Community Learn Tools Library Leisure
search
English
Home > Java > javaTutorial > Summary of common methods for writing calculators in Java

Summary of common methods for writing calculators in Java

高洛峰
Release： 2017-01-20 16:58:18
Original
1754 people have browsed it

The examples in this article summarize common methods of writing calculators in Java. Share it with everyone for your reference, the details are as follows:

Method one: 

package wanwa;
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
public class Calculator extends JFrame {
private Container container;
private GridBagLayout layout;
private GridBagConstraints constraints;
private JTextField displayField;// 计算结果显示区
private String lastCommand;// 保存+,-,*,/,=命令
private double result;// 保存计算结果
private boolean start;// 判断是否为数字的开始
public Calculator() {
super("Calculator");
container = getContentPane();
layout = new GridBagLayout();
container.setLayout(layout);
constraints = new GridBagConstraints();
start = true;
result = 0;
lastCommand = "=";
displayField = new JTextField(20);
displayField.setHorizontalAlignment(JTextField.RIGHT);
constraints.gridx = 0;
constraints.gridy = 0;
constraints.gridwidth = 4;
constraints.gridheight = 1;
constraints.fill = GridBagConstraints.BOTH;
constraints.weightx = 100;
constraints.weighty = 100;
layout.setConstraints(displayField, constraints);
container.add(displayField);
ActionListener insert = new InsertAction();
ActionListener command = new CommandAction();
// addButton("Backspace", 0, 1, 2, 1, insert);
// addButton("CE", 2, 1, 1, 1, insert);
// addButton("C", 3, 1, 1, 1, insert);
addButton("7", 0, 2, 1, 1, insert);
addButton("8", 1, 2, 1, 1, insert);
addButton("9", 2, 2, 1, 1, insert);
addButton("/", 3, 2, 1, 1, command);
addButton("4", 0, 3, 1, 1, insert);
addButton("5", 1, 3, 1, 1, insert);
addButton("6", 2, 3, 1, 1, insert);
addButton("*", 3, 3, 1, 1, command);
addButton("1", 0, 4, 1, 1, insert);
addButton("2", 1, 4, 1, 1, insert);
addButton("3", 2, 4, 1, 1, insert);
addButton("-", 3, 4, 1, 1, command);
addButton("0", 0, 5, 1, 1, insert);
// addButton("+/-", 1, 5, 1, 1, insert);// 只显示"-"号,"+"没有实用价值
addButton(".", 2, 5, 1, 1, insert);
addButton("+", 3, 5, 1, 1, command);
addButton("=", 0, 6, 4, 1, command);
this.setResizable(false);
setSize(180, 200);
setVisible(true);
}
private void addButton(String label, int row, int column, int with,
int height, ActionListener listener) {
JButton button = new JButton(label);
constraints.gridx = row;
constraints.gridy = column;
constraints.gridwidth = with;
constraints.gridheight = height;
constraints.fill = GridBagConstraints.BOTH;
button.addActionListener(listener);
layout.setConstraints(button, constraints);
container.add(button);
}
private class InsertAction implements ActionListener {
public void actionPerformed(ActionEvent event) {
String input = event.getActionCommand();
if (start) {
displayField.setText("");
start = false;
if (input.equals("+/-"))
displayField.setText(displayField.getText() + "-");
}
if (!input.equals("+/-")) {
  if (input.equals("Backspace")) {
   String str = displayField.getText();
if (str.length() > 0)
  displayField.setText(str.substring(0, str.length() - 1));
} else if (input.equals("CE") || input.equals("C")) {
displayField.setText("0");
start = true;
} else
displayField.setText(displayField.getText() + input);
}
}
}
private class CommandAction implements ActionListener {
 public void actionPerformed(ActionEvent evt) {
 String command = evt.getActionCommand();
 if (start) {
 lastCommand = command;
 } else {
 calculate(Double.parseDouble(displayField.getText()));
 lastCommand = command;
 start = true;
 }
}
}
public void calculate(double x) {
if (lastCommand.equals("+"))
result += x;
else if (lastCommand.equals("-"))
result -= x;
else if (lastCommand.equals("*"))
result *= x;
else if (lastCommand.equals("/"))
result /= x;
else if (lastCommand.equals("="))
result = x;
displayField.setText("" + result);
}
public static void main(String[] args) {
Calculator calculator = new Calculator();
calculator.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
}
}
Copy after login

