Java编写计算器的常见方法实例总结

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;} elsedisplayField.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);}}

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 '+':result+=num;break;    case '-':result-=num;break;    case '*':result*=num;break;    case '/':{     if (num==0) result=0;     else result/=num;     break;    }    case '=':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  } }}

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;}}}}

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;} elsedisplayField.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);}}