Android studio实现简单的计算器

本文实例为大家分享了Android studio实现简单计算器的具体代码，供大家参考，具体内容如下

需求分析及概要设计

目的

开发一个简单的计算器App,使之能够完成加减乘除混合运算

工具及环境

使用java语言，在Android studio平台上进行开发

功能设计

• “+”:实现两数相加
• “-”:实现两数相减
• “*”:实现两数相乘
• “/”:实现两数相除
• “=”:计算并得出正确结果
• “C”:清屏
• “Backspace”:倒退
  

设计思路

1、首先设计一个可视化的界面，供用户输入数据并查看结果。
2、用户可通过点击相应按钮输入正确的表达式（注意：这里只实现对正确表达式的计算处理），最后按"="得出正确结果。在计算过程中可以通过点击倒退键修改输入内容，在进行下一次的运算之前必须先进行清零操作。
3、设计好的计算器应可以进行加减乘除混合四则运算，且可以进行小数和整数运算

详细设计

当用户点击按钮时，用SringBuilder变量记录其输入的运算式，并显示到文本区中。

当用户点击"="时，把文本区的运算式拿出来，首先将它内部的一个一个字节拼接成独立的运算数和运算符，然后存储在一个ArrayList数组中，接着再新建两个ArrayList数组，用来分别存放运算数和运算符，然后遍历存储运算式的ArrayList数组，把其中的运算数和运算符分别放进不同的ArrayList中，每一次放置运算符时，都要先和已存在的运算符进行比较，若要放进的运算符优先级低于或等于运算符数组中的运算符，则弹出一个运算符，并从运算数数组中弹出两个运算数，然后进行运算，并把结果送入运算数数组中，直到遇到比自己优先级低的运算符或运算符数组为空时，则送入该运算符。当遍历到运算式末尾时，依次弹出运算符中的运算符，并对应弹出运算数进行运算直到运算符数组为空，此时运算数数组中只有一个数据就是最终的结果

代码

MainAcivity.java

package com.example.qw.calculator;

import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import java.lang.reflect.Method;
import java.math.BigDecimal;
import java.util.ArrayList;
import java.util.List;

