java_calculator.rar_java 计算器_java_calculator_四则计算器_计算器_计算器 java

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); setSize(300,300); 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); } }