Method two: 

import java.awt.*;
import java.awt.event.*;
public class MyCalculator {
 PRivate Frame f;
 private TextField tf = new TextField(30);
 private long result;
 private boolean append=false;
 private char Operator='=';
 private Button[] btn=new Button[15];
 public MyCalculator() {
  initComponent();
 }
 private void initComponent() {
  f = new Frame("My Calculator V1.0");
  f.setLayout(new BorderLayout()); //The frame uses BorderLayout
  f.addWindowListener(new WindowAdapter() {
   public void windowClosing(WindowEvent evt) {
    System.exit(0);
   }
  });
  Panel centerPanel = new Panel();
  centerPanel.setLayout(new GridLayout(5, 3)); //The panel uses GridLayout
  NumberListener nl=new NumberListener();
  OperatorListener ol=new OperatorListener();
  btn[10]=new Button("+");
  btn[11]=new Button("-");
  btn[12]=new Button("*");
  btn[13]=new Button("/");
  btn[14]=new Button("=");
  for (int i=0;i<=9;i++){
   btn[i]=new Button(String.valueOf(i));
   centerPanel.add(btn[i]);
   btn[i].addActionListener(nl);
   if (i%2==1){
    centerPanel.add(btn[(i+19)/2]);
    btn[(i+19)/2].addActionListener(ol);
   }
  }
  f.add(centerPanel, BorderLayout.CENTER);
  Panel northPanel = new Panel();
  tf.setEditable(false);
  northPanel.add(tf);
  f.add(northPanel, BorderLayout.NORTH);
 }
 public void go() {
  f.pack();
  f.setVisible(true);
 }
 public static void main(String[] args) {
  new MyCalculator().go();
 }
 /**
 *采用成员内部类方式，实现监听器接口，方便访问主类内类内部成员。
 *此类负责数字按钮Action事件监听和处理
 */
 class NumberListener implements ActionListener{
  public void actionPerformed(ActionEvent e){
   if (!append) {
    tf.setText("");
    append=true;
   }
   String s=tf.getText();
   s+=e.getActionCommand();
   tf.setText(s);
   if (!btn[10].isEnabled()){
    for(int i=10;i<=14;i++) btn[i].setEnabled(true);
   }
  }
 }
 /**
 * 成员内部类，负责操作符按钮的事件处理
 */
 class OperatorListener implements ActionListener{
  public void actionPerformed(ActionEvent e){
   if (!append) return;
   for(int i=10;i<=14;i++) btn[i].setEnabled(false);
   String s=tf.getText();
   long num=Long.parseLong(s);//get the number of textfield
   append=false; //set append
   switch(operator){
    case &#39;+&#39;:result+=num;break;
    case &#39;-&#39;:result-=num;break;
    case &#39;*&#39;:result*=num;break;
    case &#39;/&#39;:{
     if (num==0) result=0;
     else result/=num;
     break;
    }
    case &#39;=&#39;:result=num;break;
   }
   tf.setText(String.valueOf(result));
   //set the value of result to textfield
   String op=e.getActionCommand();
   operator=op.charAt(0); // set operator
  }
 }
}
Copy after login