public class MainActivity extends AppCompatActivity{

 private StringBuilder show_equation=new StringBuilder();//显示运算式
 private ArrayList calculate_equation;//计算式
 private int signal=0;//为0 时表示刚输入状态；为1 时表示当前在输出结果上继续输入
 @Override
 protected void onCreate(Bundle savedInstanceState) {
 super.onCreate(savedInstanceState);
 setContentView(R.layout.activity_main);
 //初始化
 show_equation=new StringBuilder();
 calculate_equation=new ArrayList<>();
 Button zero=(Button)findViewById(R.id.zero);
 Button one=(Button)findViewById(R.id.one);
 Button two=(Button)findViewById(R.id.two);
 Button three=(Button)findViewById(R.id.three);
 Button four=(Button)findViewById(R.id.four);
 Button five=(Button)findViewById(R.id.five);
 Button six=(Button)findViewById(R.id.six);
 Button seven=(Button)findViewById(R.id.seven);
 Button eight=(Button)findViewById(R.id.eight);
 Button nine=(Button)findViewById(R.id.nine);
 Button cls=(Button)findViewById(R.id.cls);
 Button div=(Button)findViewById(R.id.div);
 Button mul=(Button)findViewById(R.id.mul);
 Button backspace=(Button)findViewById(R.id.Backspace);
 Button sub=(Button)findViewById(R.id.sub);
 Button add=(Button)findViewById(R.id.add);
 final Button equal=(Button)findViewById(R.id.equal);
 final Button point=(Button)findViewById(R.id.spot);
 final EditText result=(EditText)findViewById(R.id.result);
 result.setCursorVisible(true);
 disableShowInput(result);
 //点击文本框时光标始终在文本末尾
 result.setOnClickListener(new View.OnClickListener() {
  @Override
  public void onClick(View view) {
  result.setSelection(result.getText().length());
  }
 });
 zero.setOnClickListener(new View.OnClickListener() {
  @Override
  public void onClick(View v){
   if(!(show_equation.toString().equals("0"))){
   if(signal==0){
    show_equation.append("0");
    result.setText(show_equation);
    result.setSelection(result.getText().length());
   }else{
    show_equation.delete(0,show_equation.length());
    show_equation.append("0");
    result.setText(show_equation);
    result.setSelection(result.getText().length());
    signal=0;
   }
   }
  }
 });
 one.setOnClickListener(new View.OnClickListener() {
  @Override
  public void onClick(View v) {
  if(signal==0){
   show_equation.append("1");
   result.setText(show_equation);
   result.setSelection(result.getText().length());
  }else{
   show_equation.delete(0,show_equation.length());
   show_equation.append("1");
   result.setText(show_equation);
   result.setSelection(result.getText().length());
   signal=0;
  }
  }
 });
 two.setOnClickListener(new View.OnClickListener() {
  @Override
  public void onClick(View v) {
  if(signal==0){
   show_equation.append("2");
   result.setText(show_equation);
   result.setSelection(result.getText().length());
  }else{
   show_equation.delete(0,show_equation.length());
   show_equation.append("2");
   result.setText(show_equation);
   result.setSelection(result.getText().length());
   signal=0;
  }
  }
 });
 three.setOnClickListener(new View.OnClickListener() {
  @Override
  public void onClick(View v) {
  if(signal==0){
   show_equation.append("3");
   result.setText(show_equation);
   result.setSelection(result.getText().length());
  }else{
   show_equation.delete(0,show_equation.length());
   show_equation.append("3");
   result.setText(show_equation);
   result.setSelection(result.getText().length());
   signal=0;
  }
  }
 });
  four.setOnClickListener(new View.OnClickListener() {
  @Override
  public void onClick(View v) {
  if(signal==0){
   show_equation.append("4");
   result.setText(show_equation);
   result.setSelection(result.getText().length());
  }else{
   show_equation.delete(0,show_equation.length());
   show_equation.append("4");
   result.setText(show_equation);
   result.setSelection(result.getText().length());
   signal=0;
  }
  }
 });
 five.setOnClickListener(new View.OnClickListener() {
  @Override
  public void onClick(View v) {
  if(signal==0){
   show_equation.append("5");
   result.setText(show_equation);
   result.setSelection(result.getText().length());
  }else{
   show_equation.delete(0,show_equation.length());
   show_equation.append("5");
   result.setText(show_equation);
   result.setSelection(result.getText().length());
   signal=0;
  }
  }
 });
 six.setOnClickListener(new View.OnClickListener() {
  @Override
  public void onClick(View v) {
  if(signal==0){
   show_equation.append("6");
   result.setText(show_equation);
   result.setSelection(result.getText().length());
  }else{
   show_equation.delete(0,show_equation.length());
   show_equation.append("6");
   result.setText(show_equation);
   result.setSelection(result.getText().length());
   signal=0;
  }
  }
 });
 seven.setOnClickListener(new View.OnClickListener() {
  @Override
  public void onClick(View v) {
  if(signal==0){
   show_equation.append("7");
   result.setText(show_equation);
   result.setSelection(result.getText().length());
  }else{
   show_equation.delete(0,show_equation.length());
   show_equation.append("7");
   result.setText(show_equation);
   result.setSelection(result.getText().length());
   signal=0;
  }
  }
 });
 eight.setOnClickListener(new View.OnClickListener() {
  @Override
  public void onClick(View v) {
  if(signal==0){
   show_equation.append("8");
   result.setText(show_equation);
   result.setSelection(result.getText().length());
  }else{
   show_equation.delete(0,show_equation.length());
   show_equation.append("8");
   result.setText(show_equation);
   result.setSelection(result.getText().length());
   signal=0;
  }
  }
 });
 nine.setOnClickListener(new View.OnClickListener() {
  @Override
  public void onClick(View v) {
  if(signal==0){
   show_equation.append("9");
   result.setText(show_equation);
   result.setSelection(result.getText().length());
  }else{
   show_equation.delete(0,show_equation.length());
   show_equation.append("9");
   result.setText(show_equation);
   result.setSelection(result.getText().length());
   signal=0;
  }
  }
 });
 cls.setOnClickListener(new View.OnClickListener() {
  @Override
  public void onClick(View v) {
  show_equation.delete(0,show_equation.length());
  calculate_equation.clear();
  signal=0;
  result.setText("");
  }
 });
 backspace.setOnClickListener(new View.OnClickListener() {
  @Override
  public void onClick(View v) {
  if(!(show_equation.toString().equals(""))) {
   if(signal==0){
   show_equation.deleteCharAt(show_equation.length() - 1);
   result.setText(show_equation);
   result.setSelection(result.getText().length());
   }else{
   show_equation.delete(0,show_equation.length());
   result.setText("");
   signal=0;
   }
  }
  }
 });
 point.setOnClickListener(new View.OnClickListener() {
  @Override
  public void onClick(View v) {
  if(signal==0){
   String a=show_equation.toString();
   if(a.equals("")){
   show_equation.append(".");
   result.setText(show_equation);
   result.setSelection(result.getText().length());
   }else{
   int i;
   char t='0';
   for(i=a.length();i>0;i--){
    t=a.charAt(i-1);
    if(t=='.'||t=='+'||t=='-'||t=='*'||t=='/')
    break;
   }
   if(i==0){
    show_equation.append(".");
    result.setText(show_equation);
    result.setSelection(result.getText().length());
   }else if(t=='+'||t=='-'||t=='*'||t=='/'){
    show_equation.append(".");
    result.setText(show_equation);
    result.setSelection(result.getText().length());
   }
   }
  }else{
   show_equation.delete(0,show_equation.length());
   show_equation.append(".");
   result.setText(".");
   result.setSelection(result.getText().length());
   signal=0;
  }
  }
 });

