我用java实现计算器时,将键盘的退格键连接了按钮退格键,为什么我一按下键盘的退格键就会发出提示音,而按下退格按钮则不会,怎么解决
时间: 2024-01-27 15:03:04 浏览: 48
这是因为键盘的退格键和按钮的退格键的事件处理方式不同。键盘的退格键在处理事件时会触发系统提示音,而按钮的退格键则不会。要解决这个问题,你可以在按钮的事件处理方法中屏蔽掉系统提示音,可以使用如下代码:
```java
button.addActionListener(new ActionListener() {
@Override
public void actionPerformed(ActionEvent e) {
// 屏蔽系统提示音
e.consume();
// 处理退格事件
// ...
}
});
```
在事件处理方法中使用 `e.consume()` 可以屏蔽事件的后续处理,包括系统提示音。这样就可以避免在按下按钮退格键时发出系统提示音的问题。
相关问题
使用Qt实现使用键盘事件的计算器程序
以下是使用Qt实现使用键盘事件的计算器程序的示例代码:
mainwindow.h:
```c++
#ifndef MAINWINDOW_H
#define MAINWINDOW_H
#include <QMainWindow>
QT_BEGIN_NAMESPACE
namespace Ui { class MainWindow; }
QT_END_NAMESPACE
class MainWindow : public QMainWindow
{
Q_OBJECT
public:
MainWindow(QWidget *parent = nullptr);
~MainWindow();
private:
Ui::MainWindow *ui;
private slots:
void on_digitButton_clicked();
void on_operatorButton_clicked();
void on_equalButton_clicked();
void on_clearButton_clicked();
void on_backspaceButton_clicked();
protected:
void keyPressEvent(QKeyEvent *event);
};
#endif // MAINWINDOW_H
```
mainwindow.cpp:
```c++
#include "mainwindow.h"
#include "ui_mainwindow.h"
#include <QKeyEvent>
double calcResult(double leftOperand, double rightOperand, char op);
MainWindow::MainWindow(QWidget *parent)
: QMainWindow(parent)
, ui(new Ui::MainWindow)
{
ui->setupUi(this);
ui->resultLineEdit->setText("0.0");
}
MainWindow::~MainWindow()
{
delete ui;
}
void MainWindow::on_digitButton_clicked()
{
QPushButton *clickedButton = qobject_cast<QPushButton *>(sender());
QString digitValue = clickedButton->text();
QString currentValue = ui->resultLineEdit->text();
if (currentValue == "0.0") {
ui->resultLineEdit->setText(digitValue);
} else {
ui->resultLineEdit->setText(currentValue + digitValue);
}
}
void MainWindow::on_operatorButton_clicked()
{
QPushButton *clickedButton = qobject_cast<QPushButton *>(sender());
ui->operatorLineEdit->setText(clickedButton->text());
ui->leftOperandLineEdit->setText(ui->resultLineEdit->text());
ui->resultLineEdit->setText("0.0");
}
void MainWindow::on_equalButton_clicked()
{
QString leftOperandStr = ui->leftOperandLineEdit->text();
QString rightOperandStr = ui->resultLineEdit->text();
QString operatorStr = ui->operatorLineEdit->text();
double leftOperand = leftOperandStr.toDouble();
double rightOperand = rightOperandStr.toDouble();
double result = calcResult(leftOperand, rightOperand, operatorStr.toStdString()[0]);
ui->resultLineEdit->setText(QString::number(result));
ui->leftOperandLineEdit->setText(QString::number(result));
ui->operatorLineEdit->setText("");
}
void MainWindow::on_clearButton_clicked()
{
ui->leftOperandLineEdit->setText("");
ui->operatorLineEdit->setText("");
ui->resultLineEdit->setText("0.0");
}
void MainWindow::on_backspaceButton_clicked()
{
QString currentValue = ui->resultLineEdit->text();
if (currentValue.length() > 1) {
ui->resultLineEdit->setText(currentValue.left(currentValue.length() - 1));
} else {
ui->resultLineEdit->setText("0.0");
}
}
void MainWindow::keyPressEvent(QKeyEvent *event)
{
switch (event->key()) {
case Qt::Key_0:
ui->digitButton_0->click();
break;
case Qt::Key_1:
ui->digitButton_1->click();
break;
case Qt::Key_2:
ui->digitButton_2->click();
break;
case Qt::Key_3:
ui->digitButton_3->click();
break;
case Qt::Key_4:
ui->digitButton_4->click();
break;
case Qt::Key_5:
ui->digitButton_5->click();
break;
case Qt::Key_6:
ui->digitButton_6->click();
break;
case Qt::Key_7:
ui->digitButton_7->click();
break;
case Qt::Key_8:
ui->digitButton_8->click();
break;
case Qt::Key_9:
ui->digitButton_9->click();
break;
case Qt::Key_Plus:
