新手上路，怎样在JAVA程序中控制整数的数位？急！！！

[jf007945_2006]

想用JAVA作计算器，怎样在JAVA程序中控制整数的数位，有没有作计算器相关的程序借鉴一下。万分感谢！

[bovy]

能够说的更加具体一点么？怎么控制？

[King_Style]

整数先做运算再转成字符串就可以了

[PhoticX]

同意楼上 用计算器用字符串作

[nego_orange]

我以前练习的计算器程序希望对你能有帮助。


import javax.swing.*;
import java.awt.*;
import java.awt.event.*;

public class Calculator extends JFrame
{
JTextField jTextField1 = new JTextField("");
JMenuBar jMenuBar1 = new JMenuBar();
JPanel jPanel1 = new JPanel();
JButton jButton1=new JButton("7");
JButton jButton2=new JButton("8");
JButton jButton3=new JButton("9");
JButton jButton4=new JButton("/");
JButton jButton5=new JButton("sqrt");
JButton jButton6=new JButton("4");
JButton jButton7=new JButton("5");
JButton jButton8=new JButton("6");
JButton jButton9=new JButton("*");
JButton jButton10=new JButton("%");
JButton jButton11=new JButton("1");
JButton jButton12=new JButton("2");
JButton jButton13=new JButton("3");
JButton jButton14=new JButton("-");
JButton jButton15=new JButton("1/x");
JButton jButton16=new JButton("0");
JButton jButton17=new JButton("+/-");
JButton jButton18=new JButton(".");
JButton jButton19=new JButton("+");
JButton jButton20=new JButton("=");

JMenu jMenu1 = new JMenu();
JMenu jMenu2 = new JMenu();
JMenu jMenu3 = new JMenu();
JMenuItem jMenuItem1 = new JMenuItem();
JMenuItem jMenuItem2 = new JMenuItem();
JMenuItem jMenuItem3 = new JMenuItem();
JMenuItem jMenuItem4 = new JMenuItem();
JMenuItem jMenuItem5 = new JMenuItem();
JMenuItem jMenuItem6 = new JMenuItem();
JPanel jPanel2 = new JPanel();
FlowLayout flowLayout1 = new FlowLayout();
JButton jButtonB = new JButton();
JButton jButtonC = new JButton();
int CalcuType,CalcuType1;
double x,y;
String s="";
Double i;
boolean b=true;

public Calculator()
{
try
{
init();
}
catch(Exception e)
{
e.printStackTrace();
}
}
public void init()
{
this.getContentPane().setBackground(SystemColor.control);
jMenuBar1.setBackground(Color.lightGray);
jMenuBar1.setAlignmentX((float) 0.5);
jMenuBar1.setAlignmentY((float) 0.0);
jPanel1.setAlignmentY((float) 0.5);
jMenu1.setText("编辑（E）");
jMenu2.setText("查看（V）");
jMenu3.setText("帮助（H）");
jMenuItem1.setText("复制（C） Ctrl+C");
jMenuItem2.setText("粘贴（V） Ctrl+V");
jMenuItem3.setText("●标准型");
jMenuItem4.setText(" 数学型");
jMenuItem5.setText("帮助主题（H）");
jMenuItem6.setText("关于计算器（A）");
jTextField1.setText("");
jPanel2.setLayout(flowLayout1);
jButtonB.setText("BackSpace");
jButtonC.setText(" Clear ");
jButtonB.addActionListener(new ActionListener()
{
public void actionPerformed(ActionEvent e)
{
jTextField1.setText(jTextField1.getText().trim().substring
(0,jTextField1.getText().trim().length()-1));
}
});
jButtonC.addActionListener(new ActionListener()
{
public void actionPerformed(ActionEvent e)
{
jTextField1.setText("");
}
});
this.getContentPane().add(jTextField1, BorderLayout.NORTH);
this.getContentPane().add(jPanel2, BorderLayout.CENTER);
jPanel2.add(jButtonB, null);
jPanel2.add(jButtonC, null);
this.getContentPane().add(jPanel1, BorderLayout.SOUTH);

[nego_orange]

jPanel1.add(jButton1);
jPanel1.add(jButton2);
jPanel1.add(jButton3);
jPanel1.add(jButton4);
jPanel1.add(jButton5);
jPanel1.add(jButton6);
jPanel1.add(jButton7);
jPanel1.add(jButton8);
jPanel1.add(jButton9);
jPanel1.add(jButton10);
jPanel1.add(jButton11);
jPanel1.add(jButton12);
jPanel1.add(jButton13);
jPanel1.add(jButton14);
jPanel1.add(jButton15);
jPanel1.add(jButton16);
jPanel1.add(jButton17);
jPanel1.add(jButton18);
jPanel1.add(jButton19);
jPanel1.add(jButton20);