 equal.setOnClickListener(new View.OnClickListener() {
  @Override
  public void onClick(View v) {
  //判断用户是否输入了内容
  if(!show_equation.toString().equals("")){
   signal=1;
   char temp=show_equation.charAt(show_equation.length()-1);
   if(show_equation.charAt(0)=='-')
   show_equation.insert(0,"0");
   if(temp=='+'||temp=='-')
   show_equation.append("0");
   if(temp=='*'||temp=='/')
   show_equation.append("1");
   StringBuilder temp1=new StringBuilder();
   for(int i=0;i='0'&&show_equation.charAt(i)<='9'||show_equation.charAt(i)=='.'){
    temp1.append(String.valueOf(show_equation.charAt(i)));
   }else if(show_equation.charAt(i)=='N'){
    calculate_equation.add("NaN");
    //跳过2个字符
    i=i+2;
   }else if(show_equation.charAt(i)=='∞'){
    calculate_equation.add("∞");
   }
   else
   {
    if(temp1.length()!=0){
    calculate_equation.add(temp1.toString());
    temp1.delete(0,temp1.length());
    }
    calculate_equation.add(String.valueOf(show_equation.charAt(i)));
   }
   }
   if(temp1.length()!=0){
   calculate_equation.add(temp1.toString());
   }
   calculate_equation.add("#");
   String temp8=calculate(calculate_equation);
   result.setText(temp8);
   result.setSelection(result.getText().length());
   show_equation.delete(0,show_equation.length());
   calculate_equation.clear();
   show_equation.append(temp8);
  }
  }
 });
 add.setOnClickListener(new View.OnClickListener() {
  @Override
  public void onClick(View v) {
  //判断用户是否输入了内容
  if(!(show_equation.toString().equals(""))) {
   signal=0;
   char temp=show_equation.charAt(show_equation.length()-1);
   if(temp=='+'||temp=='-'||temp=='*'||temp=='/')
   {
   show_equation.deleteCharAt(show_equation.length()-1);
   show_equation.append("+");
   }
   else
   show_equation.append("+");
   result.setText(show_equation);
   result.setSelection(result.getText().length());
  }
  }
 });
 sub.setOnClickListener(new View.OnClickListener() {
  @Override
  public void onClick(View v) {
  //判断用户是否输入了内容
  if(!(show_equation.toString().equals(""))) {
   signal=0;
   char temp=show_equation.charAt(show_equation.length()-1);
   if(temp=='+'||temp=='-'||temp=='*'||temp=='/')
   {
   show_equation.deleteCharAt(show_equation.length()-1);
   show_equation.append("-");
   }
   else
   show_equation.append("-");
   result.setText(show_equation);
   result.setSelection(result.getText().length());
  }
  }
 });

