Ⅰ java 写的计算器源代码只实现加减乘除四则运算即可
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import java.util.Vector;
public class calculator
{
String str1="0"; //运算数1 初值一定为0 为了程序的安全
String str2="0"; //运算数2
String fh="+"; //运算符
String jg="";//结果
//状态开关 重要
int k1=1;//开关1 用于选择输入方向 将要写入str2或 str2
int k2=1;//开关2 符号键 次数 k2>1说明进行的是2+3-9+8 这样的多符号运算
int k3=1;//开关3 str1 是否可以被清0 ==1时可以 !=1时不能被清0
int k4=1;//开关4 str2 同上
int k5=1;//开关5 控制小数点可否被录入 ==1时可以 !=1 输入的小数点被丢掉
JButton jicunqi; //寄存器 记录 是否连续按下符号键
Vector vt=new Vector(20,10);
JFrame frame=new JFrame("sunshine---计算器");
JTextField jg_TextField=new JTextField(jg,20);//20列
JButton clear_Button=new JButton("清除");
JButton button0=new JButton("0");
JButton button1=new JButton("1");
JButton button2=new JButton("2");
JButton button3=new JButton("3");
JButton button4=new JButton("4");
JButton button5=new JButton("5");
JButton button6=new JButton("6");
JButton button7=new JButton("7");
JButton button8=new JButton("8");
JButton button9=new JButton("9");
JButton button_Dian=new JButton(".");
JButton button_jia=new JButton("+");
JButton button_jian=new JButton("-");
JButton button_cheng=new JButton("*");
JButton button_chu=new JButton("/");
JButton button_dy=new JButton("=");
public static void main(String[] args)
{
calculator calculator=new calculator();
}
calculator()
{
jg_TextField.setHorizontalAlignment(JTextField.RIGHT );//文本框 右对齐
JPanel pan=new JPanel();
pan.setLayout(new GridLayout(4,4,5,5));//四行四列 边距为5像素
pan.add(button7);
pan.add(button8);
pan.add(button9);
pan.add(button_chu);
pan.add(button4);
pan.add(button5);
pan.add(button6);
pan.add(button_cheng);
pan.add(button1);
pan.add(button2);
pan.add(button3);
pan.add(button_jian);
pan.add(button0);
pan.add(button_Dian);
pan.add(button_dy);
pan.add(button_jia);
pan.setBorder(BorderFactory.createEmptyBorder(5,5,5,5));//pan对象的边距
JPanel pan2=new JPanel();
pan2.add(jg_TextField);
JPanel pan3=new JPanel(); //为什么要 多此一句呢？ 因为我不会设置 按钮的大小
pan3.setLayout(new FlowLayout());
pan3.add(clear_Button);
//clear_Button.setSize(10,10);//设置清零按钮的大小 吗的 不好使 ！！
frame.setLocation(300, 200); //主窗口 出现在位置
frame.setResizable(false); //不能调大小
frame.getContentPane().setLayout(new BorderLayout());
frame.getContentPane().add(pan2,BorderLayout.NORTH);
frame.getContentPane().add(pan,BorderLayout.CENTER);
frame.getContentPane().add(pan3,BorderLayout.SOUTH);
frame.pack();
frame.setVisible(true);
//以上是 控件 和 布局
//下面是事件处理 程 序
//--------------- 数 字 键 ----------------
class JianTing implements ActionListener
{
public void actionPerformed(ActionEvent e)
{
String ss=((JButton)e.getSource()).getText();
jicunqi=(JButton)e.getSource();
vt.add(jicunqi);
if (k1==1)
{
if(k3==1)
{
str1="";
k5=1;//还原开关k5状态
}
str1=str1+ss;
//k2=1;
k3=k3+1;
//System.out.println(str1);
jg_TextField.setText(str1);//显示
}
else if(k1==2)
{
if (k4==1)
{
str2="";
k5=1; //还原开关k5状态
}
str2=str2+ss;
//k2=2;
k4=k4+1;
///////////////测试////////////////
jg_TextField.setText(str2);
}
}
}
//－－－－－－－－符 号－－－－－－－－－－－
class JianTing_fh implements ActionListener