Method three: 

package wanwa;
import java.util.*;
public class calc {
public static void main(String[] args) {
Scanner input = new Scanner(System.in);
System.out.println("*****************简易计算器****************");
System.out.println("*\t\t\t\t\t*");
System.out.println("* 使用说明： 1.加法 2.减法 3.乘法 4.除法 *");
System.out.println("*\t\t\t\t\t*");
System.out.println("*****************************************");
for(int i=0;i<100;i++){
System.out.print("\n请选择运算规则：");
int num = input.nextInt();
switch(num){
case 1:
System.out.println("\n******你选择了加法******\n");
System.out.print("请输入第1个加数:");
int jiashu1 = input.nextInt();
System.out.print("请输入第2个加数:");
int jiashu2 = input.nextInt();
System.out.println("运算结果为:" + jiashu1 + " + " + jiashu1 + " = " + (jiashu1 + jiashu2));
break;
case 2:
System.out.println("\n******你选择了减法******\n");
System.out.print("请输入被减数:");
int jianshu1 = input.nextInt();
System.out.print("请输入减数:");
int jianshu2 = input.nextInt();
System.out.println("运算结果为:" + jianshu1 + " - " + jianshu2 + " = " + (jianshu1 - jianshu2));
break;
case 3:
System.out.println("\n******你选择了乘法******\n");
System.out.print("请输入第1个因数:");
int chengfa1 = input.nextInt();
System.out.print("请输入第2个因数:");
int chengfa2 = input.nextInt();
System.out.println("运算结果为:" + chengfa1 + " * " + chengfa2 + " = " + (chengfa1 * chengfa2));
break;
case 4:
System.out.println("\n******你选择了除法******\n");
System.out.print("请输入被除数:");
double chufa1 = input.nextInt();
System.out.print("请输入除数:");
double chufa2 = input.nextInt();
System.out.println("运算结果为:" + chufa1 + " / " + chufa2 + " = " + (chufa1 / chufa2) + " 余 " + (chufa1 % chufa2));
break;
default:
System.out.println("\n你的选择有错，请重新选择!");
break;
}
}
}
}
Copy after login

Method four:

package wanwa;
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
public class Calculator extends JFrame {
private Container container;
private GridBagLayout layout;
private GridBagConstraints constraints;
private JTextField displayField;// 计算结果显示区
private String lastCommand;// 保存+,-,*,/,=命令
private double result;// 保存计算结果
private boolean start;// 判断是否为数字的开始
public Calculator() {
super("Calculator");
container = getContentPane();
layout = new GridBagLayout();
container.setLayout(layout);
constraints = new GridBagConstraints();
start = true;
result = 0;
lastCommand = "=";
displayField = new JTextField(20);
displayField.setHorizontalAlignment(JTextField.RIGHT);
constraints.gridx = 0;
constraints.gridy = 0;
constraints.gridwidth = 4;
constraints.gridheight = 1;
constraints.fill = GridBagConstraints.BOTH;
constraints.weightx = 100;
constraints.weighty = 100;
layout.setConstraints(displayField, constraints);
container.add(displayField);
ActionListener insert = new InsertAction();
ActionListener command = new CommandAction();
// addButton("Backspace", 0, 1, 2, 1, insert);
// addButton("CE", 2, 1, 1, 1, insert);
// addButton("C", 3, 1, 1, 1, insert);
addButton("7", 0, 2, 1, 1, insert);
addButton("8", 1, 2, 1, 1, insert);
addButton("9", 2, 2, 1, 1, insert);
addButton("/", 3, 2, 1, 1, command);
addButton("4", 0, 3, 1, 1, insert);
addButton("5", 1, 3, 1, 1, insert);
addButton("6", 2, 3, 1, 1, insert);
addButton("*", 3, 3, 1, 1, command);
addButton("1", 0, 4, 1, 1, insert);
addButton("2", 1, 4, 1, 1, insert);
addButton("3", 2, 4, 1, 1, insert);
addButton("-", 3, 4, 1, 1, command);
addButton("0", 0, 5, 1, 1, insert);
// addButton("+/-", 1, 5, 1, 1, insert);// 只显示"-"号,"+"没有实用价值
addButton(".", 2, 5, 1, 1, insert);
addButton("+", 3, 5, 1, 1, command);
addButton("=", 0, 6, 4, 1, command);
this.setResizable(false);
setSize(180, 200);
setVisible(true);
}
private void addButton(String label, int row, int column, int with,
int height, ActionListener listener) {
JButton button = new JButton(label);
constraints.gridx = row;
constraints.gridy = column;
constraints.gridwidth = with;
constraints.gridheight = height;
constraints.fill = GridBagConstraints.BOTH;
button.addActionListener(listener);
layout.setConstraints(button, constraints);
container.add(button);
}
private class InsertAction implements ActionListener {
public void actionPerformed(ActionEvent event) {
String input = event.getActionCommand();
if (start) {
displayField.setText("");
start = false;
if (input.equals("+/-"))
displayField.setText(displayField.getText() + "-");
}
if (!input.equals("+/-")) {
  if (input.equals("Backspace")) {
   String str = displayField.getText();
if (str.length() > 0)
  displayField.setText(str.substring(0, str.length() - 1));
} else if (input.equals("CE") || input.equals("C")) {
displayField.setText("0");
start = true;
} else
displayField.setText(displayField.getText() + input);
}
}
}
private class CommandAction implements ActionListener {
 public void actionPerformed(ActionEvent evt) {
 String command = evt.getActionCommand();
 if (start) {
 lastCommand = command;
 } else {
 calculate(Double.parseDouble(displayField.getText()));
 lastCommand = command;
 start = true;
 }
}
}
public void calculate(double x) {
if (lastCommand.equals("+"))
result += x;
else if (lastCommand.equals("-"))
result -= x;
else if (lastCommand.equals("*"))
result *= x;
else if (lastCommand.equals("/"))
result /= x;
else if (lastCommand.equals("="))
result = x;
displayField.setText("" + result);
}
public static void main(String[] args) {
Calculator calculator = new Calculator();
calculator.setDefaultCloSEOperation(JFrame.EXIT_ON_CLOSE);
}
}
Copy after login

I hope this article will be helpful to everyone in Java programming.

For more examples and summary of common methods of writing calculators in Java, please pay attention to the PHP Chinese website for related articles!

Related labels：
Java 计算器
source：php.cn
Previous article：Java object simple practical case calculator implementation code Next article：Java implements Android calculator code with brackets
Statement of this Website
The content of this article is voluntarily contributed by netizens, and the copyright belongs to the original author. This site does not assume corresponding legal responsibility. If you find any content suspected of plagiarism or infringement, please contact admin@php.cn
Latest Articles by Author
Latest Issues
SQL Count() also requires 0 I have only one table and I want to count each entry of a tag that starts with 0. Now I tr...
From 2024-04-06 19:48:53
0
1
449
Calculate the sum of fields in another table using MySQL SQL query I have a schema like this: User table with attributes "user_id" and "userna...
From 2024-04-06 19:39:29
0
1
441
Open calculation documents using window.open() and data: scheme I have a web page that runs in a browser that generates a calculated HTML document that I ...
From 2024-04-06 15:06:34
0
1
378
Launch a transparent browser to improve the experience of web applications and PWA [support static HTML, CSS and JavaScript] [allow users to view desktop wallpapers in our web applications/PWA] I'm a junior front-end developer and designer currently developing a web application (chat...
From 2024-04-05 13:50:12
0
1
1367
Can PDF files run HTML5 and Javascript? I have a stupid idea to try and make a program that won't be blocked on any computer since...
From 2024-04-05 12:57:00
0
1
456
Related Topics
More>
Popular Recommendations
Popular Tutorials
More>
Related Tutorials
Popular Recommendations
Latest courses
Latest Downloads
More>
Web Effects
Website Source Code
Website Materials
Front End Template