 mul.setOnClickListener(new View.OnClickListener() {
  @Override
  public void onClick(View v) {
  //判断用户是否输入了内容
  if(!(show_equation.toString().equals(""))) {
   signal=0;
   char temp=show_equation.charAt(show_equation.length()-1);
   if(temp=='+'||temp=='-'||temp=='*'||temp=='/')
   {
   show_equation.deleteCharAt(show_equation.length()-1);
   show_equation.append("*");
   }
   else
   show_equation.append("*");
   result.setText(show_equation);
   result.setSelection(result.getText().length());
  }
  }
 });

 div.setOnClickListener(new View.OnClickListener() {
  @Override
  public void onClick(View v) {
  //判断用户是否输入了内容
  if(!(show_equation.toString().equals(""))) {
   signal=0;
   char temp=show_equation.charAt(show_equation.length()-1);
   if(temp=='+'||temp=='-'||temp=='*'||temp=='/')
   {
   show_equation.deleteCharAt(show_equation.length()-1);
   show_equation.append("/");
   }
   else
   show_equation.append("/");
   result.setText(show_equation);
   result.setSelection(result.getText().length());
  }
  }
 });
 }
 protected boolean operatorPriorityCompare(char operator1,char operator2)
 {
 int o1=0;
 int o2=0;
 switch (operator1){
  case '+':{o1=0;break;}
  case '-':{o1=0;break;}
  case '*':{o1=1;break;}
  case '/':{o1=1;break;}
 }
 switch (operator2){
  case '+':{o2=0;break;}
  case '-':{o2=0;break;}
  case '*':{o2=1;break;}
  case '/':{o2=1;break;}
 }
 if(o1<=o2)
 {
  return false;
 }
 else
  return true;
 }
 //相加
 public static Double Add(Double d1,Double d2) {
 if(d1==Double.NEGATIVE_INFINITY||d1==Double.POSITIVE_INFINITY||d2==Double.NEGATIVE_INFINITY||d2==Double.POSITIVE_INFINITY){
  return d1+d2;
 }
 if(String.valueOf(d1).equals("NaN")||String.valueOf(d1).equals("NaN")){
  return d1+d2;
 }
 BigDecimal b1 = new BigDecimal(Double.toString(d1));
 BigDecimal b2 = new BigDecimal(Double.toString(d2));
 return b1.add(b2).doubleValue();
 }
 //相减
 public static Double Sub(Double d1,Double d2){
 if(d1==Double.NEGATIVE_INFINITY||d1==Double.POSITIVE_INFINITY||d2==Double.NEGATIVE_INFINITY||d2==Double.POSITIVE_INFINITY){
  return d1-d2;
 }
 if(String.valueOf(d1).equals("NaN")||String.valueOf(d1).equals("NaN")){
  return d1-d2;
 }
 if(String.valueOf(d1).equals("NaN")||String.valueOf(d1).equals("NaN")){
  return d1*d2;
 }
 BigDecimal b1=new BigDecimal(Double.toString(d1));
 BigDecimal b2=new BigDecimal(Double.toString(d2));
 return b1.subtract(b2).doubleValue();
 }
 //相乘
 public static Double Mul(Double d1,Double d2){
 if(d1==Double.NEGATIVE_INFINITY||d1==Double.POSITIVE_INFINITY||d2==Double.NEGATIVE_INFINITY||d2==Double.POSITIVE_INFINITY){
  return d1*d2;
 }
 if(String.valueOf(d1).equals("NaN")||String.valueOf(d1).equals("NaN")){
  return d1*d2;
 }
 BigDecimal b1=new BigDecimal(Double.toString(d1));
 BigDecimal b2=new BigDecimal(Double.toString(d2));
 return b1.multiply(b2).setScale(8).doubleValue();
 }
 //相除
 public static Double Div(Double d1,Double d2){
 if(d1==Double.NEGATIVE_INFINITY||d1==Double.POSITIVE_INFINITY||d2==Double.NEGATIVE_INFINITY||d2==Double.POSITIVE_INFINITY){
  return d1/d2;
 }
 if(String.valueOf(d1).equals("NaN")||String.valueOf(d1).equals("NaN")){
  return d1/d2;
 }
 if(d1==0.0&&d2==0.0){
  return Double.NaN;
 }
 if(d2==0.0){
  return d1/d2;
 }
 BigDecimal b1=new BigDecimal(Double.toString(d1));
 BigDecimal b2=new BigDecimal(Double.toString(d2));
 return b1.divide(b2,8,BigDecimal.ROUND_HALF_UP).doubleValue();
 }
 protected String calculate(ArrayList equation){
 Double temp2;
 Double temp3;
 Double result;
 List operator=new ArrayList();
 List operand=new ArrayList();
 for(int i=0;i0)
  {
   String temp5=operator.get(operator.size()-1).toString();
   while(!(operatorPriorityCompare(temp4.charAt(0),temp5.charAt(0)))&&operator.size()>0)
   {
   operator.remove(operator.size()-1);
   temp3=operand.get(operand.size()-1);
   operand.remove(operand.size()-1);
   temp2=operand.get(operand.size()-1);
   operand.remove(operand.size()-1);
   switch (temp5.charAt(0)){
    case '+':{result=Add(temp2,temp3);operand.add(result);break;}
    case '-':{result=Sub(temp2,temp3);operand.add(result);break;}
    case '*':{result=Mul(temp2,temp3);operand.add(result);break;}
    case '/':{result=Div(temp2,temp3);operand.add(result);break;}
   }
   if(operator.size()>0)
   {
    temp5=operator.get(operator.size()-1).toString();
   }
   else
    break;
   }
   operator.add(temp4);
  }
  else
   operator.add(temp4);
  }
  else if(temp4.equals("#"))
  {
  while(operator.size()>0)
  {
   String temp6=(String)operator.get(operator.size()-1);
   operator.remove(operator.size()-1);
   temp3=operand.get(operand.size()-1);
   operand.remove(operand.size()-1);
   temp2=operand.get(operand.size()-1);
   operand.remove(operand.size()-1);
   switch (temp6.charAt(0)){
   case '+':{result=Add(temp2,temp3);operand.add(result);break;}
   case '-':{result=Sub(temp2,temp3);operand.add(result);break;}
   case '*':{result=Mul(temp2,temp3);operand.add(result);break;}
   case '/':{result=Div(temp2,temp3);operand.add(result);break;}
   }
  }
  }
  else
  {
  if(temp4.equals("NaN")){
   operand.add(Double.NaN);
  }else if(temp4.equals("∞")){
   operand.add(Double.POSITIVE_INFINITY);
  }else{
   operand.add(Double.parseDouble(temp4));
  }
  }
 }
 if(operand.get(0)==Double.NEGATIVE_INFINITY) return "-∞";
 if(operand.get(0)==Double.POSITIVE_INFINITY) return "∞";
 return operand.get(0).toString();
 }
 //当API最低版小于21时使用这个函数实现点击文本框不弹出键盘
 public void disableShowInput(EditText et) {
 Class cls = EditText.class;
 Method method;
 try {
  method = cls.getMethod("setShowSoftInputOnFocus", boolean.class);
  method.setAccessible(true);
  method.invoke(et, false);
 } catch (Exception e) {
  e.printStackTrace();
 }
 }
}