{
public void actionPerformed(ActionEvent e)
{
String ss2=((JButton)e.getSource()).getText();
jicunqi=(JButton)e.getSource();
vt.add(jicunqi);
if(k2==1)
{
k1=2;//开关 k1 为1时,向数1写 为2时，向数2写
k5=1;
fh=ss2;
k2=k2+1;//按符号键的次数
}
else
{
int a=vt.size();
JButton c=(JButton)vt.get(a-2); if(!(c.getText().equals("+"))&&!(c.getText().equals("-"))&&!(c.getText().equals("*"))&&!(c.getText().equals("/")))
{
yuns();
str1=jg;
k1=2;//开关 k1 为1时,向数1写 为2时，向数2写
k5=1;
k4=1;
fh=ss2;
} k2=k2+1;
}
}
}
//－－－－－－－－清除－－－－－－－
class JianTing_clear implements ActionListener
{
public void actionPerformed(ActionEvent e)
{
jicunqi=(JButton)e.getSource();
vt.add(jicunqi);
k5=1;
k2=1;
k1=1;
k3=1;
k4=1;
str1="0";
str2="0";
fh="";
jg="";
jg_TextField.setText(jg);
vt.clear();
}
}
//----------------等 于 ---------------------
class JianTing_dy implements ActionListener
{
public void actionPerformed(ActionEvent e)
{
jicunqi=(JButton)e.getSource();
vt.add(jicunqi);
yuns();
k1=1; //还原开关k1状态
//str1=jg;
k2=1;
k3=1;//还原开关k3状态
k4=1; //还原开关k4状态
str1=jg; //为7+5=12 +5=17 这种计算做准备
}
}
//----------------小数点 ---------------------
class JianTing_xiaos implements ActionListener
{
public void actionPerformed(ActionEvent e)
{
jicunqi=(JButton)e.getSource();
vt.add(jicunqi);
if(k5==1)
{
String ss2=((JButton)e.getSource()).getText();
if (k1==1)
{
if(k3==1)
{
str1="";
k5=1; //还原开关k5状态
}
str1=str1+ss2;
//k2=1;
k3=k3+1;
//System.out.println(str1);
jg_TextField.setText(str1);//显示
}
else if(k1==2)
{
if (k4==1)
{
str2="";
k5=1; //还原开关k5状态
}
str2=str2+ss2;
//k2=2;
k4=k4+1;
///////////////测试////////////////
jg_TextField.setText(str2);
}
}
k5=k5+1;
}
}
//注册 监听器
JianTing_dy jt_dy=new JianTing_dy();
JianTing jt= new JianTing();//临听数字键
JianTing_fh jt_fh= new JianTing_fh();//临 听符 号键
JianTing_clear jt_c=new JianTing_clear(); //清除键
JianTing_xiaos jt_xs=new JianTing_xiaos();// 小数点 键
button7.addActionListener(jt);
button8.addActionListener(jt);
button9.addActionListener(jt);
button_chu.addActionListener(jt_fh);
button4.addActionListener(jt);
button5.addActionListener(jt);
button6.addActionListener(jt);
button_cheng.addActionListener(jt_fh);
button1.addActionListener(jt);
button2.addActionListener(jt);
button3.addActionListener(jt);
button_jian.addActionListener(jt_fh);
button0.addActionListener(jt);
button_Dian.addActionListener(jt_xs);
button_dy.addActionListener(jt_dy);
button_jia.addActionListener(jt_fh);
clear_Button.addActionListener(jt_c);
//关闭事件处理程序
frame.addWindowListener(new WindowAdapter()
{
public void windowClosing(WindowEvent e)
{
System.exit(0);
}
});
}
//---------------计 算------------------
public void yuns()
{
double a2,b2;//运算数1,2
String c=fh;// 运算符
double jg2=0 ;//结果
if (c.equals(""))
{
//System.out.println("请输入运算符");
jg_TextField.setText("请输入运算符");
}
else
{
System.out.println("str1:"+str1);//调试时 使 用
System.out.println("str2:"+str2);//调试时 使 用
System.out.println("运算符:"+fh);//调试时 使 用
if (str1.equals(".")) //字符串 "." 转换成double型数据时 会出错 所以手工转
str1="0.0";
if (str2.equals("."))