ui->operatorButton_plus->click();
break;
case Qt::Key_Minus:
ui->operatorButton_minus->click();
break;
case Qt::Key_Asterisk:
ui->operatorButton_multiply->click();
break;
case Qt::Key_Slash:
ui->operatorButton_divide->click();
break;
case Qt::Key_Equal:
case Qt::Key_Return:
ui->equalButton->click();
break;
case Qt::Key_C:
ui->clearButton->click();
break;
case Qt::Key_Backspace:
ui->backspaceButton->click();
break;
default:
QMainWindow::keyPressEvent(event);
break;
}
}
double calcResult(double leftOperand, double rightOperand, char op)
{
switch (op) {
case '+':
return leftOperand + rightOperand;
case '-':
return leftOperand - rightOperand;
case '*':
return leftOperand * rightOperand;
case '/':
return leftOperand / rightOperand;
default:
return 0.0;
}
}
```
在该程序中,我们通过键盘事件来实现计算器的基本操作,包括输入数字、运算符、等号、清除和退格等。我们在主窗口类中重载了keyPressEvent()函数,根据用户按下的键来触发相应的按钮事件。同时,我们还定义了一些槽函数,用于处理按钮的点击事件。在这些函数中,我们可以通过获取对应按钮的指针来获取用户输入的值,并进行相应的计算和操作。
需要注意的是,在计算器程序中,我们需要定义一个calcResult()函数来计算用户输入的表达式的结果。在该函数中,我们通过switch语句来判断用户输入的运算符,并进行相应的计算。
用Java实现实现计算器,backspace为退格键,单目运算符:+/-,1/x,sqrt,%双目运算符:+,-,*,/。CE为清除,C为清除全部,M+,M-,MR,MC,M+表示将当前显示的存储数值进行加法运算
以下是一个简单的Java计算器实现,包括上述要求的功能:
```java
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
public class Calculator extends JFrame implements ActionListener {
private static final long serialVersionUID = 1L;
private JButton display;
private JButton backspace;
private JButton plusMinus;
private JButton reciprocal;
private JButton squareRoot;
private JButton percent;
private JButton clearEntry;
private JButton clearAll;
private JButton memoryPlus;
private JButton memoryMinus;
private JButton memoryRecall;
private JButton memoryClear;
private JButton divide;
private JButton multiply;
private JButton subtract;
private JButton add;
private JButton equals;
private double memory = 0;
private double currentNumber = 0;
private double result = 0;
private char lastOperator;
private boolean startNewNumber = true;
public Calculator() {
super("Calculator");
display = new JButton("0");
display.setEnabled(false);
backspace = new JButton("Backspace");
backspace.addActionListener(this);
plusMinus = new JButton("+/-");
plusMinus.addActionListener(this);
reciprocal = new JButton("1/x");
reciprocal.addActionListener(this);
squareRoot = new JButton("sqrt");
squareRoot.addActionListener(this);
percent = new JButton("%");
percent.addActionListener(this);
clearEntry = new JButton("CE");
clearEntry.addActionListener(this);
clearAll = new JButton("C");
clearAll.addActionListener(this);
memoryPlus = new JButton("M+");
memoryPlus.addActionListener(this);
memoryMinus = new JButton("M-");
memoryMinus.addActionListener(this);
memoryRecall = new JButton("MR");
memoryRecall.addActionListener(this);
memoryClear = new JButton("MC");
memoryClear.addActionListener(this);
divide = new JButton("/");
divide.addActionListener(this);
multiply = new JButton("*");
multiply.addActionListener(this);
subtract = new JButton("-");
subtract.addActionListener(this);
add = new JButton("+");
add.addActionListener(this);
equals = new JButton("=");
equals.addActionListener(this);
JPanel buttonPanel = new JPanel(new GridLayout(5, 4, 5, 5));
buttonPanel.add(memoryClear);
buttonPanel.add(memoryRecall);
buttonPanel.add(memoryMinus);
buttonPanel.add(memoryPlus);
buttonPanel.add(percent);
buttonPanel.add(squareRoot);
buttonPanel.add(reciprocal);
buttonPanel.add(divide);
buttonPanel.add(7);
buttonPanel.add(8);
buttonPanel.add(9);
buttonPanel.add(multiply);
buttonPanel.add(4);
buttonPanel.add(5);
buttonPanel.add(6);
buttonPanel.add(subtract);
buttonPanel.add(1);
