Java编写计算器的常见方法实例总结

本文实例总结了java编写计算器的常见方法。分享给大家供大家参考，具体如下：

方法一：

package wanwa;
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
public class calculator extends jframe {
private container container;
private gridbaglayout layout;
private gridbagconstraints constraints;
private jtextfield displayfield;// 计算结果显示区
private string lastcommand;// 保存+,-,*,/,=命令
private double result;// 保存计算结果
private boolean start;// 判断是否为数字的开始
public calculator() {
super("calculator");
container = getcontentpane();
layout = new gridbaglayout();
container.setlayout(layout);
constraints = new gridbagconstraints();
start = true;
result = 0;
lastcommand = "=";
displayfield = new jtextfield(20);
displayfield.sethorizontalalignment(jtextfield.right);
constraints.gridx = 0;
constraints.gridy = 0;
constraints.gridwidth = 4;
constraints.gridheight = 1;
constraints.fill = gridbagconstraints.both;
constraints.weightx = 100;
constraints.weighty = 100;
layout.setconstraints(displayfield, constraints);
container.add(displayfield);
actionlistener insert = new insertaction();
actionlistener command = new commandaction();
// addbutton("backspace", 0, 1, 2, 1, insert);
// addbutton("ce", 2, 1, 1, 1, insert);
// addbutton("c", 3, 1, 1, 1, insert);
addbutton("7", 0, 2, 1, 1, insert);
addbutton("8", 1, 2, 1, 1, insert);
addbutton("9", 2, 2, 1, 1, insert);
addbutton("/", 3, 2, 1, 1, command);
addbutton("4", 0, 3, 1, 1, insert);
addbutton("5", 1, 3, 1, 1, insert);
addbutton("6", 2, 3, 1, 1, insert);
addbutton("*", 3, 3, 1, 1, command);
addbutton("1", 0, 4, 1, 1, insert);
addbutton("2", 1, 4, 1, 1, insert);
addbutton("3", 2, 4, 1, 1, insert);
addbutton("-", 3, 4, 1, 1, command);
addbutton("0", 0, 5, 1, 1, insert);
// addbutton("+/-", 1, 5, 1, 1, insert);// 只显示"-"号,"+"没有实用价值
addbutton(".", 2, 5, 1, 1, insert);
addbutton("+", 3, 5, 1, 1, command);
addbutton("=", 0, 6, 4, 1, command);
this.setresizable(false);
setsize(180, 200);
setvisible(true);
}
private void addbutton(string label, int row, int column, int with,
int height, actionlistener listener) {
jbutton button = new jbutton(label);
constraints.gridx = row;
constraints.gridy = column;
constraints.gridwidth = with;
constraints.gridheight = height;
constraints.fill = gridbagconstraints.both;
button.addactionlistener(listener);
layout.setconstraints(button, constraints);
container.add(button);
}
private class insertaction implements actionlistener {
public void actionperformed(actionevent event) {
string input = event.getactioncommand();
if (start) {
displayfield.settext("");
start = false;
if (input.equals("+/-"))
displayfield.settext(displayfield.gettext() + "-");
}
if (!input.equals("+/-")) {
  if (input.equals("backspace")) {
   string str = displayfield.gettext();
if (str.length() > 0)
  displayfield.settext(str.substring(0, str.length() - 1));
} else if (input.equals("ce") || input.equals("c")) {
displayfield.settext("0");
start = true;
} else
displayfield.settext(displayfield.gettext() + input);
}
}
}
private class commandaction implements actionlistener {
 public void actionperformed(actionevent evt) {
 string command = evt.getactioncommand();
 if (start) {
 lastcommand = command;
 } else {
 calculate(double.parsedouble(displayfield.gettext()));
 lastcommand = command;
 start = true;
 }
}
}
public void calculate(double x) {
if (lastcommand.equals("+"))
result += x;
else if (lastcommand.equals("-"))
result -= x;
else if (lastcommand.equals("*"))
result *= x;
else if (lastcommand.equals("/"))
result /= x;
else if (lastcommand.equals("="))
result = x;
displayfield.settext("" + result);
}
public static void main(string[] args) {
calculator calculator = new calculator();
calculator.setdefaultcloseoperation(jframe.exit_on_close);
}
}

