下面文件名要为：JiSuanQi.java
import java.awt.*;
import java.awt.event.*;
public class JiSuanQi
{
String s="",s1=null,s2=null;
Frame f=new Frame("计算器");
TextField tf=new TextField(30);
Panel p1=new Panel();
Panel p2=new Panel();
Panel p3=new Panel();
Button bt1=new Button("=");
Button bt2=new Button("删除");
Button[] bt=new Button[16];
int id=0;
public static void main(String[] args)
{
new JiSuanQi().init();
}
public void init()
{
f.setBackground(new Color(85,247,253));
f.setLayout(new BorderLayout(4,4));
p2.setLayout(new GridLayout(4,4,4,4));
p3.setLayout(new BorderLayout(4,4));
f.setResizable(false);
f.add(p1,BorderLayout.NORTH);
f.add(p2);
p3.add(bt2,BorderLayout.NORTH);
p3.add(bt1);
p1.add(tf);
f.add(p3,BorderLayout.EAST);
String[] b={"1","2","3","+","4","5","6","-","7","8","9","*","0",".","复位","/"};
for(int i=0;i<16;i++)
{
bt[i]=new Button(b[i]);
p2.add(bt[i]);
}
bt[0].setForeground(Color.blue);
bt[1].setForeground(Color.blue);
bt[2].setForeground(Color.blue);
bt[4].setForeground(Color.blue);
bt[5].setForeground(Color.blue);
bt[6].setForeground(Color.blue);
bt[8].setForeground(Color.blue);
bt[9].setForeground(Color.blue);
bt[10].setForeground(Color.blue);
bt[12].setForeground(Color.blue);
bt[13].setForeground(Color.blue);
bt[3].setForeground(Color.red);
bt[7].setForeground(Color.red);
bt[11].setForeground(Color.red);
bt[15].setForeground(Color.red);
bt[14].setForeground(Color.red);
bt1.setForeground(Color.red);
bt2.setForeground(Color.red);
f.pack();
f.setVisible(true);
f.addWindowListener(new WindowAdapter()
{
public void windowClosing(WindowEvent e)
{
System.exit(0);
}
}
);
bt[0].addActionListener(new ActionListener()
{
public void actionPerformed(ActionEvent e)
{
s+=1;
s2+=1;
tf.setText(s);
}
}
);
bt[1].addActionListener(new ActionListener()
{
public void actionPerformed(ActionEvent e)
{
s+=2;
s2+=2;
tf.setText(s);
}
}
);
bt[2].addActionListener(new ActionListener()
{
public void actionPerformed(ActionEvent e)
{
s+=3;
s2+=3;
tf.setText(s);
}
}
);
bt[4].addActionListener(new ActionListener()
{
public void actionPerformed(ActionEvent e)
{
s+=4;
s2+=4;
tf.setText(s);
}
}
);
bt[5].addActionListener(new ActionListener()
{
public void actionPerformed(ActionEvent e)
{
s+=5;
s2+=5;
tf.setText(s);
}
}
);
bt[6].addActionListener(new ActionListener()
{
public void actionPerformed(ActionEvent e)
{
s+=6;
s2+=6;
tf.setText(s);
}
}
);
bt[8].addActionListener(new ActionListener()
{
public void actionPerformed(ActionEvent e)
{
s+=7;
s2+=7;
tf.setText(s);
}
}
);
bt[9].addActionListener(new ActionListener()
{
public void actionPerformed(ActionEvent e)
{
s+=8;
s2+=8;
tf.setText(s);
}
}
);
bt[10].addActionListener(new ActionListener()
{
public void actionPerformed(ActionEvent e)
{
s+=9;
s2+=9;
tf.setText(s);
}
}
);
bt[12].addActionListener(new ActionListener()
{
public void actionPerformed(ActionEvent e)
{
s+=0;
s2+=0;
tf.setText(s);
}
}
);
bt[13].addActionListener(new ActionListener()
{
public void actionPerformed(ActionEvent e)
{
s+='.';
s2+='.';
tf.setText(s);
}
}
);
bt[3].addActionListener(new ActionListener()
{
public void actionPerformed(ActionEvent e)
{
s1=s;
s+='+';
id=1;
s2="";
tf.setText(s);
}
}
);
bt[7].addActionListener(new ActionListener()
{
public void actionPerformed(ActionEvent e)
{
s1=s;
s+='-';
id=2;
s2="";
tf.setText(s);
}
}
);
bt[11].addActionListener(new ActionListener()
{
public void actionPerformed(ActionEvent e)
{
s1=s;
s+='*';
id=3;
s2="";
tf.setText(s);
}
}
);
bt[14].addActionListener(new ActionListener()
{
public void actionPerformed(ActionEvent e)
{
s="";
s2="";
tf.setText(s);
}
}