buttonPanel.add(2);
buttonPanel.add(3);
buttonPanel.add(add);
buttonPanel.add(plusMinus);
buttonPanel.add(0);
buttonPanel.add(".");
buttonPanel.add(equals);
buttonPanel.add(clearEntry);
buttonPanel.add(clearAll);
buttonPanel.add(backspace);
JPanel displayPanel = new JPanel(new BorderLayout());
displayPanel.add(display, BorderLayout.CENTER);
add(displayPanel, BorderLayout.NORTH);
add(buttonPanel, BorderLayout.CENTER);
setSize(300, 300);
setLocationRelativeTo(null);
setResizable(false);
setDefaultCloseOperation(EXIT_ON_CLOSE);
}
private void handleNumberInput(int number) {
if (startNewNumber) {
display.setText(String.valueOf(number));
currentNumber = number;
startNewNumber = false;
} else {
String current = display.getText();
if (current.equals("0")) {
display.setText(String.valueOf(number));
} else {
display.setText(current + number);
}
currentNumber = Double.parseDouble(display.getText());
}
}
private void handleOperatorInput(char operator) {
if (startNewNumber) {
lastOperator = operator;
} else {
switch (lastOperator) {
case '+':
result += currentNumber;
break;
case '-':
result -= currentNumber;
break;
case '*':
result *= currentNumber;
break;
case '/':
result /= currentNumber;
break;
case '%':
result %= currentNumber;
break;
default:
result = currentNumber;
break;
}
display.setText(String.valueOf(result));
currentNumber = result;
startNewNumber = true;
lastOperator = operator;
}
}
public void actionPerformed(ActionEvent e) {
Object source = e.getSource();
if (source == backspace) {
String current = display.getText();
if (current.length() > 1) {
display.setText(current.substring(0, current.length() - 1));
currentNumber = Double.parseDouble(display.getText());
} else {
display.setText("0");
currentNumber = 0;
startNewNumber = true;
}
} else if (source == plusMinus) {
currentNumber = -currentNumber;
display.setText(String.valueOf(currentNumber));
} else if (source == reciprocal) {
currentNumber = 1 / currentNumber;
display.setText(String.valueOf(currentNumber));
} else if (source == squareRoot) {
currentNumber = Math.sqrt(currentNumber);
display.setText(String.valueOf(currentNumber));
} else if (source == percent) {
handleOperatorInput('%');
} else if (source == clearEntry) {
display.setText("0");
currentNumber = 0;
startNewNumber = true;
} else if (source == clearAll) {
result = 0;
lastOperator = ' ';
display.setText("0");
currentNumber = 0;
startNewNumber = true;
} else if (source == memoryPlus) {
memory += currentNumber;
} else if (source == memoryMinus) {
memory -= currentNumber;
} else if (source == memoryRecall) {
currentNumber = memory;
display.setText(String.valueOf(currentNumber));
} else if (source == memoryClear) {
memory = 0;
} else if (source == divide) {
handleOperatorInput('/');
} else if (source == multiply) {
handleOperatorInput('*');
} else if (source == subtract) {
handleOperatorInput('-');
} else if (source == add) {
handleOperatorInput('+');
} else if (source == equals) {
switch (lastOperator) {
case '+':
result += currentNumber;
break;
case '-':
result -= currentNumber;
break;
case '*':
result *= currentNumber;
break;
case '/':
result /= currentNumber;
break;
case '%':
result %= currentNumber;
break;
default:
result = currentNumber;
break;
}
display.setText(String.valueOf(result));
currentNumber = result;
startNewNumber = true;
lastOperator = ' ';
} else {
handleNumberInput((Integer) source);
}
}
public static void main(String[] args) {
Calculator calculator = new Calculator();
calculator.setVisible(true);
}
}
```
这个实现使用了Java的Swing GUI库来创建一个带有按钮和文本框的窗口,并在按钮上添加了相应的事件处理程序来实现计算器的功能。