共有4个类：Main，GUI，Logic和Calculator。我难以使计算器类正确，第一个操作/计算给了我错误的答案，但下一个是正确的。我尝试为第一个和第二个数字创建另一个变量（fnum和snum），但它不起作用。我需要修改Logic类吗？
主要课程
class Main
{
public static void main( String args[] )
{
GUI gui = new GUI();
gui.display();
}
}
GUI类
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
class GUI
{
private static final int H = 400; // Height of window pixels
private static final int W = 500; // Width of window pixels
private JLabel theMes = new JLabel(); // Message area
private JTextArea theOutput1 = new JTextArea(); // Input number area
private JTextArea theOutput2 = new JTextArea(); // Result area
private JScrollPane theSP = new JScrollPane();
private ButtonPress onButtonPress = new ButtonPress();
public void display()
{
JFrame rpc = new JFrame(); // Window
Container cp = rpc.getContentPane(); // Content Pane
Container rootWindow = (Container) rpc; // Root Window
cp.setLayout(null); // No layout manager
rootWindow.setSize( W, H ); // Size of Window
String labels[] = {
"7", "8", "9", "", "CR", "+",
"4", "5", "6", "", "=", "-",
"1", "2", "3", "", "", "*",
"C", "0", "", "", "", "/" };
final int LABELS = labels.length; // # Button Labels
final int GAP = 15; // Horizontal Gap
final int HLAB = 20; // Label
final int SHLAB = GAP;
final int EHLAB = SHLAB+HLAB;
final int HTA1 = 30; // Output area 1
final int SHTA1 = EHLAB + GAP;
final int EHTA1 = SHTA1 + HTA1;
final int HTA2 = 100; // Output area 2
final int SHTA2 = EHTA1 + GAP;
final int EHTA2 = SHTA2 + HTA2;
final int HBUT = 170; // Buttons
final int SHBUT = EHTA2 + GAP;
final int BNR = 4, BNC = 6; // number rows cols of buttons
final int BW = W/BNC, BH = HBUT/BNR; // Size of landscape for button
final int SBH = SHBUT, SBW = 7; // Start position for buttons
JButton buttons[] = new JButton[LABELS];
Font font = new Font("Serif",Font.BOLD,20); // Button font
for ( int i=0; i<LABELS; i++ )
{
if ( labels[i].length() >= 1 )
{
buttons[i] = new JButton( labels[i] );
final int col = i%BNC * BW, row = i/BNC * BH;
buttons[i].setBounds( SBW+col, SBH+row, BW-20, BH-10 );
buttons[i].addActionListener( onButtonPress );
buttons[i].setFont( font );
cp.add( buttons[i] );
}
}
font = new Font("Serif",Font.BOLD,14); // Font is
theMes.setBounds( 10, SHLAB, W-25, HLAB ); // Message area
theMes.setText( "" ); // Blank
theOutput1.setFont( font ); // Uses font
cp.add( theMes ); // Add to canvas
theOutput1.setBounds( 10, SHTA1, W-25, HTA1 ); // Input Area
theOutput1.setText(""); // Blank
theOutput1.setFont( font ); // Uses font
cp.add( theOutput1 ); // Add to canvas
font = new Font("Serif",Font.BOLD,14); // Font is
theSP.setBounds( 10, SHTA2, W-25, HTA2 ); // Scrolling pane
theOutput2.setText( "" ); // Blank
theOutput2.setFont( font ); // Uses font
cp.add( theSP ); // Add to canvas
theSP.getViewport().add( theOutput2 ); // In TextArea
rootWindow.setVisible( true ); // Make visible
theMes.setText( "Calculator" ); // Opening message
}
private Calculator calc = new Calculator();
private Logic logic = new Logic( calc );
class ButtonPress implements ActionListener // Listener
{
public void actionPerformed( ActionEvent ae ) // Interaction
{
String label = ae.getActionCommand(); // Button label
String info = logic.process( label);
theOutput2.setText( "" );
if ( info == null )
theOutput2.append( "" + logic.getResult() );
else
theOutput2.append( info );
theOutput1.setText( "" );
theOutput1.append( "Number entered: " + logic.getNumber() );
}
}
}
逻辑课
class Logic
{
