JAVA实现简单计算器布局与功能（附完整源码）
初识java：利用swing制作一个简单的计算器
涉及学习内容：
- 设置窗口
- 设置按键
- 设置文本框只读
- String字符串操作：与double类型间的相互转换
- 设置字体属性
- 对计算器多种使用情况的考虑，如以加减法为例：
- 正常操作，输入一个数后按+号再按另一个数字：12+15
- 考虑使用者先按+号，那么应该该显示：0+，乘除则为1*；
- 被除数不能为0。
本计算器不足之处：
1、除的计算结果保留15位数
2、定义double类型计算能力有限
3、文本框长度不足
代码较长，仅供参考，初学Java，如有不足之处请多多指教。
设置框架、按钮与文本框：
public void iniFrame() {
setTitle("My Number Computer");
setDefaultCloseOperation(EXIT_ON_CLOSE);
setSize(400, 660);
setLocation(500,150);
}
public void iniButton() {
JButton b_dot=new JButton(".");
JButton b_equ=new JButton("=");
JButton b_div=new JButton("/");
JButton b_mul=new JButton("*");
JButton b_sub=new JButton("-");
JButton b_plu=new JButton("+");
JButton b_0=new JButton("0");
JButton b_1=new JButton("1");
JButton b_2=new JButton("2");
JButton b_3=new JButton("3");
JButton b_4=new JButton("4");
JButton b_5=new JButton("5");
JButton b_6=new JButton("6");
JButton b_7=new JButton("7");
JButton b_8=new JButton("8");
JButton b_9=new JButton("9");
pan_button.add(b_7);
pan_button.add(b_8);
pan_button.add(b_9);
pan_button.add(b_div);
pan_button.add(b_4);
pan_button.add(b_5);
pan_button.add(b_6);
pan_button.add(b_mul);
pan_button.add(b_1);
pan_button.add(b_2);
pan_button.add(b_3);
pan_button.add(b_sub);
pan_button.add(b_dot);
pan_button.add(b_0);
pan_button.add(b_equ);
pan_button.add(b_plu);
pan_button.setBackground(Color.BLACK);
pan_button.setLayout(new GridLayout(4,4,1,1));
pan_button.setSize(398,358);
b_dot.addActionListener(new B_dot());
b_equ.addActionListener(new B_equ());
b_div.addActionListener(new B_div());
b_mul.addActionListener(new B_mul());
b_sub.addActionListener(new B_sub());
b_plu.addActionListener(new B_plu());
b_0.addActionListener(new B_0());
b_1.addActionListener(new B_1());
b_2.addActionListener(new B_2());
b_3.addActionListener(new B_3());
b_4.addActionListener(new B_4());
b_5.addActionListener(new B_5());
b_6.addActionListener(new B_6());
b_7.addActionListener(new B_7());
b_8.addActionListener(new B_8());
b_9.addActionListener(new B_9());
}
public void iniTextField() {对应按键类以及判定类：
public class judge{
public void jdg(char a) {
if(a==0)//表示没有按运算键
if(num.length()==0)
result=0;//而且没有输入值，如直接按等于号，
else
result=Double.parseDouble(num);//有输入值按等于号
else
//考虑sign=加减乘除的四种情况，b作为计算结果显示在下面的文本框
switch (a) {
case '+':
result += Double.parseDouble(num);
break;
case '-':
result -= Double.parseDouble(num);
break;
case '*':
result *= Double.parseDouble(num);
break;
case '/':
double aa;
aa= Double.parseDouble(num);
if(aa==0) {
ta_num1.setText("除数不能为0");
num="";
str1="";
result=0;
break;
}
result = result/aa;
break;
}
ta_num1.setText(String.valueOf(result));
}
}
public class B_dot implements ActionListener {
public void actionPerformed(ActionEvent e) {
num+=".";
ta_num.setText(num);
}
}
public class B_equ extends judge implements ActionListener {
public void actionPerformed(ActionEvent e) {
int r;
r=str1.length();
if(r>0&&num.length()==0)
{
char a[]=str1.toCharArray();
if(a[r-1]<48||a[r-1]>57)
{
ta_num.setText("0");
ta_num1.setText(String.valueOf(result));
return;
}
}
this.jdg(sign);
ta_num.setText(String.valueOf(result));
str1="";
num=String.valueOf(result);
sign='=';
}//等于号之后全部归0，返回初始状态
}
public class B_div extends judge implements ActionListener {
public void actionPerformed(ActionEvent e) {
int r;
r=str1.length();
if(r>0&&num.length()==0)//str1不为空，num为空
{
char a[]=str1.toCharArray();
if(a[r-1]<48||a[r-1]>57)//acsii码；判断最后一个是不是运算符