activity_main.xml

buttonstytle.xml

####结果分析

启动计算器并输入运算式“59.0-8/46+2”如下图：

结果如下图：

总结

这次做计算器收获很大，首先我对Android studio中的布局有了更深刻的认识，其次在这次编程中熟悉了怎么设置断点调试以快速的找出问题所在。当然，这次的作品也是不够成熟的，因为没有做有关错误表达式的相应处理，因为时间和精力有限，这次只能先做这么多了

注： 今天没事又看了一下这个代码，发现问题很多，简直是惨不忍睹（希望没坑到你们）。比如直接按加、减、乘、除和等号键及后退键会闪退，刚开始一直按 “0” 可以一直输入0，同一个数中可以输入多个小数点等等，我感到很惭愧哈，本人能力有限，不过还是抽时间又改了一下，修复了这些bug，另外也优化了一些东西，上面贴的代码我已经更新了，GitHub上的源码我很快也会更新的，哪里做的不好也希望大家不吝赐教哈 -2018/11/5

链接：源代码下载地址

更多计算器功能实现，请点击专题： 计算器功能汇总 进行学习

关于Android计算器功能的实现，查看专题：Android计算器 进行学习。

以上就是本文的全部内容，希望对大家的学习有所帮助，也希望大家多多支持脚本之家。