Android Studio实现简易计算器(表格布局TableLayout)

<?xml version="1.0" encoding="utf-8"?>
<shape xmlns:android="http://schemas.android.com/apk/res/android">

 <corners android:radius="5dp"/>
 <solid android:color="#f9f9f9"/>
 <stroke
 android:width="2dp"
 android:color="#ffa600"/>
</shape>

<?xml version="1.0" encoding="utf-8"?>
<shape xmlns:android="http://schemas.android.com/apk/res/android">
 <corners android:radius="5dp"/> // 圆角
 <solid android:color="#F7B684"/> //颜色
</shape>

<?xml version="1.0" encoding="utf-8"?>
<shape xmlns:android="http://schemas.android.com/apk/res/android">


 <corners android:radius="5dp"/>
 <solid android:color="#ffffff"/>
 <stroke
 android:width="1dp"
 android:color="#ffa600"/>

</shape>

<?xml version="1.0" encoding="utf-8"?>
<selector xmlns:android="http://schemas.android.com/apk/res/android">


 <item android:drawable="@drawable/gray"/> //默认颜色
 <item android:drawable="@drawable/orange" android:state_pressed="true"/> //按下的改变的颜色
</selector>

<?xml version="1.0" encoding="utf-8"?>
<TableLayout xmlns:android="http://schemas.android.com/apk/res/android"
 android:layout_width="match_parent"
 android:layout_height="match_parent"

 android:background="#D8ECF3">


 <TextView
 android:gravity="bottom|right"
 android:textSize="70dp"
 android:singleLine="true"
 android:layout_margin="15dp"
 android:layout_width="match_parent"
 android:layout_height="120dp"
 android:background="@drawable/white"
 android:id="@ id/textView"/>


 <TableRow
 android:layout_width="match_parent"
 android:layout_height="match_parent"
 android:layout_marginTop="10dp">

 <Button
 android:id="@ id/btn_clean"
 android:layout_marginLeft="10dp"
 android:background="@drawable/orange"
 android:gravity="center"
 android:text="C"
 android:textSize="25sp" />

 <Button
 android:id="@ id/btn_del"
 android:layout_marginLeft="10dp"
 android:layout_span="2"
 android:background="@drawable/gray"
 android:gravity="center"
 android:text="Del"
 android:textSize="25sp" />

 <Button
 android:id="@ id/btn_divide"
 android:layout_marginLeft="10dp"
 android:layout_marginRight="10dp"
 android:background="@drawable/gray"
 android:gravity="center"
 android:layout_span="1"
 android:text="/"
 android:textSize="25sp" />

 </TableRow>

 <TableRow
 android:layout_width="match_parent"
 android:layout_height="match_parent"
 android:layout_marginTop="10dp">

 <Button
 android:id="@ id/btn_7"
 android:layout_marginLeft="10dp"
 android:background="@drawable/white"
 android:gravity="center"
 android:text="7"
 android:textSize="25sp" />

 <Button
 android:id="@ id/btn_8"
 android:layout_marginLeft="10dp"
 android:background="@drawable/white"
 android:gravity="center"
 android:text="8"
 android:textSize="25sp" />

 <Button
 android:id="@ id/btn_9"
 android:layout_marginLeft="10dp"
 android:background="@drawable/white"
 android:gravity="center"
 android:text="9"
 android:textSize="25sp" />

 <Button
 android:id="@ id/btn_multiply"
 android:layout_marginLeft="10dp"
 android:layout_marginRight="10dp"
 android:background="@drawable/gray"
 android:gravity="center"
 android:text="*"
 android:textSize="25sp" />
 </TableRow>

 <TableRow
 android:layout_width="match_parent"
 android:layout_height="match_parent"
 android:layout_marginTop="10dp">

 <Button
 android:id="@ id/btn_4"
 android:layout_marginLeft="10dp"
 android:background="@drawable/white"
 android:gravity="center"
 android:text="4"
 android:textSize="25sp" />

 <Button
 android:id="@ id/btn_5"
 android:layout_marginLeft="10dp"
 android:background="@drawable/white"
 android:gravity="center"
 android:text="5"
 android:textSize="25sp" />