{
a[str1.length()-1]=47;
str1=String.valueOf(a);
ta_num.setText(str1);
sign='/';//是的话就变成除号/
return;
}
}
if(num.length()==0)//下空
{
str1=new String("0");
ta_num.setText("0");
}//初始状态按÷，
str1+=num+new String("÷"); //把num和运算符号加在str1后面
ta_num.setText(str1);
this.jdg(sign);//执行上一个运算符；
sign='/';
ta_num.setText(str1);
num="";//这时num没用了，就置空方便下次输入
}
}
public class B_mul extends judge implements ActionListener {
public void actionPerformed(ActionEvent e) {
int r;
r=str1.length();
if(r>0&&num.length()==0)
{
char a[]=str1.toCharArray();
if(a[r-1]<48||a[r-1]>57)
{
a[str1.length()-1]=42;
str1=String.valueOf(a);
ta_num.setText(str1);
sign='*';
return;
}
}
if(num.length()==0)//下空
{
str1=new String("1");
ta_num1.setText("0");
result=1;
}//初始状态按*，
str1+=num+new String("*");
ta_num.setText(str1);
this.jdg(sign);//执行上一个运算符；
sign='*';
ta_num.setText(str1);
num="";
}
}
public class B_sub extends judge implements ActionListener {
public void actionPerformed(ActionEvent e) {
int r;
r=str1.length();
if(r>0&&num.length()==0)
{
char a[]=str1.toCharArray();
if(a[r-1]<48||a[r-1]>57)
{
a[str1.length()-1]=45;
str1=String.valueOf(a);
ta_num.setText(str1);
sign='-';
return;
}
}
if(num.length()==0)//下空
{
str1=new String("0");
ta_num1.setText("0");
}//初始状态按-，
str1+=num+new String("-");
ta_num.setText(str1);
this.jdg(sign);//执行上一个运算符；
sign='-';
ta_num.setText(str1);
num="";
}
}
public class B_plu extends judge implements ActionListener {对应数字类：
public class B_0 implements ActionListener {
public void actionPerformed(ActionEvent e) {
num+=0;
ta_num.setText(str1+num);
}
}
public class B_1 implements ActionListener {
public void actionPerformed(ActionEvent e) {
num+=1;
ta_num.setText(str1+num);
}
}
public class B_2 implements ActionListener {
public void actionPerformed(ActionEvent e) {
num+=2;
ta_num.setText(str1+num);
}
}
public class B_3 implements ActionListener {
public void actionPerformed(ActionEvent e) {
num+=3;
ta_num.setText(str1+num);
}
}
public class B_4 implements ActionListener {
public void actionPerformed(ActionEvent e) {
num+=4;
ta_num.setText(str1+num);
}
}
public class B_5 implements ActionListener {
public void actionPerformed(ActionEvent e) {
num+=5;
ta_num.setText(str1+num);
}
}
public class B_6 implements ActionListener {
public void actionPerformed(ActionEvent e) {
num+=6;
ta_num.setText(str1+num);
}
}
public class B_7 implements ActionListener {
public void actionPerformed(ActionEvent e) {
num+=7;
ta_num.setText(str1+num);
}
}
public class B_8 implements ActionListener {
public void actionPerformed(ActionEvent e) {
num+=8;
ta_num.setText(str1+num);
}
}
public class B_9 implements ActionListener {源代码如下：
package elevenWeek;
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
public class NumComputer extends JFrame implements ActionListener{
/**
* serializable 类 NumComputer 未声明类型为 long 的静态终态 serialVersionUID 字段
*/
private static final long serialVersionUID = 9220237278254619785L;
JPanel pan_button = new JPanel();
JPanel pan_textfield = new JPanel();
String num="";
String str1=""; //存储所有点击按键的结果显示于上面的文本框
double result=0;
char sign=0;
public JTextArea ta_num=new JTextArea(2,36);
public JTextArea ta_num1=new JTextArea(1,36);
public NumComputer() {
iniFrame();
iniButton();
iniTextField();
Container con = getContentPane();
con.setLayout(null);
con.add(pan_textfield);
con.add(pan_button);
con.setLayout(new GridLayout(2,1));