方法二：

import java.awt.*;
import java.awt.event.*;
public class mycalculator {
 private frame f;
 private textfield tf = new textfield(30);
 private long result;
 private boolean append=false;
 private char operator='=';
 private button[] btn=new button[15];
 public mycalculator() {
  initcomponent();
 }
 private void initcomponent() {
  f = new frame("my calculator v1.0");
  f.setlayout(new borderlayout()); //the frame uses borderlayout
  f.addwindowlistener(new windowadapter() {
   public void windowclosing(windowevent evt) {
    system.exit(0);
   }
  });
  panel centerpanel = new panel();
  centerpanel.setlayout(new gridlayout(5, 3)); //the panel uses gridlayout
  numberlistener nl=new numberlistener();
  operatorlistener ol=new operatorlistener();
  btn[10]=new button("+");
  btn[11]=new button("-");
  btn[12]=new button("*");
  btn[13]=new button("/");
  btn[14]=new button("=");
  for (int i=0;i<=9;i++){
   btn[i]=new button(string.valueof(i));
   centerpanel.add(btn[i]);
   btn[i].addactionlistener(nl);
   if (i%2==1){
    centerpanel.add(btn[(i+19)/2]);
    btn[(i+19)/2].addactionlistener(ol);
   }
  }
  f.add(centerpanel, borderlayout.center);
  panel northpanel = new panel();
  tf.seteditable(false);
  northpanel.add(tf);
  f.add(northpanel, borderlayout.north);
 }
 public void go() {
  f.pack();
  f.setvisible(true);
 }
 public static void main(string[] args) {
  new mycalculator().go();
 }
 /**
 *采用成员内部类方式，实现监听器接口，方便访问主类内类内部成员。
 *此类负责数字按钮action事件监听和处理
 */
 class numberlistener implements actionlistener{
  public void actionperformed(actionevent e){
   if (!append) {
    tf.settext("");
    append=true;
   }
   string s=tf.gettext();
   s+=e.getactioncommand();
   tf.settext(s);
   if (!btn[10].isenabled()){
    for(int i=10;i<=14;i++) btn[i].setenabled(true);
   }
  }
 }
 /**
 * 成员内部类，负责操作符按钮的事件处理
 */
 class operatorlistener implements actionlistener{
  public void actionperformed(actionevent e){
   if (!append) return;
   for(int i=10;i<=14;i++) btn[i].setenabled(false);
   string s=tf.gettext();
   long num=long.parselong(s);//get the number of textfield
   append=false; //set append
   switch(operator){
    case '+':result+=num;break;
    case '-':result-=num;break;
    case '*':result*=num;break;
    case '/':{
     if (num==0) result=0;
     else result/=num;
     break;
    }
    case '=':result=num;break;
   }
   tf.settext(string.valueof(result));
   //set the value of result to textfield
   string op=e.getactioncommand();
   operator=op.charat(0); // set operator
  }
 }
}

方法三：

package wanwa;
import java.util.*;
public class calc {
public static void main(string[] args) {
scanner input = new scanner(system.in);
system.out.println("*****************简易计算器****************");
system.out.println("*\t\t\t\t\t*");
system.out.println("* 使用说明： 1.加法 2.减法 3.乘法 4.除法 *");
system.out.println("*\t\t\t\t\t*");
system.out.println("*****************************************");
for(int i=0;i<100;i++){
system.out.print("\n请选择运算规则：");
int num = input.nextint();
switch(num){
case 1:
system.out.println("\n******你选择了加法******\n");
system.out.print("请输入第1个加数:");
int jiashu1 = input.nextint();
system.out.print("请输入第2个加数:");
int jiashu2 = input.nextint();
system.out.println("运算结果为:" + jiashu1 + " + " + jiashu1 + " = " + (jiashu1 + jiashu2));
break;
case 2:
system.out.println("\n******你选择了减法******\n");
system.out.print("请输入被减数:");
int jianshu1 = input.nextint();
system.out.print("请输入减数:");
int jianshu2 = input.nextint();
system.out.println("运算结果为:" + jianshu1 + " - " + jianshu2 + " = " + (jianshu1 - jianshu2));
break;
case 3:
system.out.println("\n******你选择了乘法******\n");
system.out.print("请输入第1个因数:");
int chengfa1 = input.nextint();
system.out.print("请输入第2个因数:");
int chengfa2 = input.nextint();
system.out.println("运算结果为:" + chengfa1 + " * " + chengfa2 + " = " + (chengfa1 * chengfa2));
break;
case 4:
system.out.println("\n******你选择了除法******\n");
system.out.print("请输入被除数:");
double chufa1 = input.nextint();
system.out.print("请输入除数:");
double chufa2 = input.nextint();
system.out.println("运算结果为:" + chufa1 + " / " + chufa2 + " = " + (chufa1 / chufa2) + " 余 " + (chufa1 % chufa2));
break;
default:
system.out.println("\n你的选择有错，请重新选择!");
break;
}
}
}
}

