(String.valueOf(strA));
}else {
strB.append(a);
show.setText(String.valueOf(strA)+oper+String.valueOf(strB));
}
}
else if(a=='+'||a=='-'||a=='/'||a=='*'||a=='%'){
oper=a;
show.setText(String.valueOf(strA)+oper);
}
else if(a=='='){
A = Double.parseDouble(String.valueOf(strA));
B = Double.parseDouble(String.valueOf(strB));
double j;
int len1=strA.length();
int len2=strB.length();
if (oper == '+') {
j = A + B;
show.setText(Double.toString(j));
strA.delete(0,len1);
strB.delete(0,len2);
strA.append(j);
} else if (oper == '-') {
j = A - B;
show.setText(Double.toString(j));
strA.delete(0,len1);
strB.delete(0,len2);
strA.append(j);
} else if (oper == '*') {
j = A * B;
show.setText(Double.toString(j));
strA.delete(0,len1);
strB.delete(0,len2);
strA.append(j);
} else if (oper == '/') {
try{j= division(A, B);}catch(munber_Exception u){
show.setText(u.shows());
}
}
else if (oper == '%') {
j = A % B;
show.setText(Double.toString(j));
strA.delete(0,len1);
strB.delete(0,len2);
strA.append(j);
}
} else if (a=='C') {//清除
show.setText(" ");
oper='~';
int len1=strA.length();
int len2=strB.length();
strA.delete(0,len1);
strB.delete(0,len2);
} else if (a=='D'){//删除
if(oper!='~'){
if(strB.length()>0){
strB.delete(strB.length()-1,strB.length());
show.setText(String.valueOf(strA)+oper+String.valueOf(strB));
}
else
show.setText("0");
}if(oper=='~'){
if(strA.length()>0){
strA.delete(strA.length()-1,strA.length());
show.setText(String.valueOf(strA));
}
}
} }catch(ArithmeticException m){
System.out.println("除数不能为0");
}
}class munber_Exception extends Exception{ //异常处理
String e;
public munber_Exception(){
}
public munber_Exception(String message){
this.e=message;
}
public String shows(){
return e;
}
}
class cal extends JFrame implements ActionListener {
private JPanel p1, p2;
private JTextArea show;
private String box ;
JMenuBar menubar;
JMenu menu1, menu2, menu3;
StringBuffer strA;
StringBuffer strB;
char oper ='~';
double A;
double B;
private String[] text2 = {"C", "CE","%", "/",
"7", "8", "9", "*",
"4", "5", "6", "-",
"1", "2", "3", "+",
"DEL","0", ".", "="};//计算器按钮面板
private JButton[] munButton = new JButton[text2.length];
public cal() {
p1 = new JPanel();
p2 = new JPanel();
show = new JTextArea();
p1.setSize(600, 100);
menubar = new JMenuBar();
menu1 = new JMenu("查看(V)");
menu2 = new JMenu("编辑(E)");
menu3 = new JMenu("帮助(H)");
strB=new StringBuffer();
strA=new StringBuffer();
}
public void init() {//初始化
this.setTitle("计算器");
this.setBounds(200, 200, 320, 300);
this.setLayout(new BorderLayout());
this.add(p1, BorderLayout.CENTER);
this.add(p2, BorderLayout.SOUTH);
menubar.add(menu1);
menubar.add(menu2);
menubar.add(menu3);
this.setJMenuBar(menubar);
this.setLocationRelativeTo(null);
this.setResizable(false);
show.setPreferredSize(new Dimension(300, 100));
p1.add(show);
p2.setLayout(new GridLayout(5, 4, 2, 3));
//添加数字按键
for (int i = 0; i< text2.length; i++) {
munButton[i] = new JButton(text2[i] + " ");
p2.add(munButton[i]);
}
for (int i = 0; i< munButton.length; i++)
munButton[i].addActionListener(this);
this.setVisible(true);
this.addWindowListener(new WindowAdapter() {
@Override
public void windowClosing(WindowEvent e) {
System.exit(0);
}
});
}
public double division(double x,double y)throws munber_Exception{
if(y==0){
throw new munber_Exception("除数不能为0！");
}
else{
return x/y;
}
}
@Override
public void actionPerformed(ActionEvent e) {
try { String act=e.getActionCommand();
char a=act.charAt(0);
if (a=='0' ||a=='1' || a=='2' ||a=='3'||a=='4'||a=='5'||a=='6'||a=='7'||a=='8'||a=='9'||a=='.') {
if(oper=='~'){
strA.append(a);
show.setText(String.valueOf(strA));
}else {
strB.append(a);
show.setText(String.valueOf(strA)+oper+String.valueOf(strB));
}
}
else if(a=='+'||a=='-'||a=='/'||a=='*'||a=='%'){
oper=a;
show.setText(String.valueOf(strA)+oper);
}
else if(a=='='){
A = Double.parseDouble(String.valueOf(strA));
B = Double.parseDouble(String.valueOf(strB));
double j;
int len1=strA.length();
int len2=strB.length();
if (oper == '+') {
j = A + B;
show.setText(Double.toString(j));
strA.delete(0,len1);
strB.delete(0,len2);
strA.append(j);
} else if (oper == '-') {
j = A - B;
show.setText(Double.toString(j));
strA.delete(0,len1);
strB.delete(0,len2);
strA.append(j);
} else if (oper == '*') {
j = A * B;
show.setText(Double.toString(j));
strA.delete(0,len1);
strB.delete(0,len2);
strA.append(j);
} else if (oper == '/') {
try{j= division(A, B);}catch(munber_Exception u){
show.setText(u.shows());
}
}
else if (oper == '%') {
j = A % B;
show.setText(Double.toString(j));
strA.delete(0,len1);
strB.delete(0,len2);
strA.append(j);
}
} else if (a=='C') {
show.setText(" ");
oper='~';
int len1=strA.length();
int len2=strB.length();
strA.delete(0,len1);
strB.delete(0,len2);
} else if (a=='D'){
if(oper!='~'){
if(strB.length()>0){
strB.delete(strB.length()-1,strB.length());
show.setText(String.valueOf(strA)+oper+String.valueOf(strB));
}
else
show.setText("0");
}if(oper=='~'){
if(strA.length()>0){
strA.delete(strA.length()-1,strA.length());
show.setText(String.valueOf(strA));
}
}
} }catch(ArithmeticException m){
System.out.println("除数不能为0");
}
}
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