str2="0.0";
a2=Double.valueOf(str1).doubleValue();
b2=Double.valueOf(str2).doubleValue();
System.out.println("double型的a2："+a2); //调试时 使 用
System.out.println("double型的b2："+b2); //调试时 使 用
if (c.equals("+"))
{
jg2=a2+b2;
}
if (c.equals("-"))
{
jg2=a2-b2;
}
if (c.equals("*"))
{
jg2=a2*b2;
}
if (c.equals("/"))
{
if(b2==0)
{
jg2=0;//0000000000000 by 0 cu!
}
else
{
jg2=a2/b2;
}
}
System.out.println("double型a2"+fh+"b2结果："+jg2);
System.out.println();
jg=((new Double(jg2)).toString());
jg_TextField.setText(jg);
}
}
}
Ⅱ java编一个计算器的代码
界面漂亮堪比系统自带计算器，功能完美加减乘除开平方等等全部具备，还有清零按钮，小数点的使用，连加连乘功能完全参考系统官方计算器经过长期调试改进而成，马上拷贝代码拿去试试看吧，绝不后悔！
代码如下：
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import java.util.*;
public class Counter {
public static void main(String[] args) {
CounterFrame frame = new CounterFrame();
frame.show();
}
}
class CounterFrame extends JFrame {
public CounterFrame() {
JMenuBar menuBar = new JMenuBar();
JMenu menuFile = new JMenu();
JMenu menuFile1 = new JMenu();
JMenu menuFile2 = new JMenu();
JMenu menuFile3 = new JMenu();
JMenuItem menuFileExit = new JMenuItem();
menuFile.setText("文件");
menuFile1.setText("编辑");
menuFile2.setText("查看");
menuFile3.setText("帮助");
menuFileExit.setText("退出");
menuFileExit.addActionListener
(
new ActionListener() {
public void actionPerformed(ActionEvent e) {
CounterFrame.this.windowClosed();
}
}
);
menuFile.add(menuFileExit);
menuBar.add(menuFile);
menuBar.add(menuFile1);
menuBar.add(menuFile2);
menuBar.add(menuFile3);
setTitle("计算器");
setJMenuBar(menuBar);
setSize(new Dimension(400, 280));
this.getContentPane().add(new Allpanel());
this.addWindowListener
(
new WindowAdapter() {
public void windowClosing(WindowEvent e) {
CounterFrame.this.windowClosed();
}
}
);
}
protected void windowClosed() {
System.exit(0);
}
}
class Tool {
public static Tool instance;
private JTextField field;
private Tool() {
this.field=new JTextField(30);
this.field.setHorizontalAlignment(JTextField.RIGHT);
}
public static Tool getinstance()
{
if(instance==null)
{
instance=new Tool();
}
return instance;
}
public JTextField getfield()
{
return (this.field);
}
}
class Allpanel extends JPanel {
public Allpanel() {
this.setLayout(new BorderLayout(0,7));
Northpanel np=new Northpanel();
Centerpanel cp=new Centerpanel();
this.add(np,BorderLayout.NORTH);
this.add(cp,BorderLayout.CENTER);
}
}
class Centercenter extends JPanel {
static Vector Vec=new Vector();
static Vector vc=new Vector();
static Vector vc1=new Vector();
static Vector vc2=new Vector();
static Vector vc3=new Vector();
static String begin="yes";
static double add;
static double jq;
static double cs;
static double cq;
static double dy;
static String jg;
static String what;
static double tool=0;
static String to="yes";
/**
* Method Centercenter
*
*
*/
public Centercenter() {
// TODO: Add your code here
final JTextField text=Tool.getinstance().getfield();
this.setLayout(new GridLayout(4,5,3,3));
String arg[] ={"7","8","9","/","sqrt","4","5","6","*","%","1","2","3","-","1/x","0","+/-",".","+","="};
for(int i=0;i<20;i++)
{
final JButton b=new JButton(arg[i]);
//this.add(new JButton(arg[i]));
