三、具体实验步骤
1、先根据需求分析设计流程图,如下:
加减乘除功能的具体流程图,如下
2、根据流程图编写代码
先完成简易计算器实现加减乘除的算法
代码如下
package cn.lidan.start;
import cn.lidan.util.Const;
import jdk.nashorn.internal.objects.NativeString;
import javax.swing.*;
import java.awt.*;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
public class Carculator extends JFrame implements ActionListener {
//北面控件
private JPanel jp_north = new JPanel();
private JTextField input_text = new JTextField();
private JButton c_Btu = new JButton("C");
//中间的控件
private JPanel jp_center = new JPanel();
private NativeString btn_text;
public Carculator() throws HeadlessException {
this.init();
this.addNorthComponent();
this.addCenterButton();
}
//初始化的方法
public void init(){
this.setTitle(Const.TITLE);
this.setSize(Const.FRAME_W,Const.FRAME_H);
this.setLayout(new BorderLayout());
this.setLocation(Const.FRAME_X,Const.FRAME_Y);//窗口固定到中心点位置
this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
}
//添加北面的控件
public void addNorthComponent(){
this.input_text.setPreferredSize(new Dimension(230,30));
jp_north.add(input_text);
this.c_Btu.setForeground(Color.red);
jp_north.add(c_Btu);
c_Btu.addActionListener(new ActionListener() {
@Override
public void actionPerformed(ActionEvent e) {
input_text.setText("");
}
});
this.add(jp_north,BorderLayout.NORTH);
}
//添加中间按钮
public void addCenterButton(){
String btn_text = "123+456-789*.0=/C√()";//按键内容
String regex = "[\\+\\-*/.=C√()]";
this.jp_center.setLayout(new GridLayout(5,4));//中间键的个数
for(int i=0;i<20;i++){
String temp = btn_text.substring(i,i+1);
JButton btn = new JButton();
btn.setText(temp);
if(temp.matches(regex)){
btn.setFont(new Font("粗体",Font.BOLD, 20));
btn.setForeground(Color.red);
}
btn.addActionListener(this);
jp_center.add(btn);
}
this.add(jp_center,BorderLayout.CENTER);
}
public static void main(String[] args) {
Carculator carculator = new Carculator();
carculator.setVisible(true);
}
private String firstInput = null;
private String operator = null;
@Override
public void actionPerformed(ActionEvent e) {
String clickStr = e.getActionCommand();
if(".0123456789".indexOf(clickStr) != -1) {
this.input_text.setText(input_text.getText() + clickStr);
this.input_text.setHorizontalAlignment(JTextField.RIGHT);
// JOptionPane.showMessageDialog(this, clickStr);
}else if(clickStr.matches("[\\+\\-*/]{1}")){
operator = clickStr;
firstInput =this.input_text.getText();
this.input_text.setText("");
}else if(clickStr.equals("=")){
Double a = Double.valueOf(firstInput);
Double b = Double.valueOf(this.input_text.getText());
Double result = null;
switch (operator){
case "+":
result = a+b;
break;
case "-":
result = a-b;
break;
case "*":
result = a*b;
break;
case "/":
if(b!=0){
result =a/b;
}
break;
case "C":
input_text.setText(" ");
break;
}
this.input_text.setText(result.toString());
}
}
}
package cn.lidan.util;
import java.awt.*;
public class Const {
public static final int FRAME_W = 300;
public static final int FRAME_H = 300;
public static final int SCREEN_W = Toolkit.getDefaultToolkit().getScreenSize().width;
public static final int SCREEN_H = Toolkit.getDefaultToolkit().getScreenSize().height;
public static final int FRAME_X = (SCREEN_W - FRAME_W)/2;
public static final int FRAME_Y = (SCREEN_H - FRAME_H)/2;
public static final String TITLE = "计算器";
}
此时的运行结果如下:
6+6=12.0
6*6=36.0
8-2=6
10/5=2
3、新建包编写牛顿迭代法开方的代码,并导入前面已完成简易计算器代码中,实现计算器的开方功能,重要代码如下
package sxj; import java.util.Scanner; public class Niudun { public static void main(String args[]){ Scanner s = new Scanner(System.in); System.out.println("请输入一个非负整数"); int c = s.nextInt(); if (c<0){ System.out.println("负数无法开方"); System.out.println("输入有误!"); }else{ double x1,x0 =c; double fx=2*x0; x1 =x0 -(x0*x0-c)/fx; while(Math.abs(x1-x0)>1e-16){ x0=x1; x1=x0-(x0*x0-c)/fx; } System.out.println(c+"的算术平方根是"+x1+"和"+x0); } } }
将代码整合,最后实现计算器加减乘除和牛顿迭代算法的功能,试运行结果如下:
7√=2.6
四、总结
经过本次实验,熟练掌握了软件开发的基本流程,软件设计和开发的基本工具,对集成软件开发环境在软件开发过程中的作用有了更深入的理解。