setVisible(true);
}
public void iniFrame() {
setTitle("My Number Computer");
setDefaultCloseOperation(EXIT_ON_CLOSE);
setSize(400, 660);
setLocation(500,150);
}
public void iniButton() {
JButton b_dot=new JButton(".");
JButton b_equ=new JButton("=");
JButton b_div=new JButton("/");
JButton b_mul=new JButton("*");
JButton b_sub=new JButton("-");
JButton b_plu=new JButton("+");
JButton b_0=new JButton("0");
JButton b_1=new JButton("1");
JButton b_2=new JButton("2");
JButton b_3=new JButton("3");
JButton b_4=new JButton("4");
JButton b_5=new JButton("5");
JButton b_6=new JButton("6");
JButton b_7=new JButton("7");
JButton b_8=new JButton("8");
JButton b_9=new JButton("9");
pan_button.add(b_7);
pan_button.add(b_8);
pan_button.add(b_9);
pan_button.add(b_div);
pan_button.add(b_4);
pan_button.add(b_5);
pan_button.add(b_6);
pan_button.add(b_mul);
pan_button.add(b_1);
pan_button.add(b_2);
pan_button.add(b_3);
pan_button.add(b_sub);
pan_button.add(b_dot);
pan_button.add(b_0);
pan_button.add(b_equ);
pan_button.add(b_plu);
pan_button.setBackground(Color.BLACK);
pan_button.setLayout(new GridLayout(4,4,1,1));
pan_button.setSize(398,358);
b_dot.addActionListener(new B_dot());
b_equ.addActionListener(new B_equ());
b_div.addActionListener(new B_div());
b_mul.addActionListener(new B_mul());
b_sub.addActionListener(new B_sub());
b_plu.addActionListener(new B_plu());
b_0.addActionListener(new B_0());
b_1.addActionListener(new B_1());
b_2.addActionListener(new B_2());
b_3.addActionListener(new B_3());
b_4.addActionListener(new B_4());
b_5.addActionListener(new B_5());
b_6.addActionListener(new B_6());
b_7.addActionListener(new B_7());
b_8.addActionListener(new B_8());
b_9.addActionListener(new B_9());
}
public void iniTextField() {
pan_textfield.add(ta_num);
pan_textfield.add(ta_num1);
pan_textfield.setSize(398,298);
ta_num.setFont(new java.awt.Font("宋体", Font.BOLD, 18));
ta_num.setEnabled(false); //只读
ta_num.setText("请输入：");//显示内容
ta_num1.setFont(new java.awt.Font("宋体", Font.BOLD, 18));
ta_num1.setEnabled(false); //只读
ta_num1.setText("0");//显示内容
}
@Override
public void actionPerformed(ActionEvent e) {
// TODO 自动生成的方法存根
}
public class judge{
public void jdg(char a) {
if(a==0)//表示没有按运算键
if(num.length()==0)
result=0;//而且没有输入值，如直接按等于号，
else
result=Double.parseDouble(num);//有输入值按等于号
else
//考虑sign=加减乘除的四种情况，b作为计算结果显示在下面的文本框
switch (a) {
case '+':
result += Double.parseDouble(num);
break;
case '-':
result -= Double.parseDouble(num);
break;
case '*':
result *= Double.parseDouble(num);
break;
case '/':
double aa;
aa= Double.parseDouble(num);
if(aa==0) {
ta_num1.setText("除数不能为0");
num="";
str1="";
result=0;
break;
}
result = result/aa;
break;
}
ta_num1.setText(String.valueOf(result));
}
}
public class B_dot implements ActionListener {
public void actionPerformed(ActionEvent e) {
num+=".";
ta_num.setText(num);
}
}
public class B_equ extends judge implements ActionListener {
public void actionPerformed(ActionEvent e) {
int r;
r=str1.length();
if(r>0&&num.length()==0)
{
char a[]=str1.toCharArray();
if(a[r-1]<48||a[r-1]>57)
{
ta_num.setText("0");
ta_num1.setText(String.valueOf(result));
return;
}
}
this.jdg(sign);
ta_num.setText(String.valueOf(result));
str1="";
num=String.valueOf(result);
sign='=';
}//等于号之后全部归0，返回初始状态
}
public class B_div extends judge implements ActionListener {
public void actionPerformed(ActionEvent e) {
int r;
r=str1.length();
