Java GUI做简易计算器
貌似逻辑有点问题，界面还能用，凑合着看吧。。有空再改。。
package calculator;
/*公共类：calculator
功能：计算器界面
版本：1.0 Bill 2015 11 28
实现了计算器界面布置，准备加入事件
2.0 Bill 2015 12 2
计划加入监听事件，实现按键功能
2.1 Bill 2015 12 5
打算关闭再打开时能显示上次的结果,结果失败，逻辑上出现问题
*/
import java.awt.*; //绘制组件
import java.awt.event.*; //监听事件组件
import javax.swing.*; //gui组件
import java.io.*; //用于存储和恢复文件的包
public class calculator //implements ActionListener
implements ActionListener
{
JFrame frame;
JButton btn[]=new JButton[12]; //12个用来放数字
JButton add,minus,plus,divide,clean,back,sqrt,equal; //分别是+，-，*，/，全清，删除，开方，等于
double x,y; //计算的数字
int z; //用来存储符号
int z2;
JTextField field;
StringBuffer str;
public static void main(String[] args)
{
calculator cal=new calculator();
}
public calculator()
{
frame=new JFrame("我的第一个计算器");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); //关闭gui时关程序
frame.getContentPane(); //获得面板内容
JPanel shangBufen=new JPanel(); //上半部分的面板
JPanel xiaBufen=new JPanel(); //下半部分的面板
//创建一个空字符串缓冲区
str=new StringBuffer();
//下面编辑上半部分的面板
field=new JTextField(30); //20字宽的文本框用于显示(可能要改一下显示字体大小)
field.setText("0");
field.setHorizontalAlignment(JTextField.RIGHT); //文本对齐右边
field.setEditable(false);
shangBufen.add(field);
shangBufen.setLayout(new GridLayout(2,1)); //两行一列
//0~9数字的实例化
String s;
for(int i=0;i<10;i++)
{
s=""+i;
btn[i]=new JButton(s);
btn[i].addActionListener(this);
}
btn[10]=new JButton("-/+");
btn[10].addActionListener(this);
btn[11]=new JButton(".");
btn[11].addActionListener(this);
add=new JButton("+");minus=new JButton("-");
add.addActionListener(this);minus.addActionListener(this);
plus=new JButton("*");divide=new JButton("/");
plus.addActionListener(this);divide.addActionListener(this);
clean=new JButton("C");back=new JButton("Back");
clean.addActionListener(this);back.addActionListener(this);
sqrt=new JButton("Sqrt");equal=new JButton("=");
sqrt.addActionListener(this);equal.addActionListener(this);
xiaBufen.add(btn[7]); xiaBufen.add(btn[8]); xiaBufen.add(btn[9]); xiaBufen.add(add); xiaBufen.add(minus);
xiaBufen.add(btn[4]); xiaBufen.add(btn[5]); xiaBufen.add(btn[6]); xiaBufen.add(plus); xiaBufen.add(divide);
xiaBufen.add(btn[1]); xiaBufen.add(btn[2]);xiaBufen.add(btn[3]); xiaBufen.add(clean); xiaBufen.add(back);
xiaBufen.add(btn[0]); xiaBufen.add(btn[10]); xiaBufen.add(btn[11]);xiaBufen.add(sqrt);xiaBufen.add(equal);
xiaBufen.setLayout(new GridLayout(4,5,5,5)); //四行五列，间隔5像素
frame.add(shangBufen);
frame.add(xiaBufen);
frame.setLayout(new FlowLayout()); //顺序排列
frame.setSize(400,300);
frame.setResizable(false); //禁止修改窗口大小
frame.setVisible(true);
}
public void actionPerformed(ActionEvent event) //监听事件的实现
{
try
{
if(event.getSource()==clean) //清除显示的按键
{
field.setText("0"); //清零显示
field.setHorizontalAlignment(JTextField.RIGHT); //文本对齐右边
str.setLength(0); //字符串缓冲区清零
z=0;z2=0;
}
else if(event.getSource()==back) //清除一个字符的按键
{
if(!field.getText().trim().equals("0")) //如果显示的不是0,trim()是提取消除空格之后的字符串
{
if(str.length()!=1)
{
field.setText(str.delete(str.length()-1,str.length()).toString());//清除最后一个字符,可能抛出字符串越界异常
field.setHorizontalAlignment(JTextField.RIGHT);
}
else
{
field.setText("0");
field.setHorizontalAlignment(JTextField.RIGHT);
str.setLength(0);
}
}
}
else if(event.getSource()==btn[10]) //取反的按键
{
x=Double.parseDouble(field.getText().trim());
x=-x;
field.setText(""+x);
field.setHorizontalAlignment(JTextField.RIGHT);
}
else if(event.getSource()==btn[11]) //小数点的按钮
{
//首先判断字符串中是否包含小数点了
if(field.getText().trim().indexOf(".")==-1) //没有找到就返回-1
{
field.setText(str.append(event.getActionCommand()).toString()); //getActionCommmand()是返回发生事件的对象
field.setHorizontalAlignment(JTextField.RIGHT);
}
}else if(event.getSource()==sqrt) //求平方根的按键
{
x=Double.parseDouble(field.getText().trim());
if(x>=0)
{
x=Math.sqrt(x);
field.setText(""+x);
field.setHorizontalAlignment(JTextField.RIGHT);
}
y=0d;
str.setLength(0);
str.append(""+x);
}else if(event.getSource()==add) //"+"的按键
{
if(z!=0)
{
y=Double.parseDouble(field.getText().trim());
str.setLength(0);
switch(z)
