android studio实现简单的计算器功能

<?xml version="1.0" encoding="utf-8"? 
<android.support.constraint.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:id="@+id/next"
android:layout_width="match_parent"
android:layout_height="match_parent"
app:layout_behavior="@string/appbar_scrolling_view_behavior"
tools:context=".MainActivity"
tools:showIn="@layout/activity_main" 
<!--<TextView-- 
<!--android:layout_width="wrap_content"-- 
<!--android:layout_height="wrap_content"-- 
<!--android:text="Hello World!"-- 
<!--app:layout_constraintBottom_toBottomOf="parent"-- 
<!--app:layout_constraintLeft_toLeftOf="parent"-- 
<!--app:layout_constraintRight_toRightOf="parent"-- 
<!--app:layout_constraintTop_toTopOf="parent" / -- 
<LinearLayout
android:layout_width="fill_parent"
android:layout_height="match_parent"
android:orientation="vertical"  
<EditText
android:id="@+id/input"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_gravity="center"
android:editable="false"
android:hint="@string/shuru" / 
<EditText
android:id="@+id/output"
android:layout_width="match_parent"
android:layout_height="70dp"
android:layout_gravity="center"
android:editable="true"
android:gravity="right"
android:hint="@string/shuchu" / 
<RelativeLayout
android:layout_width="350dp"
android:layout_height="wrap_content"
android:layout_gravity="center" 
<Button
android:id="@+id/clear"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentLeft="true"
android:text="@string/clear"
android:textSize="40sp" / 
<Button
android:id="@+id/back"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_toRightOf="@id/clear"
android:text="@string/back"
android:textSize="40sp" / 
<Button
android:id="@+id/divide"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_toRightOf="@id/back"
android:text="@string/divide"
android:textSize="40sp" / 
<Button
android:id="@+id/multiply"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_toRightOf="@id/divide"
android:text="@string/multiply"
android:textSize="40sp" / 
<Button
android:id="@+id/seven"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentLeft="true"
android:layout_below="@id/clear"
android:text="@string/seven"
android:textSize="40sp" / 
<Button
android:id="@+id/eight"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_toRightOf="@id/seven"
android:layout_below="@id/divide"
android:text="@string/eight"
android:textSize="40sp" / 
<Button
android:id="@+id/nine"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_below="@id/multiply"
android:layout_toRightOf="@id/eight"
android:text="@string/nine"
android:textSize="40sp" / 
<Button
android:id="@+id/subtract"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentRight="true"
android:layout_below="@id/multiply"
android:layout_toRightOf="@id/nine"
android:text="@string/subtract"
android:textSize="40sp" / 
<Button
android:id="@+id/four"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentLeft="true"
android:layout_below="@id/seven"
android:text="@string/four"
android:textSize="40sp" / 
<Button
android:id="@+id/five"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_below="@id/eight"
android:layout_toRightOf="@id/four"
android:text="@string/five"
android:textSize="40sp" / 
<Button
android:id="@+id/six"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_below="@id/nine"
android:layout_toRightOf="@id/five"
android:text="@string/six"
android:textSize="40sp" / 
<Button
android:id="@+id/add"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentRight="true"
android:layout_below="@id/subtract"
android:layout_toRightOf="@id/six"
android:text="@string/add"
android:textSize="40sp" / 
<Button
android:id="@+id/one"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentLeft="true"
android:layout_below="@id/four"
android:text="@string/one"
android:textSize="40sp" / 
<Button
android:id="@+id/two"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_below="@id/five"
android:layout_toRightOf="@id/one"
android:text="@string/two"
android:textSize="40sp" / 
<Button
android:id="@+id/three"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_below="@id/six"
android:layout_toRightOf="@id/two"
android:text="@string/three"
android:textSize="40sp" / 
<Button
android:id="@+id/result"
android:layout_width="wrap_content"
android:layout_height="146dp"
android:layout_alignParentRight="true"
android:layout_below="@id/add"
android:layout_toRightOf="@id/three"
android:text="@string/result"
android:textSize="40sp" / 
<Button
android:id="@+id/zero"
android:layout_width="175dp"
android:layout_height="wrap_content"
android:layout_alignParentLeft="true"
android:layout_below="@id/one"
android:text="@string/zero"
android:textSize="40sp" / 
<Button
android:id="@+id/dot"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_below="@id/three"