this.add(b);
if(i==0||i==1||i==2||i==5||i==6||i==7||i==10||i==11||i==12||i==15)
{
b.addActionListener(new ActionListener()
{
public void actionPerformed(ActionEvent e)
{
String mark=b.getText();
String ma=text.getText();
if(vc3.contains("v3"))
{
text.setText("0."+mark);
vc3.clear();
}
else if(vc.contains("a"))
{
if(vc2.contains("v2"))
{
text.setText("0."+mark);
vc.clear();
vc2.clear();
}
else
{
text.setText(mark);
vc.clear();
Vec.clear();
Vec.add(mark);
}
}
else
{
text.setText(ma.trim()+mark);
Vec.add(mark);
}
begin="no";
to="yes";
}
});
}
if(i==17)
{
b.addActionListener(new ActionListener()
{
public void actionPerformed(ActionEvent e)
{
String mar=b.getText();
String m=text.getText();
if("yes".equals(begin))
{
vc3.add("v3");
}
if(vc1.contains("v1"))
{
vc2.add("v2");
vc1.clear();
}
if(!Vec.contains(".")&&!vc.contains("a"))
{
text.setText(m.trim()+mar);
Vec.add(".");
}
}
});
}
if(i==18)
{
b.addActionListener(new ActionListener()
{
public void actionPerformed(ActionEvent e)
{
String ma=text.getText();
add=Double.parseDouble(ma);
if(what==null)
{
tool=add;
what="add";
}
else
{
tool=tool+add;
text.setText(String.valueOf((tool)));
}
vc.add("a");
vc1.add("v1");
to="+";
}
});
}
if(i==13)
{
b.addActionListener(new ActionListener()
{
public void actionPerformed(ActionEvent e)
{
String ma=text.getText();
jq=Double.parseDouble(ma);
if(what==null)
{
tool=jq;
what="jq";
}
else
{
tool=tool-jq;
text.setText(String.valueOf((tool)));
}
vc.add("a");
vc1.add("v1");
to="-";
}
});
}
if(i==3)
{
b.addActionListener(new ActionListener()
{
public void actionPerformed(ActionEvent e)
{
String ma=text.getText();
cq=Double.parseDouble(ma);
if(what==null)
{
tool=cq;
what="cq";
}
else
{
tool=tool/cq;
text.setText(String.valueOf((tool)));
}
vc.add("a");
vc1.add("v1");
to="/";
}
});
}
if(i==4)
{
b.addActionListener(new ActionListener()
{
public void actionPerformed(ActionEvent e)
{
String ma=text.getText();
cq=Double.parseDouble(ma);
text.setText(String.valueOf(Math.sqrt(cq)));
}
});
}
if(i==8)
{
b.addActionListener(new ActionListener()
{
public void actionPerformed(ActionEvent e)
{
String ma=text.getText();
cs=Double.parseDouble(ma);
if(what==null)
{
tool=cs;
what="cs";
}
else
{
tool=tool*cs;
text.setText(String.valueOf((tool)));
}
vc.add("a");
vc1.add("v1");
to="*";
}
});
}
if(i==19)
{
b.addActionListener(new ActionListener()
{
public void actionPerformed(ActionEvent e)
{
String ma=text.getText();
dy=Double.parseDouble(ma);
if(what=="add")
{
jg=String.valueOf((tool+dy));
}
if(what=="jq")
{
jg=String.valueOf((tool-dy));
}
if(what=="cs")
{
jg=String.valueOf((tool*dy));
}
if(what=="cq")
{
jg=String.valueOf((tool/dy));
}
if(what==null)
{
if(to=="+")
{
tool=add;
jg=String.valueOf(tool+dy);
}
else if(to=="-")
{
tool=jq;
jg=String.valueOf(dy-tool);
}
else if(to=="*")
{
tool=cs;
jg=String.valueOf(dy*tool);
}
else if(to=="/")
{
tool=cq;
jg=String.valueOf(dy/tool);
}
else
{
jg=String.valueOf(dy);
}
}
text.setText(jg);
Vec.clear();
Vec.add(".");
vc.add("a");
vc1.add("v1");
what=null;
tool=0;
}
});
}
}
}
}
class Centernorth extends JPanel {
public Centernorth() {
final JTextField text=Tool.getinstance().getfield();
