我完全清楚有更好的方法可以做到这一点，但只要它最终有效，我会完全满意它，每当我做4 + 4这样的操作时它是正确的，但如果我做4 + 4 *之类的事情2它将等于32
package calc;
import java.awt.FlowLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JTextField;
/**
*
* @author Ben
*/
public class GUI extends JFrame {
int response, operator;
double num1, num2, total = 0;
String operation, answer, num, testnum;
private JButton one, two, three, four, five, six, seven, eight,
nine, zero, multiply, divide, subtract, add, equals, clear;
private JTextField display, fakedisplay;
public GUI() {
super("Calculator");
setLayout(new FlowLayout());
fakedisplay = new JTextField(10);
display = new JTextField(10);;
add(display);
one = new JButton("1");
add(one);
two = new JButton("2");
add(two);
three = new JButton("3");
add(three);
four = new JButton("4");
add(four);
five = new JButton("5");
add(five);
six = new JButton("6");
add(six);
seven = new JButton("7");
add(seven);
eight = new JButton("8");
add(eight);
nine = new JButton("9");
add(nine);
zero = new JButton("0");
add(zero);
multiply = new JButton("*");
add(multiply);
divide = new JButton("/");
add(divide);
subtract = new JButton("-");
add(subtract);
add = new JButton("+");
add(add);
equals = new JButton("=");
add(equals);
clear = new JButton("Clear");
add(clear);
handler handle = new handler();
one.addActionListener(handle);
two.addActionListener(handle);
three.addActionListener(handle);
four.addActionListener(handle);
five.addActionListener(handle);
six.addActionListener(handle);
seven.addActionListener(handle);
eight.addActionListener(handle);
nine.addActionListener(handle);
zero.addActionListener(handle);
multiply.addActionListener(handle);
divide.addActionListener(handle);
subtract.addActionListener(handle);
add.addActionListener(handle);
equals.addActionListener(handle);
clear.addActionListener(handle);
}
private class handler implements ActionListener {
@
Override
public void actionPerformed(ActionEvent e) {
if(e.getSource() == one) {
response = 1;
display.setText(display.getText() + 1);
fakedisplay.setText(fakedisplay.getText() + 1);
} else if(e.getSource() == two) {
response = 2;
display.setText(display.getText() + 2);
fakedisplay.setText(fakedisplay.getText() + 2);
} else if(e.getSource() == three) {
response = 3;
display.setText(display.getText() + 3);
fakedisplay.setText(fakedisplay.getText() + 3);
} else if(e.getSource() == four) {
response = 4;
display.setText(display.getText() + 4);
fakedisplay.setText(fakedisplay.getText() + 4);
} else if(e.getSource() == five) {
response = 5;
display.setText(display.getText() + 5);
fakedisplay.setText(fakedisplay.getText() + 5);
} else if(e.getSource() == six) {
response = 6;
display.setText(display.getText() + 6);
fakedisplay.setText(fakedisplay.getText() + 6);
} else if(e.getSource() == seven) {
response = 7;
display.setText(display.getText() + 7);
fakedisplay.setText(fakedisplay.getText() + 7);
} else if(e.getSource() == eight) {
response = 8;
display.setText(display.getText() + 8);
fakedisplay.setText(fakedisplay.getText() + 8);
} else if(e.getSource() == nine) {
response = 9;
display.setText(display.getText() + 9);
fakedisplay.setText(fakedisplay.getText() + 9);
} else if(e.getSource() == zero) {
response = 0;
display.setText(display.getText() + 0);
fakedisplay.setText(fakedisplay.getText() + 0);
} else if(e.getSource() == multiply) {
if(operator == 0 && num1 == 0) {
num1 = Double.parseDouble(display.getText());
operator = 3;
fakedisplay.setText("");
} else if(operator != 0) {
operator = 3;
num2 = Double.parseDouble(fakedisplay.getText());
fakedisplay.setText("");
if(operator == 1) {
total = num1 + num2;
display.setText(display.getText() + operation + total);
num1 = total;
}
if(operator == 2) {
total = num1 - num2;
display.setText(display.getText() + operation + total);
num1 = total;
}
if(operator == 3) {
total = num1 * num2;
display.setText(display.getText() + operation + total);
num1 = total;
}
if(operator == 4) {
total = num1 / num2 + num1 % num2;
display.setText(display.getText() + operation + total);
num1 = total;
}
num2 = 0;
total = 0;
fakedisplay.setText("");
operator = 0;
}
operation = "*";
display.setText(display.getText() + operation);
} else if(e.getSource() == divide) {
if(operator == 0 && num1 == 0) {
num1 = Double.parseDouble(display.getText());
operator = 4;
fakedisplay.setText("");
} else if(total == 0) {
operator = 3;
} else if(operator != 0) {
operator = 4;
