calculator.java

用java编程实现一个简单的计算器,实现基本的加减乘除运算。

answerd = Double.parseDouble(textAnswer.getText()); 
} 
textAnswer.setText(""); 
prekey = key = 2; 
} 
//'/'操作 
if (temp == buttonDiv) { 
switch (prekey) { 
case 0: 
answerd += Double.parseDouble(textAnswer.getText()); 
break; 
case 1: 
answerd -= Double.parseDouble(textAnswer.getText()); 
break; 
case 2: 
answerd *= Double.parseDouble(textAnswer.getText()); 
break; 
case 3: 
if (Double.parseDouble(textAnswer.getText()) == 0) { 
textAnswer.setText("除数不能为零"); 
clickable = false; 
} 
else 
answerd /= Double.parseDouble(textAnswer.getText()); 
break; 
default: 
answerd = Double.parseDouble(textAnswer.getText()); 
} 
textAnswer.setText(""); 
prekey = key = 3; 
} 
} 
//'='操作 
if (temp == buttonEqual && clickable == true) { 
//如果连续按'=',则进行连续运算 
if (prekey == 5) { 
if (key == 0) { 
answerd += vard; 
textAnswer.setText(df.format(answerd)); 
} 
if (key == 1) { 
answerd -= vard; 
textAnswer.setText(df.format(answerd)); 
} 
if (key == 2) { 
answerd *= vard; 
textAnswer.setText(df.format(answerd)); 
} 
if (key == 3) { 
if (Double.parseDouble(textAnswer.getText()) == 0) { 
textAnswer.setText("除数不能为零"); 
clickable = false; 
} 
else { 
answerd /= vard; 
textAnswer.setText(df.format(answerd)); 
} 
} 
} 
else { 
vard = Double.parseDouble(textAnswer.getText()); 
if (key == 0) { 
prekey = -1; 
answerd += Double.parseDouble(textAnswer.getText()); 
textAnswer.setText(df.format(answerd)); 
} 
if (key == 1) { 
prekey = -1; 
answerd -= Double.parseDouble(textAnswer.getText()); 
textAnswer.setText(df.format(answerd)); 
} 
if (key == 2) { 
prekey = -1; 
answerd *= Double.parseDouble(textAnswer.getText()); 
textAnswer.setText(df.format(answerd)); 
} 
if (key == 3) { 
prekey = -1; 
if (Double.parseDouble(textAnswer.getText()) == 0) { 
textAnswer.setText("除数不能为零"); 
clickable = false; 
} 
else { 
answerd /= Double.parseDouble(textAnswer.getText()); 
textAnswer.setText(df.format(answerd)); 
} 
} 
} 
prekey = 5; 
} 
//'%'操作，对第二个操作数除以100 
if (temp == buttonMod && clickable == true) { 
if (answerd == 0) { 
String s = textAnswer.getText(); 
textAnswer.setText(s); 
} 
else { 
boolean isDot = false; 
for (int i = 0; i < textAnswer.getText().length(); i++) 
if ('.' == textAnswer.getText().charAt(i)) { 
isDot = true; 
break; 
} 
//如果是double数，除100 
if (isDot == true) { 
double dtemp = Double.parseDouble(textAnswer.getText()); 
dtemp = dtemp / 100.0; 
textAnswer.setText(Double.toString(dtemp)); 
} 
else { 
//如果是int数但能被100整除，则去掉末尾两个零 
if (Integer.parseInt(textAnswer.getText()) % 100 == 0) { 
int itemp = Integer.parseInt(textAnswer.getText()); 
itemp /= 100; 
textAnswer.setText(Integer.toString(itemp)); 
} 
//如果是int数，但不能被100整除，则按double数处理 
else { 
double dtemp = Double.parseDouble(textAnswer.getText()); 
dtemp = dtemp / 100.0; 
textAnswer.setText(Double.toString(dtemp)); 
} 
} 
} 
} 
//开根号运算 
if (temp == buttonSqrt && clickable == true) { 
String s = textAnswer.getText(); 
if (s.charAt(0) == '-') { 
textAnswer.setText("负数不能开根号"); 
clickable = false; 
} 
else 
textAnswer.setText(Double.toString(java.lang.Math.sqrt(Double. 
parseDouble(textAnswer.getText())))); 
} 
//倒数运算 
if (temp == buttonDao && clickable == true) { 
if (textAnswer.getText().charAt(0) == '0' && 
textAnswer.getText().length() == 1) { 
textAnswer.setText("零不能求倒数"); 
clickable = false; 
} 
else { 
boolean isDec = true; 
int i, j, k; 
String s = Double.toString(1 / Double.parseDouble(textAnswer.getText())); 
for (i = 0; i < s.length(); i++) 
if (s.charAt(i) == '.') 
break; 
for (j = i + 1; j < s.length(); j++) 
if (s.charAt(j) != '0') { 
isDec = false; 
break; 
} 
if (isDec == true) { 
String stemp = ""; 
for (k = 0; k < i; k++) 
stemp += s.charAt(k); 
textAnswer.setText(stemp); 
} 
else 
textAnswer.setText(s); 
} 
} 
//按下'+/-'按钮时处理 
if (temp == buttonAddAndSub && clickable == true) { 
boolean isNumber = true; 
String s = textAnswer.getText(); 
for (int i = 0; i < s.length(); i++) 
if (! (s.charAt(i) >= '0' && s.charAt(i) <= '9' || s.charAt(i) == '.' || 
s.charAt(i) == '-')) { 
isNumber = false; 
break; 
} 
if (isNumber == true) { 
//如果当前字符串首字母有'-'号,代表现在是个负数,再按下时,则将首符号去掉 
if (s.charAt(0) == '-') { 
textAnswer.setText(""); 
for (int i = 1; i < s.length(); i++) { 
char a = s.charAt(i); 
textAnswer.setText(textAnswer.getText() + a); 
} 
} 
//如果当前字符串第一个字符不是符号，则添加一个符号在首字母处 
else 
textAnswer.setText('-' + s); 
} 
} 