);
bt[15].addActionListener(new ActionListener()
{
public void actionPerformed(ActionEvent e)
{
s1=s;
s+='/';
id=4;
s2="";
tf.setText(s);
}
}
);
bt1.addActionListener(new ActionListener()
{
public void actionPerformed(ActionEvent e)
{
if(id<1) ;
else{
s+='=';
double a=Double.parseDouble(s1);
double b=Double.parseDouble(s2);
double c=0;
switch(id)
{
case 1:c=a+b; break;
case 2:c=a-b; break;
case 3:c=a*b; break;
case 4:c=a/b; break;
}
s+=c;
tf.setText(s);
}
s="";s1="";s2="";id=0;
}
}
);
bt2.addActionListener(new ActionListener()
{
public void actionPerformed(ActionEvent e)
{
char[] c1;
char[] c2=new char[s.length()-1];
c1=s.toCharArray();
for(int i=0;i<s.length()-1;i++)
c2[i]=c1[i];
s=s.valueOf(c2);
if(id<1)
{
s1=s;
}
if(s2.length()>=1)
{
char[] c3;
char[] c4=new char[s2.length()-1];
c3=s2.toCharArray();
for(int i=0;i<s2.length()-1;i++)
c4[i]=c3[i];
s2=s2.valueOf(c4);
}
tf.setText(s);
}
}
);
}
}
如何使用java实现加减乘除运算
在第一步中的java类中，定义减法的方法。定义方式跟加法类似，只要把加法中的“+”号修改为“-”，再修改方法名。见下图所示：
如何使用java实现加减乘除运算
在第一步中的java类中，定义乘法的方法。定义方式为声明两变量相乘并赋值，返回的类型不再是int，一般则定义为double。见下图所示：
如何使用java实现加减乘除运算
在第一步中的java类中，定义除法的方法。与乘法基本一样。除数不能为0，所以要进行判断一下。见下图所示：
如何使用java实现加减乘除运算
最后在main函数中，实例化该java类，并通过实例化的别名点方法名实现调用加减乘除的方法（如：例子中的TestHello test = new TestHello();test.sum(8, 9)；），右键运行控制台打印出结果。见下图所示：
如何使用java实现加减乘除运算
补充一下：细心的同学，应该注意到通过实例化的别名点方法名又赋值给另外一个变量，这个也可以省略，直接修改为System.out.println(int sum = test.sum(8, 9));这种方式打印出来。见下图所示：
如何使用java实现加减乘除运算
使用java实现加减乘除已讲述完毕，相信你会成功实现。另外，所有的方法及结果展示，如下图所示：
如何使用java实现加减乘除运算
如何使用java实现加减乘除运算
import java.awt.Button;
import java.awt.Container;
import java.awt.Frame;
import java.awt.GridLayout;
import java.awt.Panel;
import java.awt.TextField;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.WindowAdapter;
import java.awt.event.WindowEvent;
class CalculatorPanel extends Panel implements ActionListener
{
private final TextField display;
private boolean start=true;
private String op="=";
private double arg=0;
public CalculatorPanel() {
setLayout(new BorderLayout());
display = new TextField("0");
display.setEditable(false);
add(display,"North");
Panel p = new Panel();
p.setLayout(new GridLayout(4,4));
String buttons="789/456*123-0.=+";
for (int i = 0; i < buttons.length(); i++)
{
addButton(p,buttons.substring(i, i+1));
}
add(p,"Center");
}
@Override
public void actionPerformed(ActionEvent evt) {
String s = evt.getActionCommand();
if ('0' <= s.charAt(0) && s.charAt(0) <= '9'|| s.equals("."))
{
if (start)
{
display.setText(s);
} else{
display.setText(display.getText() + s);
}
start = false;
}
else{
if (start){
if (s.equals("-")) {
display.setText(s);
start = false;
}
else
{
op = s;
}
}
else{
double x = Double.parseDouble(display.getText());
calculate(x);
op = s;
start = true;
}
}
}
public void calculate(double n) {
if (op.equals("+")) arg += n;
else if (op.equals("-")) arg -= n;
else if (op.equals("*")) arg *= n;
else if (op.equals("/")) arg /= n;
else if (op.equals("=")) arg = n;
display.setText("" + arg);
}
private void addButton(Container c, String s) {
Button b = new Button(s);
c.add(b);
b.addActionListener(this);
}
}
class CalculatorFrame extends Frame
{
public CalculatorFrame() {
setTitle("Calculator");
setSize(300,200);
setResizable(false);
// pack();
addWindowListener(new WindowAdapter()
{
public void windowClosing(WindowEvent e)
{
System.exit(0);
}
}
);
this.add(new CalculatorPanel());
}
}
public class MyAWTCalculator {
public static void main(String[] args) {
// TODO code application logic here
CalculatorFrame calculatorframe = new CalculatorFrame();
calculatorframe.setVisible(true);
}
}
