java语言综合设计实验报告(4)

}

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); }

// 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 MyCalculator(); }

}

四、运行结果：

五、重点代码分析

这一部分涉及到程序功能的算法问题

public void actionPerformed(ActionEvent event) { Object temp = event.getSource(); try {

// 如果按下数据按钮，将按下的按钮代表的数据插入的当前文本框字符串之后

for (int i = 0; i <= 9; i++)

if (temp == button[i] && clickable == true) { if(resultIndicate) {

textAnswer.setText(\); clickable = true;

textAnswer.setText(textAnswer.getText() + Integer.toString(i)); }

else {

textAnswer.setText(textAnswer.getText() + Integer.toString(i)); } }

// 按下′.′按钮时，判断当前文本框内字符串中含不含′.′，如果已含，则不允许再插入′.′

if (temp == buttonDot && clickable == true) { boolean isDot = false;

if (textAnswer.getText().length() == 0) { //isDot = true; isDot = false; dotFlag = true; }

for (int i = 0; i < textAnswer.getText().length(); i++) if ('.' == textAnswer.getText().charAt(i)) { isDot = true; break; }

if (isDot == false) { if (dotFlag)

textAnswer.setText('0' + \); else

textAnswer.setText(textAnswer.getText() + \); } }

if ((temp == buttonAdd || temp == buttonSub || temp == buttonMul ||

temp == buttonDiv) && clickable == true) {

// ′+′操作

if (temp == buttonAdd) { 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 = 0; }

// ′-′操作

if (temp == buttonSub) { 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 = 1; }

// ′*′操作

if (temp == buttonMul) { 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 = 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; } }