JButton jb1=new JButton("Backspace");
JButton jb2=new JButton(" CE ");
JButton jb3=new JButton(" C ");
this.add(jb1);
this.add(jb2);
this.add(jb3);
jb1.addActionListener(new ActionListener(){
public void actionPerformed(ActionEvent e)
{
String back=Tool.getinstance().getfield().getText();
text.setText(backmethod(back));
Centercenter.Vec.remove(Centercenter.Vec.size()-1);
}
});
jb3.addActionListener(new ActionListener(){
public void actionPerformed(ActionEvent e)
{
text.setText("0.");
Centercenter.Vec.clear();
Centercenter.Vec.add(".");
Centercenter.vc.add("a");
Centercenter.begin="yes";
Centercenter.vc1.clear();
Centercenter.what=null;
Centercenter.tool=0;
}
});
}
public String backmethod(String str)
{
return str.substring(0,str.length()-1);
}
}
class Centerpanel extends JPanel {
public Centerpanel() {
this.setLayout(new BorderLayout(8,7));
Centernorth cn=new Centernorth();
Centercenter cc=new Centercenter();
Centerwest cw=new Centerwest();
this.add(cn,BorderLayout.NORTH);
this.add(cc,BorderLayout.CENTER);
this.add(cw,BorderLayout.WEST);
}
}
class Centerwest extends JPanel {
public Centerwest() {
this.setLayout(new GridLayout(4,1,3,3));
this.add(new JButton("MC"));
this.add(new JButton("MR"));
this.add(new JButton("MS"));
this.add(new JButton("M+"));
}
}
class Northpanel extends JPanel {
private JTextField tf;
public Northpanel() {
tf=Tool.getinstance().getfield();
this.add(tf);
}
}
---------------------------------------------------------------------------
=============《按你要求特意后改过的最简单功能的代码如下》========================
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import java.util.*;
public class Counter2 {
public static void main(String[] args) {
CounterFrame frame = new CounterFrame();
frame.show();
}
}
class CounterFrame extends JFrame {
public CounterFrame() {
setTitle("计算器");
setSize(new Dimension(400, 280));
this.getContentPane().add(new Allpanel());
this.addWindowListener
(
new WindowAdapter() {
public void windowClosing(WindowEvent e) {
CounterFrame.this.windowClosed();
}
}
);
}
protected void windowClosed() {
System.exit(0);
}
}
class Tool {
public static Tool instance;
private JTextField field;
private Tool() {
this.field=new JTextField(30);
this.field.setHorizontalAlignment(JTextField.RIGHT);
}
public static Tool getinstance()
{
if(instance==null)
{
instance=new Tool();
}
return instance;
}
public JTextField getfield()
{
return (this.field);
}
}
class Allpanel extends JPanel {
public Allpanel() {
this.setLayout(new BorderLayout(0,7));
Northpanel np=new Northpanel();
Centerpanel cp=new Centerpanel();
this.add(np,BorderLayout.NORTH);
this.add(cp,BorderLayout.CENTER);
}
}
class Centercenter extends JPanel {
static Vector Vec=new Vector();
static Vector vc=new Vector();
static Vector vc1=new Vector();
static Vector vc2=new Vector();
static Vector vc3=new Vector();
static String begin="yes";
static double add;
static double jq;
static double cs;
static double cq;
static double dy;
static String jg;
static String what;
static double tool=0;
static String to="yes";
/**
* Method Centercenter
*
*
*/
public Centercenter() {
