这是我的完整代码---＆gt;＆gt;＆gt;＆gt;
package calculator;
import java.awt.Font;
import java.awt.GridLayout;
import javax.script.ScriptEngine;
import javax.script.ScriptEngineManager;
import javax.script.ScriptException;
import javax.swing.JPanel;
import javax.swing.JTextField;
public class CalField extends JPanel {
private JTextField field;
private String track = null;
private String s = "";
private int i = 0;
public CalField() {
setLayout(new GridLayout(1, 1, 5, 5));
field = new JTextField(20);
field.setFont(new Font("SansSerif", Font.PLAIN, 20));
field.setEditable(true);
add(field);
s = new String[50];
}
public JTextField getField() {
return field;
}
public void appendField(String text) {
if (field.getText().length() < 16) {
if (text == "+" || text == "-" || text == "*" || text == "/"
|| text == "(" || text == ")") {
track = null; // track for keep track of operator
if (track == null) {
track = text;
s = "";
}
field.setText(field.getText() + text);
} else if (field.getText().contains(".")) { // if JTextField's
// string
if (track != null) { // contains a "." then
if (text != ".") { // check
field.setText(field.getText() + text); // here
s.concat(text); //here is also problem
} else if (text == ".") {
if (!s.contains(".")) //here is also problem
field.setText(field.getText() + text);
else
field.setText(field.getText() + "");
}
}
else {
if (text == ".")
field.setText(field.getText() + "");
else
field.setText(field.getText() + text);
}
} else
field.setText(field.getText() + text); // if not contains "."
}
System.out.print(text);
}
public void calculate() {
Object result = "";
ScriptEngineManager manager = new ScriptEngineManager();
ScriptEngine engine = manager.getEngineByName("js");
try {
result = engine.eval(field.getText());
} catch (ScriptException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
String res = "";
res = String.valueOf(result);
field.setText(res);
}
public void setTrack(String track) {
this.track = track;
}
}
package calculator;
import java.awt.Font;
import java.awt.GridLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.Icon;
import javax.swing.ImageIcon;
import javax.swing.JButton;
import javax.swing.JPanel;
public class CalButton extends JPanel {
private JButton[] buttons;
private static final String[] buttonNames = { "7", "8", "9", "/", "4", "5", "6",
"*", "1", "2", "3", "-", "0", ".", "=", "+" };
private CalField calField;
public CalButton(CalField calField) {
buttons = new JButton[buttonNames.length];
setLayout(new GridLayout(4, 4, 3, 3));
this.calField = calField;
ButtonListener handler = new ButtonListener();
for (int i = 0; i < buttonNames.length; i++) {
buttons[i] = new JButton(buttonNames[i]);
buttons[i].setFont(new Font("SansSerif", Font.BOLD, 20));
add(buttons[i]);
buttons[i].addActionListener(handler);
}
}
private class ButtonListener implements ActionListener {
@Override
public void actionPerformed(ActionEvent event) {
// TODO Auto-generated method stub
if (buttons[0].getActionCommand() == event.getActionCommand()) {
calField.appendField(event.getActionCommand());
// System.out.print(buttons[0].getActionCommand());
} else if (buttons[1].getActionCommand() == event
.getActionCommand()) {
calField.appendField(event.getActionCommand());
// System.out.print(buttons[1].getActionCommand());
} else if (buttons[2].getActionCommand() == event
.getActionCommand()) {
calField.appendField(event.getActionCommand());
// System.out.print(buttons[2].getActionCommand());
} else if (buttons[3].getActionCommand() == event
.getActionCommand()) {
calField.appendField(event.getActionCommand());
// System.out.print(buttons[3].getActionCommand());
} else if (buttons[4].getActionCommand() == event
.getActionCommand()) {
calField.appendField(event.getActionCommand());
// System.out.print(buttons[4].getActionCommand());