android:layout_toRightOf="@id/zero"
android:text="@string/dot"
android:textSize="40sp" / 
</RelativeLayout 
</LinearLayout 
</android.support.constraint.ConstraintLayout 

<resources 
<string name="app_name" Calculator</string 
<string name="action_settings" Settings</string 
<string name="title_activity_page2" page2</string 
<string name="next" 下一页</string 
<string name="zero" 0</string 
<string name="one" 1</string 
<string name="two" 2</string 
<string name="three" 3</string 
<string name="four" 4</string 
<string name="five" 5</string 
<string name="six" 6</string 
<string name="seven" 7</string 
<string name="eight" 8</string 
<string name="nine" 9</string 
<string name="add" +</string 
<string name="subtract" -</string 
<string name="multiply" *</string 
<string name="divide" /</string 
<string name="clear" CE</string 
<string name="back" <-</string 
<string name="result" =</string 
<string name="shuru" 请输入：</string 
<string name="shuchu" 结果:</string 
<string name="dot" .</string 
<string name="resultText" 计算式</string 
</resources 

package com.example.dell.calculator;
import android.content.Intent;
import android.os.Bundle;
import android.support.design.widget.FloatingActionButton;
import android.support.design.widget.Snackbar;
import android.support.v7.app.AppCompatActivity;
import android.support.v7.widget.Toolbar;
import android.view.View;
import android.view.Menu;
import android.view.MenuItem;
import android.app.Activity;
import android.content.Context;
import android.view.View.OnClickListener;
import android.widget.CheckBox;
import android.widget.EditText;
import android.widget.Button;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.text.DecimalFormat;
import java.text.NumberFormat;
import java.util.regex.Matcher;
import java.util.regex.Pattern;
public class MainActivity extends AppCompatActivity {
private EditText output = null;
private EditText input = null;
private Button btn0 = null;
private Button btn1 = null;
private Button btn2 = null;
private Button btn3 = null;
private Button btn4 = null;
private Button btn5 = null;
private Button btn6 = null;
private Button btn7 = null;
private Button btn8 = null;
private Button btn9 = null;
private Button btnadd = null;
private Button btnsubtract = null;
private Button btnmultiply = null;
private Button btndivide = null;
private Button btnclear = null;
private Button btnback = null;
private Button btndot = null;
private Button btnresult = null;
private String text = "";//保存输入的数字和符号
private Double result = 0.0;//输出结果
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
setSupportActionBar(toolbar);
output = (EditText) findViewById(R.id.output);
input = (EditText) findViewById(R.id.input);
btn0 = (Button) findViewById(R.id.zero);
btn1 = (Button) findViewById(R.id.one);
btn2 = (Button) findViewById(R.id.two);
btn3 = (Button) findViewById(R.id.three);
btn4 = (Button) findViewById(R.id.four);
btn5 = (Button) findViewById(R.id.five);
btn6 = (Button) findViewById(R.id.six);
btn7 = (Button) findViewById(R.id.seven);
btn8 = (Button) findViewById(R.id.eight);
btn9 = (Button) findViewById(R.id.nine);
btnadd = (Button) findViewById(R.id.add);
btnsubtract = (Button) findViewById(R.id.subtract);
btnmultiply = (Button) findViewById(R.id.multiply);
btndivide = (Button) findViewById(R.id.divide);
btnclear = (Button) findViewById(R.id.clear);
btnback = (Button) findViewById(R.id.back);
btndot = (Button) findViewById(R.id.dot);
btnresult = (Button) findViewById(R.id.result);
//设置按钮侦听事件
btn0.setOnClickListener(listener);
btn1.setOnClickListener(listener);
btn2.setOnClickListener(listener);
btn3.setOnClickListener(listener);
btn4.setOnClickListener(listener);
btn5.setOnClickListener(listener);
btn6.setOnClickListener(listener);
btn7.setOnClickListener(listener);
btn8.setOnClickListener(listener);
btn9.setOnClickListener(listener);
btnadd.setOnClickListener(listener);
btnsubtract.setOnClickListener(listener);
btnmultiply.setOnClickListener(listener);
btndivide.setOnClickListener(listener);
btnclear.setOnClickListener(listener);
btnback.setOnClickListener(listener);
btndot.setOnClickListener(listener);
btnresult.setOnClickListener(listener);
FloatingActionButton fab = (FloatingActionButton) findViewById(R.id.fab);
fab.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
Snackbar.make(view, "Replace with your own action", Snackbar.LENGTH_LONG)
.setAction("Action", null).show();
}
});
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.menu_main, menu);
return true;
}
@Override
public boolean onOptionsItemSelected(MenuItem item) {
// Handle action bar item clicks here. The action bar will
// automatically handle clicks on the Home/Up button, so long
// as you specify a parent activity in AndroidManifest.xml.