private enum State { FIRST_NUMBER, SUBSEQUENT_NUMBER };
private State state = State.FIRST_NUMBER;
private long number = 0;
private char op = ' ';
private Calculator calc = null;
public Logic( Calculator calculator )
{
calc = calculator;
}
public String process( String button )
{
String info = null;
if ( button.length() == 1 )
{
char c = button.charAt(0);
if ( c >= '0' && c <= '9' ) // Digit
{
number = number * 10 + c-'0'; // Build number
} else {
switch ( c )
{
case 'C' : number = 0;
break;
case '=' :
case '+' : case '-' :
case '*' : case '/' :
switch ( state )
{
case FIRST_NUMBER:
calc.setValue( number );
state = State.SUBSEQUENT_NUMBER;
break;
case SUBSEQUENT_NUMBER:
if ( op != '=' )
calc.evaluate( op, number );
break;
}
op = c; number = 0;
break;
}
}
} else {
if ( button.equals( "CR" ) ) // Clear Result
{
calc.reset(); number = 0; state = State.FIRST_NUMBER;
}
}
return info;
}
public long getResult()
{
return calc.getValue();
}
public long getNumber()
{
return number;
}
}
计算器类
class Calculator
{
//Evaluate an arithmetic operation on the stored result
// E.g evaluate( '+',9) would add 9 to the stored result
// evaluate( '/',3) would divide the stored result
// by 3
// actions are '+'. '-', '*', '/'
//Note: if the operation is
// evaluate( '/',0 ) the result returned should be 0
long value;
public void evaluate( char action, long number )
{
if (action == '+'){
value += Float.valueOf(number).floatValue();
}
else if (action == '-'){
value -= Float.valueOf(number).floatValue();
}
else if (action == '*'){
value *= Float.valueOf(number).floatValue();
}
else if (action == '/'){
value /= Float.valueOf(number).floatValue();
}
}
//Return the stored result
public long getValue()
{
return value;
}
//Set the stored result to number
public void setValue( long number )
{
}
//Reset the stored number to 0
public void reset()
{
if ( value != 0) value = 0;
}
}
答案 0 :(得分：3)
问题是你实际上没有在setValue方法中设置值：
//Set the stored result to number
public void setValue( long number )
{
this.value = number;
}
那应该解决它。
答案 1 :(得分：2)
由于已经指出了答案，这里有一些关于代码的一般指示：
rpc.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);中添加GUI，否则您的计算器类将连续运行，甚至 后面的“退出”图标已关闭。Container rootWindow = (Container) rpc;毫无意义，因为rpc已被作为容器引用。HLAB，SHTA1，HTA2？）。始终以恰当和描述性的方式标记事物。long来存储和显示您的值，但是float来执行实际数学运算。这意味着程序会生成奇怪的结果 - 例如9 / 2 = 4。另外，与您的评论相反，9 / 0 = 9223372036854775807。我建议您生成初始数字（'输入数字'）作为字符的stacj，并使用BigDecimal执行所有数学运算。JPanel，每个都有适当的布局管理器。如有必要，可以使用IDE和插件来直观地设计此类系统。SwingUtilities.invokeLater();调度所有图形内容创建和操作，包括创建主窗口。pow函数）不需要修改代码，只需添加新行为（和按钮）。对于进一步和未来的批评，请在CodeReview上发布代码！
答案 2 :(得分：0)
package Calculator;
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
public class Carl extends JFrame {
JTextField text1 = new JTextField();
JLabel label1 = new JLabel(" ");
JButton button1 = new JButton("1");
JButton button2 = new JButton("2");
JButton button3 = new JButton("3");
JButton button4 = new JButton("4");
JButton button5 = new JButton("5");
JButton button6 = new JButton("6");
JButton button7 = new JButton("7");
JButton button8 = new JButton("8");
JButton button9 = new JButton("9");
JButton button10 = new JButton("0");
JButton button11 = new JButton("+");
JButton button12 = new JButton("-");
JButton button13 = new JButton("*");
JButton button14 = new JButton("/");
JButton button15 = new JButton("=");
JButton button16 = new JButton("C");
JLabel blank1 = new JLabel("");
JLabel blank2 = new JLabel("");
JLabel blank3 = new JLabel("");
JLabel blank4 = new JLabel("");