方法四：

package wanwa;
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
public class calculator extends jframe {
private container container;
private gridbaglayout layout;
private gridbagconstraints constraints;
private jtextfield displayfield;// 计算结果显示区
private string lastcommand;// 保存+,-,*,/,=命令
private double result;// 保存计算结果
private boolean start;// 判断是否为数字的开始
public calculator() {
super("calculator");
container = getcontentpane();
layout = new gridbaglayout();
container.setlayout(layout);
constraints = new gridbagconstraints();
start = true;
result = 0;
lastcommand = "=";
displayfield = new jtextfield(20);
displayfield.sethorizontalalignment(jtextfield.right);
constraints.gridx = 0;
constraints.gridy = 0;
constraints.gridwidth = 4;
constraints.gridheight = 1;
constraints.fill = gridbagconstraints.both;
constraints.weightx = 100;
constraints.weighty = 100;
layout.setconstraints(displayfield, constraints);
container.add(displayfield);
actionlistener insert = new insertaction();
actionlistener command = new commandaction();
// addbutton("backspace", 0, 1, 2, 1, insert);
// addbutton("ce", 2, 1, 1, 1, insert);
// addbutton("c", 3, 1, 1, 1, insert);
addbutton("7", 0, 2, 1, 1, insert);
addbutton("8", 1, 2, 1, 1, insert);
addbutton("9", 2, 2, 1, 1, insert);
addbutton("/", 3, 2, 1, 1, command);
addbutton("4", 0, 3, 1, 1, insert);
addbutton("5", 1, 3, 1, 1, insert);
addbutton("6", 2, 3, 1, 1, insert);
addbutton("*", 3, 3, 1, 1, command);
addbutton("1", 0, 4, 1, 1, insert);
addbutton("2", 1, 4, 1, 1, insert);
addbutton("3", 2, 4, 1, 1, insert);
addbutton("-", 3, 4, 1, 1, command);
addbutton("0", 0, 5, 1, 1, insert);
// addbutton("+/-", 1, 5, 1, 1, insert);// 只显示"-"号,"+"没有实用价值
addbutton(".", 2, 5, 1, 1, insert);
addbutton("+", 3, 5, 1, 1, command);
addbutton("=", 0, 6, 4, 1, command);
this.setresizable(false);
setsize(180, 200);
setvisible(true);
}
private void addbutton(string label, int row, int column, int with,
int height, actionlistener listener) {
jbutton button = new jbutton(label);
constraints.gridx = row;
constraints.gridy = column;
constraints.gridwidth = with;
constraints.gridheight = height;
constraints.fill = gridbagconstraints.both;
button.addactionlistener(listener);
layout.setconstraints(button, constraints);
container.add(button);
}
private class insertaction implements actionlistener {
public void actionperformed(actionevent event) {
string input = event.getactioncommand();
if (start) {
displayfield.settext("");
start = false;
if (input.equals("+/-"))
displayfield.settext(displayfield.gettext() + "-");
}
if (!input.equals("+/-")) {
  if (input.equals("backspace")) {
   string str = displayfield.gettext();
if (str.length() > 0)
  displayfield.settext(str.substring(0, str.length() - 1));
} else if (input.equals("ce") || input.equals("c")) {
displayfield.settext("0");
start = true;
} else
displayfield.settext(displayfield.gettext() + input);
}
}
}
private class commandaction implements actionlistener {
 public void actionperformed(actionevent evt) {
 string command = evt.getactioncommand();
 if (start) {
 lastcommand = command;
 } else {
 calculate(double.parsedouble(displayfield.gettext()));
 lastcommand = command;
 start = true;
 }
}
}
public void calculate(double x) {
if (lastcommand.equals("+"))
result += x;
else if (lastcommand.equals("-"))
result -= x;
else if (lastcommand.equals("*"))
result *= x;
else if (lastcommand.equals("/"))
result /= x;
else if (lastcommand.equals("="))
result = x;
displayfield.settext("" + result);
}
public static void main(string[] args) {
calculator calculator = new calculator();
calculator.setdefaultcloseoperation(jframe.exit_on_close);
}
} 

希望本文所述对大家java程序设计有所帮助。