// TODO: Add your code here
final JTextField text=Tool.getinstance().getfield();
this.setLayout(new GridLayout(4,5,3,3));
String arg[] ={"7","8","9","/","4","5","6","*","1","2","3","-","0","=",".","+"};
for(int i=0;i<16;i++)
{
final JButton b=new JButton(arg[i]);
//this.add(new JButton(arg[i]));
this.add(b);
if(i==0||i==1||i==2||i==4||i==5||i==6||i==8||i==9||i==10||i==12)
{
b.addActionListener(new ActionListener()
{
public void actionPerformed(ActionEvent e)
{
String mark=b.getText();
String ma=text.getText();
if(vc3.contains("v3"))
{
text.setText("0."+mark);
vc3.clear();
}
else if(vc.contains("a"))
{
if(vc2.contains("v2"))
{
text.setText("0."+mark);
vc.clear();
vc2.clear();
}
else
{
text.setText(mark);
vc.clear();
Vec.clear();
Vec.add(mark);
}
}
else
{
text.setText(ma.trim()+mark);
Vec.add(mark);
}
begin="no";
to="yes";
}
});
}
if(i==14)
{
b.addActionListener(new ActionListener()
{
public void actionPerformed(ActionEvent e)
{
String mar=b.getText();
String m=text.getText();
if("yes".equals(begin))
{
vc3.add("v3");
}
if(vc1.contains("v1"))
{
vc2.add("v2");
vc1.clear();
}
if(!Vec.contains(".")&&!vc.contains("a"))
{
text.setText(m.trim()+mar);
Vec.add(".");
}
}
});
}
if(i==15)
{
b.addActionListener(new ActionListener()
{
public void actionPerformed(ActionEvent e)
{
String ma=text.getText();
add=Double.parseDouble(ma);
if(what==null)
{
tool=add;
what="add";
}
else
{
tool=tool+add;
text.setText(String.valueOf((tool)));
}
vc.add("a");
vc1.add("v1");
to="+";
}
});
}
if(i==11)
{
b.addActionListener(new ActionListener()
{
public void actionPerformed(ActionEvent e)
{
String ma=text.getText();
jq=Double.parseDouble(ma);
if(what==null)
{
tool=jq;
what="jq";
}
else
{
tool=tool-jq;
text.setText(String.valueOf((tool)));
}
vc.add("a");
vc1.add("v1");
to="-";
}
});
}
if(i==3)
{
b.addActionListener(new ActionListener()
{
public void actionPerformed(ActionEvent e)
{
String ma=text.getText();
cq=Double.parseDouble(ma);
if(what==null)
{
tool=cq;
what="cq";
}
else
{
tool=tool/cq;
text.setText(String.valueOf((tool)));
}
vc.add("a");
vc1.add("v1");
to="/";
}
});
}
if(i==7)
{
b.addActionListener(new ActionListener()
{
public void actionPerformed(ActionEvent e)
{
String ma=text.getText();
cs=Double.parseDouble(ma);
if(what==null)
{
tool=cs;
what="cs";
}
else
{
tool=tool*cs;
text.setText(String.valueOf((tool)));
}
vc.add("a");
vc1.add("v1");
to="*";
}
});
}
if(i==13)
{
b.addActionListener(new ActionListener()
{
public void actionPerformed(ActionEvent e)
{
String ma=text.getText();
dy=Double.parseDouble(ma);
if(what=="add")
{
jg=String.valueOf((tool+dy));
}
if(what=="jq")
{
jg=String.valueOf((tool-dy));
}
if(what=="cs")
{
jg=String.valueOf((tool*dy));
}
if(what=="cq")
{
jg=String.valueOf((tool/dy));
}
if(what==null)
{
if(to=="+")
{
tool=add;
jg=String.valueOf(tool+dy);
}
else if(to=="-")
{
tool=jq;
jg=String.valueOf(dy-tool);
}
else if(to=="*")
{
tool=cs;
jg=String.valueOf(dy*tool);
}
else if(to=="/")
{
tool=cq;
jg=String.valueOf(dy/tool);
}
else
{
jg=String.valueOf(dy);
}
}
text.setText(jg);
Vec.clear();
Vec.add(".");
vc.add("a");
vc1.add("v1");
what=null;
tool=0;
}