NumericListener a=new NumericListener();
jButton1.addActionListener(a);
jButton2.addActionListener(a);
jButton3.addActionListener(a);
jButton6.addActionListener(a);
jButton7.addActionListener(a);
jButton8.addActionListener(a);
jButton11.addActionListener(a);
jButton12.addActionListener(a);
jButton13.addActionListener(a);
jButton16.addActionListener(a);
jButton18.addActionListener(a);

OperationListener b=new OperationListener();
jButton4.addActionListener(b);
jButton5.addActionListener(b);
jButton9.addActionListener(b);
jButton10.addActionListener(b);
jButton14.addActionListener(b);
jButton15.addActionListener(b);
jButton19.addActionListener(b);

EqualsListener c=new EqualsListener();
jButton20.addActionListener(c);

SignsListener d=new SignsListener();
jButton17.addActionListener(d);

jPanel1.setLayout(new GridLayout(4,5));
jMenuBar1.add(jMenu1);
jMenuBar1.add(jMenu2);
jMenuBar1.add(jMenu3);
jMenu1.add(jMenuItem1);
jMenu1.add(jMenuItem2);
jMenu2.add(jMenuItem3);
jMenu2.add(jMenuItem4);
jMenu3.add(jMenuItem5);
jMenu3.add(jMenuItem6);
this.setJMenuBar(jMenuBar1);
}
class NumericListener implements ActionListener
{
public void actionPerformed(ActionEvent e)
{
jTextField1.setText(jTextField1.getText()+e.getActionCommand());
}
}
class OperationListener implements ActionListener
{
public void actionPerformed(ActionEvent e1)
{
if(jTextField1.getText().trim()!="")
{
if(e1.getActionCommand()=="1/x")
{
i=new Double(1/Double.valueOf(jTextField1.getText().trim()).doubleValue());
jTextField1.setText(i.toString());
}
else if(e1.getActionCommand()=="sqrt")
{
i=new Double(Math.sqrt(Double.valueOf(jTextField1.getText().trim()).doubleValue()));
jTextField1.setText(i.toString());
}
else if(e1.getActionCommand()=="+")
{
CalcuType=1;
CalcuType1=1;
x=Double.valueOf(jTextField1.getText().trim()).doubleValue();
jTextField1.setText("");
}
else if(e1.getActionCommand()=="-")
{
CalcuType=2;
CalcuType1=2;
x=Double.valueOf(jTextField1.getText().trim()).doubleValue();
jTextField1.setText("");
}
else if(e1.getActionCommand()=="*")
{
CalcuType=3;
CalcuType1=3;
x=Double.valueOf(jTextField1.getText().trim()).doubleValue();
jTextField1.setText("");
}
else if(e1.getActionCommand()=="/")
{
CalcuType=4;
CalcuType1=4;
x=Double.valueOf(jTextField1.getText().trim()).doubleValue();
jTextField1.setText("");
}
else if(e1.getActionCommand()=="%")
{
CalcuType=5;
x=Double.valueOf(jTextField1.getText().trim()).doubleValue();
jTextField1.setText("");
}
}
}
}
class EqualsListener implements ActionListener
{
public void actionPerformed(ActionEvent e)
{
y=Double.valueOf(jTextField1.getText().trim()).doubleValue();
if(CalcuType==1)
{
i=new Double(x+y);
jTextField1.setText(i.toString());
}
else if(CalcuType==2)
{
i=new Double(x-y);
jTextField1.setText(i.toString());
}
else if(CalcuType==3)
{
i=new Double(x*y);
jTextField1.setText(i.toString());
}
else if(CalcuType==4)
{
i=new Double(x/y);
jTextField1.setText(i.toString());
}
else if(CalcuType==5)
{
if(CalcuType1==1||CalcuType1==3)
{
i=new Double(x*y/100);
jTextField1.setText(i.toString());
}
else if(CalcuType1==2)
{
i=new Double(x-x*y/100);
jTextField1.setText(i.toString());
}
else if(CalcuType1==4)
{
i=new Double(x/y/100);
jTextField1.setText(i.toString());
}
}
}
}
class SignsListener implements ActionListener
{
public void actionPerformed(ActionEvent e)
{
b=!b;
if(b==false)
{
jTextField1.setText("-"+jTextField1.getText().trim());
}
}
}
public static void main(String[] args)
{
Calculator cal=new Calculator();
cal.setTitle("Java计算器");
cal.addWindowListener(new WindowAdapter()
{
public void windowClosing(WindowEvent e)
{
System.exit(0);
}
});
cal.pack();
cal.setVisible(true);
}
}

[shemalu]

UP~~~
帮顶一下`~~~

[十分钟年华老去]

读出来判断一下大小不就行了么或者就控制一下输入框输入字符的个数

[monly]

整数先做运算
再转成字符串
可参见上面几个程序

[littlebrid]

getActionCommand();
先区出文本框中的数字
setText()+getActionCommand();
"2"+"1"
21