Font times = new Font("Times New Roman", Font.BOLD, 18);
int operation1;
int operation2;
int operation3;
int operation4;
String n1, n2;
JPanel p1 = new JPanel();
JPanel p2 = new JPanel();
public Carl() {
setResizable(true);
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
setTitle("Calculator");
setSize(600, 600);
button1.setForeground(Color.BLACK);
button2.setForeground(Color.BLACK);
button3.setForeground(Color.BLACK);
button4.setForeground(Color.BLACK);
button5.setForeground(Color.BLACK);
button6.setForeground(Color.BLACK);
button7.setForeground(Color.BLACK);
button8.setForeground(Color.BLACK);
button9.setForeground(Color.BLACK);
button10.setForeground(Color.BLACK);
button11.setForeground(Color.BLACK);
button12.setForeground(Color.BLACK);
button13.setForeground(Color.BLACK);
button14.setForeground(Color.BLACK);
button15.setForeground(Color.BLACK);
button16.setForeground(Color.BLACK);
button1.setBackground(Color.YELLOW);
button2.setBackground(Color.YELLOW);
button3.setBackground(Color.YELLOW);
button4.setBackground(Color.YELLOW);
button5.setBackground(Color.YELLOW);
button6.setBackground(Color.YELLOW);
button7.setBackground(Color.YELLOW);
button8.setBackground(Color.YELLOW);
button9.setBackground(Color.YELLOW);
button10.setBackground(Color.YELLOW);
button11.setBackground(Color.YELLOW);
button12.setBackground(Color.YELLOW);
button13.setBackground(Color.YELLOW);
button14.setBackground(Color.YELLOW);
button15.setBackground(Color.YELLOW);
button16.setBackground(Color.YELLOW);
button1.setToolTipText("one");
button2.setToolTipText("two");
button3.setToolTipText("three");
button4.setToolTipText("four");
button5.setToolTipText("five");
button6.setToolTipText("six");
button7.setToolTipText("seven");
button8.setToolTipText("eight");
button9.setToolTipText("nine");
button10.setToolTipText("zero");
button11.setToolTipText("addition");
button12.setToolTipText("subtraction");
button13.setToolTipText("multiplication");
button14.setToolTipText("division");
button15.setToolTipText("equal");
button16.setToolTipText("clear");
button1.setFont(times);
button2.setFont(times);
button3.setFont(times);
button4.setFont(times);
button5.setFont(times);
button6.setFont(times);
button7.setFont(times);
button8.setFont(times);
button9.setFont(times);
button10.setFont(times);
button11.setFont(times);
button12.setFont(times);
button13.setFont(times);
button14.setFont(times);
button15.setFont(times);
button16.setFont(times);
label1.setFont(times);
setLayout(new BorderLayout());
p1.setLayout(new GridLayout(6, 3, 2, 2));
p1.add(p2, BorderLayout.CENTER);
p1.add(label1);
p1.add(text1);
p1.add(blank3);
p1.add(button7);
p1.add(button8);
p1.add(button9);
p1.add(button11);
p1.add(button4);
p1.add(button5);
p1.add(button6);
p1.add(button12);
p1.add(button1);
p1.add(button2);
p1.add(button3);
p1.add(button13);
p1.add(button10);
p1.add(button16);
p1.add(button15);
p1.add(button14);
add(p1, BorderLayout.CENTER);
button1.addActionListener(new Listener1());
button2.addActionListener(new Listener2());
button3.addActionListener(new Listener3());
button4.addActionListener(new Listener4());
button5.addActionListener(new Listener5());
button6.addActionListener(new Listener6());
button7.addActionListener(new Listener7());
button8.addActionListener(new Listener8());
button9.addActionListener(new Listener9());
button10.addActionListener(new Listener0());
button11.addActionListener(new ListenerAdd());
button12.addActionListener(new ListenerSub());
button13.addActionListener(new ListenerMul());