});
}
}
}
}
class Centernorth extends JPanel {
public Centernorth() {
final JTextField text=Tool.getinstance().getfield();
}
}
class Centerpanel extends JPanel {
public Centerpanel() {
this.setLayout(new BorderLayout(8,7));
Centernorth cn=new Centernorth();
Centercenter cc=new Centercenter();
Centerwest cw=new Centerwest();
this.add(cn,BorderLayout.NORTH);
this.add(cc,BorderLayout.CENTER);
this.add(cw,BorderLayout.WEST);
}
}
class Centerwest extends JPanel {
public Centerwest() {
}
}
class Northpanel extends JPanel {
private JTextField tf;
public Northpanel() {
tf=Tool.getinstance().getfield();
this.add(tf);
}
}
------------------------------------------------------------
才子_辉祝您愉快！
Ⅲ java怎样写一个简单的计算器
以下是一个简单的例子，这个计算器可以执行加、减、乘、除操作：
import java.util.Scanner;
public class Calculator {
public static void main(String[] args) {
Scanner scanner = new Scanner(System.in);
System.out.println("Enter first number:");
double num1 = scanner.nextDouble();
System.out.println("Enter second number:");
double num2 = scanner.nextDouble();
System.out.println("Enter an operator (+, -, *, /):");
char operator = scanner.next().charAt(0);
scanner.close();
double output;
switch(operator)
{
case '+':
output = num1 + num2;
break;
case '-':
output = num1 - num2;
break;
case '*':
output = num1 * num2;
break;
case '/':
if (num2 != 0) {
output = num1 / num2;
} else {
System.out.println("Error! Dividing by zero is not allowed.");
return;
}
break;
default:
System.out.println("Error! Invalid operator. Only +, -, * and / are allowed.");
return;
}
System.out.println("The result is given as follows:");
System.out.printf("%.1f %c %.1f = %.1f\n", num1, operator, num2, output);
}
}
在这个程序中，我们首先使用Scanner类从用户那里获取两个数字和一个运算符。然后，我们使用switch语句根据运算符执行相应的数学运算。最后，我们输出结果。
Ⅳ 求简单java写计算器代码加减乘除
import javax.swing.*;
import java.awt.*;
import java.awt.event.*;
public class Calculator extends JFrame implements ActionListener
{
private boolean dotExist, operated, equaled; // 帮助运算的布尔变量
private double storedNumber; // 目前的结果
private char lastOperator; // 表示上一运算符
private JTextField operation; // 结果栏
private JButton dot, plus, minus, multi, div, sqrt, equal, changePN, clear; // 运算符
private JButton[] numbers; // 数字
// 构造者
public Calculator()
{
setTitle("Calculator");
// 初始化变量
dotExist = false; // 表示当前的数是否有小数点
operated = false; // 表示任意运算符是否被按下
equaled = false; // 表示等号是否被按下
storedNumber = 0;
lastOperator = '?';
// 初始化窗口变量
operation = new JTextField("0");
operation.setEditable(false);
numbers = new JButton[10];
for (int i = 0; i < 10; i++)
numbers[i] = new JButton("" + i);
dot = new JButton(".");
plus = new JButton("+");
minus = new JButton("-");
multi = new JButton("*");
div = new JButton("/");
sqrt = new JButton("√");
equal = new JButton("=");
changePN = new JButton("±");
clear = new JButton("AC");
// 将窗口物体放入窗口
GridBagLayout layout = new GridBagLayout();
getContentPane().setLayout(layout);
addComponent(layout, operation, 0, 0, 4, 1);
addComponent(layout, numbers[1], 1, 0, 1, 1);
addComponent(layout, numbers[2], 1, 1, 1, 1);
addComponent(layout, numbers[3], 1, 2, 1, 1);
addComponent(layout, numbers[4], 2, 0, 1, 1);