} else if (buttons[5].getActionCommand() == event
.getActionCommand()) {
calField.appendField(event.getActionCommand());
// System.out.print(buttons[5].getActionCommand());
} else if (buttons[6].getActionCommand() == event
.getActionCommand()) {
calField.appendField(event.getActionCommand());
// System.out.print(buttons[6].getActionCommand());
} else if (buttons[7].getActionCommand() == event
.getActionCommand()) {
calField.appendField(event.getActionCommand());
// System.out.print(buttons[7].getActionCommand());
} else if (buttons[8].getActionCommand() == event
.getActionCommand()) {
calField.appendField(event.getActionCommand());
// System.out.print(buttons[8].getActionCommand());
} else if (buttons[9].getActionCommand() == event
.getActionCommand()) {
calField.appendField(event.getActionCommand());
// System.out.print(buttons[9].getActionCommand());
} else if (buttons[10].getActionCommand() == event
.getActionCommand()) {
calField.appendField(event.getActionCommand());
// System.out.print(buttons[10].getActionCommand());
} else if (buttons[11].getActionCommand() == event
.getActionCommand()) {
calField.appendField(event.getActionCommand());
// System.out.print(buttons[11].getActionCommand());
} else if (buttons[12].getActionCommand() == event
.getActionCommand()) {
calField.appendField(event.getActionCommand());
// System.out.print(buttons[12].getActionCommand());
} else if (buttons[13].getActionCommand() == event
.getActionCommand()) {
calField.appendField(event.getActionCommand());
// System.out.print(buttons[13].getActionCommand());
} else if (buttons[14].getActionCommand() == event
.getActionCommand()) {
// calField.getField().setText(String.valueOf(calField.eval(calField.getField().getText())));
calField.setTrack(null);
calField.calculate();
} else if (buttons[15].getActionCommand() == event
.getActionCommand()) {
calField.appendField(event.getActionCommand());
// System.out.print(buttons[15].getActionCommand());
}
}
}
}
package calculator;
import java.awt.BorderLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.Icon;
import javax.swing.ImageIcon;
import javax.swing.JButton;
import javax.swing.JPanel;
public class BackIcon extends JPanel {
private Icon backIcon = new ImageIcon(getClass().getResource(
"calculatorData/Back-24.png"));
private JButton button;
private CalField calField;
public BackIcon(CalField calField) {
setLayout(new BorderLayout());
button = new JButton(backIcon);
button.setSize(50, 50);
add(button, BorderLayout.EAST);
button.addActionListener(new BackButtonHandler());
this.calField = calField;
}
private class BackButtonHandler implements ActionListener {
@Override
public void actionPerformed(ActionEvent event) {
String str = "";
try {
str = calField.getField().getText();
} catch (Exception e) {
// TODO: handle exception
e.printStackTrace();
}
if (str != null) {
str = str.substring(0, str.length() - 1);
calField.getField().setText(str);
}
}
}
}
- ＆GT;主要类---＆gt;＆gt;＆gt;
package calculator;
import java.awt.BorderLayout;
import java.awt.Container;
import java.awt.GridLayout;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.SwingConstants;
public class Calculator {
public static void main(String[] args) {
JFrame application = new JFrame("Calculator");
application.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
application.setSize(250, 255);
application.setResizable(false);
CalField calField = new CalField();
BackIcon backIcon = new BackIcon(calField);
CalButton calButton = new CalButton(calField);
application.add(calField, BorderLayout.PAGE_START);
application.add(backIcon, BorderLayout.CENTER);
application.add(calButton, BorderLayout.PAGE_END);
application.setVisible(true);
}
}
在CalField课程的appendField()方法中，我遇到了问题。在这里，我想为每个小数（如44.5）数字只取一个点（。）。但在这个程序中，这只发生在我第一次输入十进制数字时。当我输入任何运算符（如+， - ，*，/）时，它可能需要多个点（如44 ....... 5）。请帮助我解决这个问题。