//计算器有关内存操作 
//'MC'的操作，将内存清0 
if (temp == buttonMC && clickable == true) { 
memoryd = memoryi = 0; 
textMemory.setText(""); 
} 
//'MS'的操作，将当前文本框内容保存入内存，显示'M' 
if (temp == buttonMS && clickable == true) { 
boolean isDot = false; 
textMemory.setText(" M"); 
for (int i = 0; i < textAnswer.getText().length(); i++) 
if ('.' == textAnswer.getText().charAt(i)) { 
isDot = true; 
break; 
} 
//如果是double,则存入memoryd(double存储器) 
if (isDot == true) { 
memoryd = Double.parseDouble(textAnswer.getText()); 
memoryi = 0; //保证存储器中存放最新的值 
} 
//如果是int,则存入memoryi(int存储器) 
else { 
memoryi = Integer.parseInt(textAnswer.getText()); 
memoryd = 0; //保证存储器中存放最新的值 
} 
} 
//'MR'的操作，将存储器中的信息输出 
if (temp == buttonMR && clickable == true) { 
if (memoryd != 0) 
textAnswer.setText(Double.toString(memoryd)); 
if (memoryi != 0) 
textAnswer.setText(Integer.toString(memoryi)); 
} 
//'M+'的功能，将当前文本框里的数据和存储器中数据相加后，再存入存储器 
if (temp == buttonMAdd && clickable == true) { 
boolean isDot = false; 
for (int i = 0; i < textAnswer.getText().length(); i++) 
if ('.' == textAnswer.getText().charAt(i)) { 
isDot = true; 
break; 
} 
if (memoryi != 0) { //存储中是一个int型数 
if (isDot == false) //被加数是一个int型数 
memoryi += Integer.parseInt(textAnswer.getText()); 
else { //被加数是一个double型数，则将int存储器中数传入double存储器与当前数相加，int存储器清零 
memoryd = memoryi + Double.parseDouble(textAnswer.getText()); 
memoryi = 0; 
} 
} 
else 
memoryd += Double.parseDouble(textAnswer.getText()); 
} 
//按下'Backspace'键，利用循环将当前字符串中的最后一个字母删除 
if (temp == buttonBk && clickable == true) { 
String s = textAnswer.getText(); 
textAnswer.setText(""); 
for (int i = 0; i < s.length() - 1; i++) { 
char a = s.charAt(i); 
textAnswer.setText(textAnswer.getText() + a); 
} 
} 
//按下'CE'按钮，将当前文本框内数据清除 
if (temp == buttonCe) { 
textAnswer.setText(""); 
clickable = true; 
} 
//按下'C'按钮，文本框内数据清除，同时var,answer清0 
if (temp == buttonC) { 
vard = answerd = 0; 
textAnswer.setText(""); 
clickable = true; 
} 
//按下'复制'菜单栏 
if (temp == copyItem) { 
copy = textAnswer.getText(); 
} 
//按下'粘贴'菜单栏 
if (temp == pasteItem) { 
textAnswer.setText(copy); 
} 
if (temp == sItem) { 
JOptionPane.showMessageDialog(panel, "当前是标准型计算器，\n科学型计算器有待更新。"); 
} 
//按下'帮助主题'菜单栏 
if (temp == topHelp) { 
JOptionPane.showMessageDialog(panel, scrollHelp); 
} 
//按下'数字分组'菜单栏 
if (temp == numberGroup) { 
if (numberGroup.getText().compareTo(" 数字分组(I)") == 0) 
numberGroup.setText("√数字分组(I)"); 
else 
numberGroup.setText(" 数字分组(I)"); 
} 
//按下'关于'菜单栏 
if (temp == aboutCal) { 
JOptionPane.showMessageDialog(panel, "计算器1.00版\n开发者：楼竞"); 
} 
} 
//输入中如果有操作非法，比如按下两次'+'，捕获异常 
catch (Exception e) { 
textAnswer.setText("操作非法"); 
clickable = false; 
} 
} 
//主函数 
public static void main(String args[]) { 
new Calculator(); 
} 
}