calculator1.java

用java实现的关于计算器的设计及功能实现

              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^o^科学型计算器有待更新^o^");
      }
      //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-JAVA课程设计\n制作者:梁辰");
      }
    }
    //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();
  }
}
/*
  GridBagLayout的使用：是java中最有弹性但也是最复杂的一种版面管理器。它只有一种构造函数，但必须配合
GridBagConstraints才能达到设置的效果。
GridBagLayout的类层次结构图：
java.lang.Object
--java.awt.GridBagLayout
构造函数：
GirdBagLayout()建立一个新的GridBagLayout管理器。
GridBagConstraints()建立一个新的GridBagConstraints对象。
GridBagConstraints(int gridx,int gridy,int gridwidth,int gridheight,double weightx,double weighty,
int anchor,int fill, Insets insets,int ipadx,int ipady)建立一个新的GridBagConstraints对象
，并指定其参数的值。
参数说明:
gridx,gridy:设置组件的位置，gridx设置为GridBagConstraints.RELATIVE代表此组件位于之前所加入组件的右边。
若将gridy设置为GridBagConstraints.RELATIVE代表此组件位于以前所加入组件的下面。建议定义出
gridx,gridy的位置，以便以后维护程序。表示放在几行几列，gridx=0,gridy=0时放在0行0列。

gridwidth,gridheight:用来设置组件所占的单位长度与高度，默认值皆为1。你可以使用GridBagConstraints.REMAINDER常
量，代表此组件为此行或此列的最后一个组件，而且会占据所有剩余的空间。

weightx,weighty:用来设置窗口变大时，各组件跟着变大的比例，当数字越大，表示组件能得到更多的空间，默认值皆为0。
anchor: 当组件空间大于组件本身时，要将组件置于何处，有CENTER(默认值)、NORTH、NORTHEAST、EAST、SOUTHEAST、
WEST、NORTHWEST可供选择。
insets:设置组件之间彼此的间距，它有四个参数，分别是上，左，下，右，默认为(0,0,0,0).
ipadx,ipady:设置组件内的间距，默认值为0。
我们以前提过，GridBagLayout里的各种设置都必须通过GridBagConstraints,因此当我们将GridBagConstraints的参数都设置 
*/