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

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<show_equation.length();i++){ if(show_equation.charAt(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<Double> operand=new ArrayList(); for(int i=0;i<equation.size();i++) { String temp4=(String) equation.get(i); if(temp4.equals('+')||temp4.equals('-')||temp4.equals('*')||temp4.equals('/')) { if(operator.size()>0) { 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<EditText> 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

<?xml version='1.0' encoding='utf-8'?><LinearLayout xmlns:android='http://schemas.android.com/apk/res/android' android:orientation='vertical' android:layout_width='match_parent' android:layout_height='match_parent'> <EditText android: android:layout_width='match_parent' android:layout_height='wrap_content' android:textSize='40sp' android:enabled='false'/> <LinearLayout android:layout_width='match_parent' android:layout_height='0dp' android:layout_weight='1' android:orientation='horizontal'> <Button android: android:layout_width='0dp' android:layout_height='match_parent' android:layout_weight='1' android:textSize='20sp' android:text='C' android:background='@drawable/buttonstytle' android:textColor='#ffffff'/> <Button android: android:layout_width='0dp' android:layout_height='match_parent' android:layout_weight='1' android:textSize='20sp' android:text='/' android:background='@drawable/buttonstytle' android:textColor='#ffffff'/> <Button android: android:layout_width='0dp' android:layout_height='match_parent' android:layout_weight='1' android:textSize='20sp' android:text='*' android:background='@drawable/buttonstytle' android:textColor='#ffffff'/> <Button android: android:layout_width='0dp' android:layout_height='match_parent' android:layout_weight='1' android:textSize='20sp' android:text='Backspace' android:textAllCaps='false' android:background='@drawable/buttonstytle' android:textColor='#ffffff'/> </LinearLayout> <LinearLayout android:layout_width='match_parent' android:layout_height='0dp' android:layout_weight='1' android:orientation='horizontal'> <Button android: android:layout_width='0dp' android:layout_height='match_parent' android:layout_weight='1' android:textSize='20sp' android:text='7' android:background='@drawable/buttonstytle' android:textColor='#ffffff'/> <Button android: android:layout_width='0dp' android:layout_height='match_parent' android:layout_weight='1' android:textSize='20sp' android:text='8' android:background='@drawable/buttonstytle' android:textColor='#ffffff'/> <Button android: android:layout_width='0dp' android:layout_height='match_parent' android:layout_weight='1' android:textSize='20sp' android:text='9' android:background='@drawable/buttonstytle' android:textColor='#ffffff'/> <Button android: android:layout_width='0dp' android:layout_height='match_parent' android:layout_weight='1' android:textSize='20sp' android:text='-' android:background='@drawable/buttonstytle' android:textColor='#ffffff'/> </LinearLayout> <LinearLayout android:layout_width='match_parent' android:layout_height='0dp' android:layout_weight='1' android:orientation='horizontal'> <Button android: android:layout_width='0dp' android:layout_height='match_parent' android:layout_weight='1' android:textSize='20sp' android:text='4' android:background='@drawable/buttonstytle' android:textColor='#ffffff'/> <Button android: android:layout_width='0dp' android:layout_height='match_parent' android:layout_weight='1' android:textSize='20sp' android:text='5' android:background='@drawable/buttonstytle' android:textColor='#ffffff'/> <Button android: android:layout_width='0dp' android:layout_height='match_parent' android:layout_weight='1' android:textSize='20sp' android:text='6' android:background='@drawable/buttonstytle' android:textColor='#ffffff'/> <Button android: android:layout_width='0dp' android:layout_height='match_parent' android:layout_weight='1' android:textSize='20sp' android:text='+' android:background='@drawable/buttonstytle' android:textColor='#ffffff'/> </LinearLayout> <LinearLayout android:layout_width='match_parent' android:layout_height='0dp' android:layout_weight='2' android:orientation='horizontal'> <LinearLayout android:layout_width='0dp' android:layout_height='match_parent' android:layout_weight='1' android:orientation='vertical'> <LinearLayout android:layout_width='match_parent' android:layout_height='1dp' android:layout_weight='1' android:orientation='horizontal'> <Button android: android:layout_width='0dp' android:layout_height='match_parent' android:layout_weight='1' android:textSize='20sp' android:text='1' android:background='@drawable/buttonstytle' android:textColor='#ffffff'/> <Button android: android:layout_width='0dp' android:layout_height='match_parent' android:layout_weight='1' android:textSize='20sp' android:text='2' android:background='@drawable/buttonstytle' android:textColor='#ffffff'/> </LinearLayout> <LinearLayout android:layout_width='match_parent' android:layout_height='1dp' android:layout_weight='1'> <Button android: android:layout_width='match_parent' android:layout_height='match_parent' android:text='0' android:textSize='20sp' android:background='@drawable/buttonstytle' android:textColor='#ffffff'/> </LinearLayout> </LinearLayout> <LinearLayout android:layout_width='0dp' android:layout_height='match_parent' android:layout_weight='1' android:orientation='horizontal'> <LinearLayout android:layout_width='0dp' android:layout_height='match_parent' android:layout_weight='1' android:orientation='vertical'> <Button android: android:layout_width='match_parent' android:layout_height='1dp' android:layout_weight='1' android:text='3' android:textSize='20sp' android:background='@drawable/buttonstytle' android:textColor='#ffffff'/> <Button android: android:layout_width='match_parent' android:layout_height='1dp' android:layout_weight='1' android:text='.' android:textSize='20sp' android:background='@drawable/buttonstytle' android:textColor='#ffffff'/> </LinearLayout> <LinearLayout android:layout_width='0dp' android:layout_height='match_parent' android:layout_weight='1'> <Button android: android:layout_width='match_parent' android:layout_height='match_parent' android:text='=' android:textSize='20sp' android:background='@drawable/buttonstytle' android:textColor='#ffffff'/> </LinearLayout> </LinearLayout></LinearLayout></LinearLayout>

buttonstytle.xml

<?xml version='1.0' encoding='utf-8'?><shape xmlns:android='http://schemas.android.com/apk/res/android' > <!-- 主体背景颜色值 --> <solid android:color='#666666' /> <!-- 连框宽度和颜色值 --> <stroke android: android:color='#FFFFFF' /></shape>

####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。

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