addComponent(layout, numbers[5], 2, 1, 1, 1);
addComponent(layout, numbers[6], 2, 2, 1, 1);
addComponent(layout, numbers[7], 3, 0, 1, 1);
addComponent(layout, numbers[8], 3, 1, 1, 1);
addComponent(layout, numbers[9], 3, 2, 1, 1);
addComponent(layout, dot, 4, 0, 1, 1);
addComponent(layout, numbers[0], 4, 1, 1, 1);
addComponent(layout, sqrt, 4, 2, 1, 1);
addComponent(layout, plus, 1, 3, 1, 1);
addComponent(layout, minus, 2, 3, 1, 1);
addComponent(layout, multi, 3, 3, 1, 1);
addComponent(layout, div, 4, 3, 1, 1);
addComponent(layout, equal, 5, 0, 2, 1);
addComponent(layout, changePN, 5, 2, 1, 1);
addComponent(layout, clear, 5, 3, 1, 1);
}
// 对按钮进行反应的方法
public void actionPerformed(ActionEvent e)
{
JButton btn = (JButton)e.getSource();
if (btn == clear)
{
operation.setText("0");
dotExist = false;
storedNumber = 0;
lastOperator = '?';
}
else if (btn == equal)
{
operate('=');
equaled = true;
}
else if (btn == plus)
{
operate('+');
equaled = false;
}
else if (btn == minus)
{
operate('-');
equaled = false;
}
else if (btn == multi)
{
operate('*');
equaled = false;
}
else if (btn == div)
{
operate('/');
equaled = false;
}
else if (btn == changePN)
{
operate('p');
operate('=');
equaled = true;
}
else if (btn == sqrt)
{
operate('s');
operate('=');
equaled = true;
}
else
{
if (equaled)
storedNumber = 0;
for (int i = 0; i < 10; i++)
if (btn == numbers[i])
{
if (operation.getText().equals("0"))
operation.setText("" + i);
else if(! operated)
operation.setText(operation.getText() + i);
else
{
operation.setText("" + i);
operated = false;
}
}
if (btn == dot && ! dotExist)
{
operation.setText(operation.getText() + ".");
dotExist = true;
}
}
}
// 进行运算的方法
private void operate(char operator)
{
double currentNumber = Double.valueOf(operation.getText()).doubleValue();
if (lastOperator == '?')
storedNumber = currentNumber;
else if (lastOperator == '+')
storedNumber += currentNumber;
else if (lastOperator == '-')
storedNumber -= currentNumber;
else if (lastOperator == '*')
storedNumber *= currentNumber;
else if (lastOperator == '/')
storedNumber /= currentNumber;
else if (lastOperator == 'p')
storedNumber *= -1;
else if (lastOperator == 's')
storedNumber = Math.sqrt(currentNumber);
else if (lastOperator == '=' && equaled)
storedNumber = currentNumber;
operation.setText("" + storedNumber);
operated = true;
lastOperator = operator;
}
// 快捷使用GridBagLayout的方法
private void addComponent(GridBagLayout layout, Component component, int row, int col, int width, int height)
{
GridBagConstraints constraints = new GridBagConstraints();
constraints.fill = GridBagConstraints.BOTH;
constraints.insets = new Insets(10, 2, 10, 2);
constraints.weightx = 100;
constraints.weighty = 100;
constraints.gridx = col;
constraints.gridy = row;
constraints.gridwidth = width;
constraints.gridheight = height;
layout.setConstraints(component, constraints);
if (component instanceof JButton)
((JButton)component).addActionListener(this);
getContentPane().add(component);
}
// 主方法初始化并显示窗口
public static void main(String[] args)
{
Calculator calc = new Calculator();
calc.setSize(290, 400);
calc.setVisible(true);
}
}