int id = item.getItemId();
//noinspection SimplifiableIfStatement
if (id == R.id.action_settings) {
return true;
}
return super.onOptionsItemSelected(item);
}
//public void onClickNext(View view) {
// Intent intent = new Intent(this,page2.class);
// startActivity(intent);
// }
private OnClickListener listener = new OnClickListener() {
public void onClick(View v) {
// TODO Auto-generated method stub
switch (v.getId()) {
//输入数字
case R.id.zero:
num(0);
break;
case R.id.one:
num(1);
break;
case R.id.two:
num(2);
break;
case R.id.three:
num(3);
break;
case R.id.four:
num(4);
break;
case R.id.five:
num(5);
break;
case R.id.six:
num(6);
break;
case R.id.seven:
num(7);
break;
case R.id.eight:
num(8);
break;
case R.id.nine:
num(9);
break;
case R.id.dot:
dot();
break;
//执行运算
case R.id.add:
add();
break;
case R.id.subtract:
sub();
break;
case R.id.multiply:
multiply();
break;
case R.id.divide:
divide();
break;
case R.id.clear:
clear();
break;
case R.id.back:
back();
break;
//计算结果
case R.id.result:
result();
break;
default:
break;
}
input.setText(text);
output.setText(String.valueOf(result));
}
};
private void num(int i) {
// TODO Auto-generated method stub
text = text + String.valueOf(i);
}
private void dot() {
// TODO Auto-generated method stub
text = text + ".";
}
private void clear() {
// TODO Auto-generated method stub
text = "";
result = null;
input.setText("");
output.setText("");
}
private void back() {
// TODO Auto-generated method stub
String str = text.substring(0, text.length()-1);
text = str;
}
private void add() {
// TODO Auto-generated method stub
text += "+";
}
private void sub() {
// TODO Auto-generated method stub
text += "-";
}
private void multiply() {
// TODO Auto-generated method stub
text += "*";
}
private void divide() {
// TODO Auto-generated method stub
text += "/";
}
//计算输出结果
private void result() {
// TODO Auto-generated method stub
result = testOperation(text);
}
public Double testOperation(String s){
//分割字符然后放进数组
String s1 =s.replace("+","-");
String[] str = s1.split("-");
double total1=0;
//先遍历数组，把里面的乘除结果算出来
for(String str1:str){
if(str1.contains("*")||str1.contains("/")){
double total = 0;
for(int i =0;i<str1.length();){
int count =1;
a:for(int j =i+1;j<str1.length();j++){
char c =str1.charAt(j);
if(c=='*'||c=='/'){
break a;
}else{
count++;
}
}
//将数字截取出来
String s2 =str1.substring(i,i+count);
double d = Double.parseDouble(s2);
if(i==0){
total = d;
}else{
char c1 = str1.charAt(i-1);
if(c1=='*'){
total*=d;
}else if(c1=='/'){
//如果除数为0，直接返回null;
if(d == 0)
return null;
total/=d;
}
}
i+=count+1;
}
s= s.replace(str1, total+"");
}
}
//进行加减运算
for(int i =0;i<s.length();i++){
int count =1;
a:for(int j=i+1;j<s.length();j++){
char c = s.charAt(j);
if(c=='+'||c=='-'){
break a;
}else{
count++;
}
}
String s3= s.substring(i,i+count);
double d2 = Double.parseDouble(s3);
if(i==0){
total1 = d2;
}else{
char c = s.charAt(i-1);
if(c=='+'){
total1+=d2;
}else if(c=='-'){
total1-=d2;
}
}
i+=count;
}
return total1;
}
}