{case 1:field.setText(str.append(""+(x+y)).toString());field.setHorizontalAlignment(JTextField.RIGHT);break;
case 2:field.setText(str.append(""+(x+y)).toString());field.setHorizontalAlignment(JTextField.RIGHT);break;
case 3:field.setText(str.append(""+(x+y)).toString());field.setHorizontalAlignment(JTextField.RIGHT);break;
case 4:field.setText(str.append(""+(x+y)).toString());field.setHorizontalAlignment(JTextField.RIGHT);break;
case 0:break;
}
}else
{field.setText(""+0);}
y=0d;
z=1;z2=1;
}else if(event.getSource()==minus) //“-”的按键
{
if(z!=0)
{
y=Double.parseDouble(field.getText().trim());
str.setLength(0);
switch(z)
{case 1:field.setText(str.append(""+(x+y)).toString());field.setHorizontalAlignment(JTextField.RIGHT);break;
case 2:field.setText(str.append(""+(x+y)).toString());field.setHorizontalAlignment(JTextField.RIGHT);break;
case 3:field.setText(str.append(""+(x+y)).toString());field.setHorizontalAlignment(JTextField.RIGHT);break;
case 4:field.setText(str.append(""+(x+y)).toString());field.setHorizontalAlignment(JTextField.RIGHT);break;
case 0:break;
}
}else
{field.setText(""+0);}
y=0d;
z=2;z2=1;
}else if(event.getSource()==plus) //“*”的按键
{
if(z!=0)
{
y=Double.parseDouble(field.getText().trim());
str.setLength(0);
switch(z)
{case 1:field.setText(str.append(""+(x+y)).toString());field.setHorizontalAlignment(JTextField.RIGHT);break;
case 2:field.setText(str.append(""+(x+y)).toString());field.setHorizontalAlignment(JTextField.RIGHT);break;
case 3:field.setText(str.append(""+(x+y)).toString());field.setHorizontalAlignment(JTextField.RIGHT);break;
case 4:field.setText(str.append(""+(x+y)).toString());field.setHorizontalAlignment(JTextField.RIGHT);break;
case 0:break;
}
}else
{field.setText(""+0);}
y=0d;
z=3;z2=1;
}else if(event.getSource()==divide) //“/”的按键
{
if(z!=0)
{
y=Double.parseDouble(field.getText().trim());
str.setLength(0);
switch(z)
{case 1:field.setText(str.append(""+(x+y)).toString());field.setHorizontalAlignment(JTextField.RIGHT);break;
case 2:field.setText(str.append(""+(x+y)).toString());field.setHorizontalAlignment(JTextField.RIGHT);break;
case 3:field.setText(str.append(""+(x+y)).toString());field.setHorizontalAlignment(JTextField.RIGHT);break;
case 4:field.setText(str.append(""+(x+y)).toString());field.setHorizontalAlignment(JTextField.RIGHT);break;
case 0:break;
}
}else
{field.setText(""+0);}
y=0d;
z=4;z2=1;
}else if(event.getSource()==equal)
{
y=Double.parseDouble(field.getText().trim());
str.setLength(0);
switch(z)
{case 1:field.setText(str.append(""+(x+y)).toString());field.setHorizontalAlignment(JTextField.RIGHT);break;
case 2:field.setText(str.append(""+(x+y)).toString());field.setHorizontalAlignment(JTextField.RIGHT);break;
case 3:field.setText(str.append(""+(x+y)).toString());field.setHorizontalAlignment(JTextField.RIGHT);break;
case 4:field.setText(str.append(""+(x+y)).toString());field.setHorizontalAlignment(JTextField.RIGHT);break;
case 0:break;
}
z=0;z2=0;
}else if(event.getSource()==btn[0])
{
if(!field.getText().trim().equals("0"))
{
field.setText(str.append(event.getActionCommand()).toString()); //getActionCommmand()是返回发生事件的对象
field.setHorizontalAlignment(JTextField.RIGHT);
}
}else //输入的是其他数字
{ if(z!=0)
{
if(z2==1)
{
str.setLength(0);
field.setText(str.append(event.getActionCommand()).toString()); //getActionCommmand()是返回发生事件的对象
field.setHorizontalAlignment(JTextField.RIGHT);
x=Double.parseDouble(field.getText().trim());
z2=0;
}else
{
field.setText(str.append(event.getActionCommand()).toString()); //getActionCommmand()是返回发生事件的对象
field.setHorizontalAlignment(JTextField.RIGHT);
x=Double.parseDouble(field.getText().trim());
}
}else
{
field.setText(str.append(event.getActionCommand()).toString()); //getActionCommmand()是返回发生事件的对象
field.setHorizontalAlignment(JTextField.RIGHT);
x=Double.parseDouble(field.getText().trim());
}
}
}catch(NumberFormatException e1) //异常处理
{e1.printStackTrace();}
catch(StringIndexOutOfBoundsException e2) //字符串索引超出范围
{e2.printStackTrace();}
}
}