 <Button
 android:id="@ id/btn_6"
 android:layout_marginLeft="10dp"
 android:background="@drawable/white"
 android:gravity="center"
 android:text="6"
 android:textSize="25sp" />

 <Button
 android:id="@ id/btn_add"
 android:layout_marginLeft="10dp"
 android:layout_marginRight="10dp"
 android:background="@drawable/gray"
 android:gravity="center"
 android:text=" "
 android:textSize="25sp" />
 </TableRow>

 <TableRow
 android:layout_width="match_parent"
 android:layout_height="match_parent"
 android:layout_marginTop="10dp">

 <Button
 android:id="@ id/btn_1"
 android:layout_marginLeft="10dp"
 android:background="@drawable/white"
 android:gravity="center"
 android:text="1"
 android:textSize="25sp" />

 <Button
 android:id="@ id/btn_2"
 android:layout_marginLeft="10dp"
 android:background="@drawable/white"
 android:gravity="center"
 android:text="2"
 android:textSize="25sp" />

 <Button
 android:id="@ id/btn_3"
 android:layout_marginLeft="10dp"
 android:background="@drawable/white"
 android:gravity="center"
 android:text="3"
 android:textSize="25sp" />

 <Button
 android:id="@ id/btn_minus"
 android:layout_marginLeft="10dp"
 android:layout_marginRight="10dp"
 android:background="@drawable/gray"
 android:gravity="center"
 android:text="-"
 android:textSize="25sp" />

 </TableRow>


 <TableRow
 android:layout_width="wrap_content"
 android:layout_height="match_parent"
 android:layout_marginTop="10dp">

 <Button
 android:id="@ id/btn_0"
 android:layout_marginLeft="10dp"
 android:layout_span="2"
 android:background="@drawable/white"
 android:gravity="center"
 android:text="0"
 android:textSize="25sp" />

 <Button
 android:id="@ id/btn_point"
 android:layout_marginLeft="10dp"
 android:layout_span="1"
 android:background="@drawable/white"
 android:gravity="center"
 android:text="."
 android:textSize="25sp" />

 <Button
 android:id="@ id/btn_equal"
 android:layout_marginLeft="10dp"
 android:layout_marginRight="10dp"
 android:layout_span="1"
 android:background="@drawable/gray"
 android:gravity="center"
 android:text="="
 android:textSize="25sp" />


 </TableRow>


</TableLayout>

package com.example.calculator;

import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.TextView;

public class MainActivity extends AppCompatActivity implements View.OnClickListener {

 Button btn_clean,btn_del,btn_divide,btn_0,btn_1,btn_2,btn_3,btn_4,btn_5,btn_6,btn_7,btn_8,btn_9,
 btn_multiply,btn_add,btn_minus,btn_point,btn_equal;
 TextView textView;
 boolean clear_flag;  //清空标识
 @Override
 protected void onCreate(Bundle savedInstanceState) {
 super.onCreate (savedInstanceState);
 setContentView (R.layout.activity_main);
 btn_0 = findViewById(R.id.btn_0); //初始化
 btn_1 = findViewById(R.id.btn_1);
 btn_2 = findViewById(R.id.btn_2);
 btn_3 = findViewById(R.id.btn_3);
 btn_4 = findViewById(R.id.btn_4);
 btn_5 = findViewById(R.id.btn_5);
 btn_6 = findViewById(R.id.btn_6);
 btn_7 = findViewById(R.id.btn_7);
 btn_8 = findViewById(R.id.btn_8);
 btn_9 = findViewById(R.id.btn_9);
 btn_multiply = findViewById(R.id.btn_multiply);
 btn_divide = findViewById(R.id.btn_divide);
 btn_add = findViewById(R.id.btn_add);
 btn_minus = findViewById(R.id.btn_minus);
 btn_point = findViewById(R.id.btn_point);
 btn_del =findViewById(R.id.btn_del);
 btn_equal = findViewById(R.id.btn_equal);
 btn_clean = findViewById(R.id.btn_clean);

 textView = findViewById(R.id.textView);