button14.addActionListener(new ListenerDiv());
button15.addActionListener(new ListenerEqual());
button16.addActionListener(new ListenerClear());
setVisible(true);
}
private class Listener1 implements ActionListener {
public void actionPerformed(ActionEvent a) {
n1 = text1.getText();
text1.setText(n1 + "1");
}
}
private class Listener2 implements ActionListener {
public void actionPerformed(ActionEvent b) {
n1 = text1.getText();
text1.setText(n1 + "2");
}
}
private class Listener3 implements ActionListener {
public void actionPerformed(ActionEvent c) {
n1 = text1.getText();
text1.setText(n1 + "3");
}
}
private class Listener4 implements ActionListener {
public void actionPerformed(ActionEvent d) {
n1 = text1.getText();
text1.setText(n1 + "4");
}
}
private class Listener5 implements ActionListener {
public void actionPerformed(ActionEvent e) {
n1 = text1.getText();
text1.setText(n1 + "5");
}
}
private class Listener6 implements ActionListener {
public void actionPerformed(ActionEvent f) {
n1 = text1.getText();
text1.setText(n1 + "6");
}
}
private class Listener7 implements ActionListener {
public void actionPerformed(ActionEvent g) {
n1 = text1.getText();
text1.setText(n1 + "7");
}
}
private class Listener8 implements ActionListener {
public void actionPerformed(ActionEvent h) {
n1 = text1.getText();
text1.setText(n1 + "8");
}
}
private class Listener9 implements ActionListener {
public void actionPerformed(ActionEvent i) {
n1 = text1.getText();
text1.setText(n1 + "9");
}
}
private class Listener0 implements ActionListener {
public void actionPerformed(ActionEvent j) {
n1 = text1.getText();
text1.setText(n1 + "0");
}
}
private class ListenerAdd implements ActionListener {
public void actionPerformed(ActionEvent k) {
n2 = text1.getText();
operation1 = 1;
text1.setText("");
}
}
private class ListenerSub implements ActionListener {
public void actionPerformed(ActionEvent l) {
n2 = text1.getText();
operation2 = 2;
text1.setText("");
}
}
private class ListenerMul implements ActionListener {
public void actionPerformed(ActionEvent m) {
n2 = text1.getText();
operation3 = 3;
text1.setText("");
}
}
private class ListenerDiv implements ActionListener {
public void actionPerformed(ActionEvent n) {
n2 = text1.getText();
operation4 = 4;
text1.setText("");
}
}
private class ListenerEqual implements ActionListener {
public void actionPerformed(ActionEvent o) {
if (operation1 == 1) {
int a = Integer.parseInt(n2);
int b = Integer.parseInt(text1.getText());
int sum = (a + b);
String sum1 = Integer.toString(sum);
text1.setText(sum1);
} else {
text1.getText();
}
if (operation2 == 2) {
int a = Integer.parseInt(n2);
int b = Integer.parseInt(text1.getText());
int dif = (a - b);
String dif1 = Integer.toString(dif);
text1.setText(dif1);
} else {
text1.getText();
}
if (operation3 == 3) {
int a = Integer.parseInt(n2);
int b = Integer.parseInt(text1.getText());
int product = (a * b);
String product1 = Integer.toString(product);
text1.setText(product1);
} else {
text1.getText();
}
if (operation4 == 4) {
double a = Double.parseDouble(n2);
double b = Double.parseDouble(text1.getText());
double quo = (a / b);
String quo1 = Double.toString(quo);
text1.setText(quo1);
} else {
text1.getText();
}
}
}
private class ListenerClear implements ActionListener {
@Override
public void actionPerformed(ActionEvent p) {
text1.setText("");
}
}
public static void main(String[] args) {
Carl frame = new Carl();
}
}
使用此代码..