if(r>0&&num.length()==0)//str1不为空，num为空
{
char a[]=str1.toCharArray();
if(a[r-1]<48||a[r-1]>57)//acsii码；判断最后一个是不是运算符
{
a[str1.length()-1]=47;
str1=String.valueOf(a);
ta_num.setText(str1);
sign='/';//是的话就变成除号/
return;
}
}
if(num.length()==0)//下空
{
str1=new String("0");
ta_num.setText("0");
}//初始状态按÷，
str1+=num+new String("÷"); //把num和运算符号加在str1后面
ta_num.setText(str1);
this.jdg(sign);//执行上一个运算符；
sign='/';
ta_num.setText(str1);
num="";//这时num没用了，就置空方便下次输入
}
}
public class B_mul extends judge implements ActionListener {
public void actionPerformed(ActionEvent e) {
int r;
r=str1.length();
if(r>0&&num.length()==0)
{
char a[]=str1.toCharArray();
if(a[r-1]<48||a[r-1]>57)
{
a[str1.length()-1]=42;
str1=String.valueOf(a);
ta_num.setText(str1);
sign='*';
return;
}
}
if(num.length()==0)//下空
{
str1=new String("1");
ta_num1.setText("0");
result=1;
}//初始状态按*，
str1+=num+new String("*");
ta_num.setText(str1);
this.jdg(sign);//执行上一个运算符；
sign='*';
ta_num.setText(str1);
num="";
}
}
public class B_sub extends judge implements ActionListener {
public void actionPerformed(ActionEvent e) {
int r;
r=str1.length();
if(r>0&&num.length()==0)
{
char a[]=str1.toCharArray();
if(a[r-1]<48||a[r-1]>57)
{
a[str1.length()-1]=45;
str1=String.valueOf(a);
ta_num.setText(str1);
sign='-';
return;
}
}
if(num.length()==0)//下空
{
str1=new String("0");
ta_num1.setText("0");
}//初始状态按-，
str1+=num+new String("-");
ta_num.setText(str1);
this.jdg(sign);//执行上一个运算符；
sign='-';
ta_num.setText(str1);
num="";
}
}
public class B_plu extends judge implements ActionListener {
public void actionPerformed(ActionEvent e) {
int r;
r=str1.length();
if(r>0&&num.length()==0)
{
char a[]=str1.toCharArray();
if(a[r-1]<48||a[r-1]>57)
{
a[str1.length()-1]=43;
str1=String.valueOf(a);
ta_num.setText(str1);
sign='+';
return;
}
}//对连续出现两个运算符号进行操作
if(num.length()==0)//下空
{
str1=new String("0");
ta_num1.setText("0");
}//初始状态按+，
str1+=num+new String("+");
ta_num.setText(str1);
this.jdg(sign);//执行上一个运算符；
sign='+';
ta_num.setText(str1);
num="";
}
}
public class B_0 implements ActionListener {
public void actionPerformed(ActionEvent e) {
num+=0;
ta_num.setText(str1+num);
}
}
public class B_1 implements ActionListener {
public void actionPerformed(ActionEvent e) {
num+=1;
ta_num.setText(str1+num);
}
}
public class B_2 implements ActionListener {
public void actionPerformed(ActionEvent e) {
num+=2;
ta_num.setText(str1+num);
}
}
public class B_3 implements ActionListener {
public void actionPerformed(ActionEvent e) {
num+=3;
ta_num.setText(str1+num);
}
}
public class B_4 implements ActionListener {
public void actionPerformed(ActionEvent e) {
num+=4;
ta_num.setText(str1+num);
}
}
public class B_5 implements ActionListener {
public void actionPerformed(ActionEvent e) {
num+=5;
ta_num.setText(str1+num);
}
}
public class B_6 implements ActionListener {
public void actionPerformed(ActionEvent e) {
num+=6;
ta_num.setText(str1+num);
}
}
public class B_7 implements ActionListener {
public void actionPerformed(ActionEvent e) {
num+=7;
ta_num.setText(str1+num);
}
}
public class B_8 implements ActionListener {
public void actionPerformed(ActionEvent e) {
num+=8;
ta_num.setText(str1+num);
}
}
public class B_9 implements ActionListener {
public void actionPerformed(ActionEvent e) {
num+=9;
ta_num.setText(str1+num);
}
}
public static void main(String[] args)
{
@SuppressWarnings("unused")
NumComputer f = new NumComputer();
}
}