 btn_0.setOnClickListener(this); //设置按钮的点击事件
 btn_1.setOnClickListener(this);
 btn_2.setOnClickListener(this);
 btn_3.setOnClickListener(this);
 btn_4.setOnClickListener(this);
 btn_5.setOnClickListener(this);
 btn_6.setOnClickListener(this);
 btn_7.setOnClickListener(this);
 btn_8.setOnClickListener(this);
 btn_9.setOnClickListener(this);
 btn_minus.setOnClickListener(this);
 btn_multiply.setOnClickListener(this);
 btn_del.setOnClickListener(this);
 btn_divide.setOnClickListener(this);
 btn_point.setOnClickListener(this);
 btn_add.setOnClickListener(this);
 btn_equal.setOnClickListener(this);
 btn_clean.setOnClickListener(this);
 }

 public void onClick(View v) {
 String str = textView.getText().toString();
 switch(v.getId ()){
 case R.id.btn_0:
 case R.id.btn_1:
 case R.id.btn_2:
 case R.id.btn_3:
 case R.id.btn_4:
 case R.id.btn_5:
 case R.id.btn_6:
 case R.id.btn_7:
 case R.id.btn_8:
 case R.id.btn_9:
 case R.id.btn_point:
 if(clear_flag){
  clear_flag=false;
  str="";
  textView.setText ("");
 }
 textView.setText(str ((Button)v).getText ());
 break;

 case R.id.btn_add:
 case R.id.btn_minus:
 case R.id.btn_multiply:
 case R.id.btn_divide:
 if(clear_flag){
  clear_flag=false;
  textView.setText("");
 }
 textView.setText(str " " ((Button)v).getText() " ");
 break;
 case R.id.btn_del:
 if(clear_flag){
  clear_flag=false;
  textView.setText ("");
 }else if (str != null && !str.equals ("")){
  textView.setText(str.substring(0,str.length()-1)); //删除一个字符
 }
 break;
 case R.id.btn_clean:
 clear_flag=false;
 str = "";
 textView.setText(""); //清空文本内容
 break;
 case R.id.btn_equal:
 getResult(); //获取结果
 break;
 }
 }

 private void getResult() {  //算法
 String s = textView.getText().toString();
 if(s == null || s.equals ("")){
 return;
 }
 if (!s.contains ("")){
 return;
 }
 if (clear_flag){
 clear_flag=false;
 return;
 }
 clear_flag=true;

 String str1 = s.substring(0,s.indexOf(" "));  // 获取到运算符前面的字符
 String str_y = s.substring(s.indexOf(" ") 1,s.indexOf(" ") 2); //获取到运算符
 String str2 = s.substring(s.indexOf(" ")  3);  //获取到运算符后面的字符

 double result = 0;
 if (!str1.equals ("") && !str2.equals ("")){
 double num1 = Double.parseDouble(str1); //将str1、str2强制转化为double类型
 double num2 = Double.parseDouble(str2);

 if (str_y.equals (" ")){
 result = num1   num2;
 }else if (str_y.equals ("-")){
 result = num1 - num2;
 }else if (str_y.equals ("÷")){
 if (num2 == 0){
  result = 0;
 }else {
  result = num1/num2;
 }
 }else if (str_y.equals ("*")){
 result = num1*num2;
 }
 if (!str1.contains (".") && !str2.contains (".") && !s.equals ("÷")){
 int k = (int) result; //强制转换
 textView.setText (k);
 }else{
 textView.setText (result "");
 }
 }else if (!str1.equals ("") && str2.equals ("")){
 textView.setText (s);
 }else if (str1.equals ("") && !str2.equals ("")){
 double num2 = Double.parseDouble(str2);
 if (s.equals (" ")){
 result = 0   num2;
 }else if (s.equals("-")){
 result = 0 - num2;
 }else if (s.equals("×")){
 result = 0;
 }else if (s.equals("÷")){
 result = 0;
 }
 if (!str2.contains (".")) {
 int r = (int) result;
 textView.setText (r   "");
 } else {
 textView.setText (result   "");
 }
 } else {
 textView.setText ("");
 }
 }
}