num2 = Double.parseDouble(fakedisplay.getText());
fakedisplay.setText("");
if(operator == 1) {
total = num1 + num2;
display.setText(display.getText() + operation + total);
num1 = total;
}
if(operator == 2) {
total = num1 - num2;
display.setText(display.getText() + operation + total);
num1 = total;
}
if(operator == 3) {
total = num1 * num2;
display.setText(display.getText() + operation + total);
num1 = total;
}
if(operator == 4) {
total = num1 / num2 + num1 % num2;
display.setText(display.getText() + operation + total);
num1 = total;
}
num2 = 0;
total = 0;
fakedisplay.setText("");
operator = 0;
}
operation = "/";
display.setText(display.getText() + operation);
} else if(e.getSource() == add) {
if(operator == 0 && num1 == 0) {
num1 = Double.parseDouble(display.getText());
operator = 1;
fakedisplay.setText("");
} else if(operator != 0) {
operator = 1;
num2 = Double.parseDouble(fakedisplay.getText());
fakedisplay.setText("");
if(operator == 1) {
total = num1 + num2;
display.setText(display.getText() + operation + total);
num1 = total;
}
if(operator == 2) {
total = num1 - num2;
display.setText(display.getText() + operation + total);
num1 = total;
}
if(operator == 3) {
total = num1 * num2;
display.setText(display.getText() + operation + total);
num1 = total;
}
if(operator == 4) {
total = num1 / num2 + num1 % num2;
display.setText(display.getText() + operation + total);
num1 = total;
}
num2 = 0;
total = 0;
fakedisplay.setText("");
operator = 0;
}
operation = "+";
display.setText(display.getText() + operation);
} else if(e.getSource() == subtract) {
if(operator == 0 && num1 == 0) {
num1 = Double.parseDouble(display.getText());
operator = 2;
fakedisplay.setText("");
} else if(operator != 0) {
operator = 2;
num2 = Double.parseDouble(fakedisplay.getText());
fakedisplay.setText("");
if(operator == 1) {
total = num1 + num2;
display.setText(display.getText() + operation + total);
num1 = total;
}
if(operator == 2) {
total = num1 - num2;
display.setText(display.getText() + operation + total);
num1 = total;
}
if(operator == 3) {
total = num1 * num2;
display.setText(display.getText() + operation + total);
num1 = total;
}
if(operator == 4) {
total = num1 / num2 + num1 % num2;
display.setText(display.getText() + operation + total);
num1 = total;
}
num2 = 0;
total = 0;
fakedisplay.setText("");
operator = 0;
}
operation = "-";
display.setText(display.getText() + operation);
} else if(e.getSource() == equals) {
if(operator == 0) {
display.setText("Error");
} else if(operator != 0) {
num2 = Double.parseDouble(fakedisplay.getText());
fakedisplay.setText("");
if(operator == 1) {
total = num1 + num2;
display.setText(display.getText() + "=" + total);
}
if(operator == 2) {
total = num1 - num2;
display.setText(display.getText() + "=" + total);
}
if(operator == 3) {
total = num1 * num2;
display.setText(display.getText() + "=" + total);
}
if(operator == 4) {
total = num1 / num2 + num1 % num2;
display.setText(display.getText() + "=" + total);
}
}
operation = "=";
} else if(e.getSource() == clear) {
display.setText("");
fakedisplay.setText("");
operator = 0;
total = 0;
num1 = 0;
num2 = 0;
}
System.out.println("num1: " + num1 + " num2: " + num2 + "\ndisplay: " + display.getText() + " fakedisplay: " + fakedisplay.getText() + "\nresponse: " + response + "\noperator: " + operator + "\ntotal: " + total + "\n==========================");
}
}
}
答案 0 :(得分：0)
我只能引导您访问一些在线信息，您需要进行解析。将最终命令字符串的每个标记（+ - * /）放在一个列表中（可能是二叉树工作）并对该列表进行排序，以告诉计算器除法和乘法在平均时间加法中具有最高优先级，并且减法具有较低的优先级。
您对命令数组进行排序，使得leftside优先于右侧。然后它从左到右开始计算，同时首先选择div / mult。
http://www.slideshare.net/dabeaz/writing-parsers-and-compilers-with-ply
http://parsingintro.sourceforge.net/
http://www.dreamincode.net/forums/topic/268945-an-introduction-to-compiler-design-part-ii-parsing/
https://en.wikipedia.org/wiki/Parsing
http://arantxa.ii.uam.es/~modonnel/Compilers/03_1_Parsing_Intro.pdf
如果你太累了，你可以使用script engine of java来自用户“Andrew Thompson”的建议。
答案 1 :(得分：0)
我认为你可能会采用不同的方式。您正在设计复杂的解决方案 一个非常简单的问题。
1. First of all Use a single JTextField for the user to enter the entire expression.
i.e. [ 4+4*2].
2. Second Provide a Submit Buttons( jbutton ) along with text field.
Now when the User is finished with entering expression he will click the submit button.
i.e [4+4*2] [Click to Submit]
不，你为这个按钮编写处理程序。 在处理程序中只读取整个表达式 文本域 并按照 反向波兰表示法以评估您的结果。 它非常简单的基于堆栈的算法。通常在数据结构类中讲授。 请参阅此文http://en.wikipedia.org/wiki/Reverse_Polish_notation