Android开发应用案例——简易计算器（附完整源码）

Posted 2023-03-30 白天数糖晚上数羊

Android开发-AS学习（一）

Android开发-AS学习（二）

使用android studio开发简易计算器app（完整源码可在博主资源中自行下载）

最终效果：

开发步骤：

1. 创建一个名为calculator的新项目

2. 编写代码

项目目录

MyTextView文件

package com.example.calculator.my_control;

import android.content.Context;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.util.AttributeSet;


import androidx.annotation.NonNull;
import androidx.annotation.Nullable;


/*
自定义组件：带有边框的标签
 */
public class MyTextView extends androidx.appcompat.widget.AppCompatTextView 
    Paint paint = new Paint();//创建一个paint对象

    public MyTextView(@NonNull Context context, @Nullable AttributeSet attrs) 
        super(context, attrs);//构造函数
    

    @Override//重写方法
    protected void onDraw(Canvas canvas)
        super.onDraw(canvas);
        paint.setColor(Color.BLACK);//设置paint的颜色

        //绘制边框
        canvas.drawLine(0,0,this.getWidth(),0,paint);//绘制上方的边框
        canvas.drawLine(0,this.getHeight()-1,this.getWidth(),this.getHeight()-1,paint);//绘制下方的边框(因为会被遮挡，所以需要-1）
        canvas.drawLine(0,0,0,this.getHeight(),paint);//绘制左边的边框
        canvas.drawLine(this.getWidth()-1,0,this.getWidth()-1,this.getHeight(),paint);//绘制右边的边框(因为会被遮挡，所以需要-1）

    

MainActivity文件

package com.example.calculator;

import androidx.appcompat.app.AppCompatActivity;
import androidx.databinding.DataBindingUtil;
import androidx.lifecycle.Observer;
import androidx.lifecycle.ViewModelProvider;

import android.database.DatabaseUtils;
import android.os.Bundle;
import android.view.View;

import com.example.calculator.databinding.ActivityMainBinding;

public class MainActivity extends AppCompatActivity 

    private ActivityMainBinding binding;//组件存储类

    private MyViewModel myViewModel;//数据模型

    @Override
    protected void onCreate(Bundle savedInstanceState) 
        super.onCreate(savedInstanceState);
        binding = DataBindingUtil.setContentView(this,R.layout.activity_main);//获取所有控件
        myViewModel = new ViewModelProvider(this,new ViewModelProvider.NewInstanceFactory()).get(MyViewModel.class);//获取数据模型



        //事件监听
        myViewModel.getMainNum().observe(this, new Observer<String>() 
            @Override
            public void onChanged(String s) //监听 mainNum数据发生改变的监听
                binding.myTextView.setText(myViewModel.getMainNum().getValue());//让 myTextView显示mainNum的数值，也就是计算器中的输入框显示数值


                if (myViewModel.sign2.equals(""))
                    if (myViewModel.sign1.equals(""))
                        binding.textView2.setText(myViewModel.getMainNum().getValue());//让 textView显示式子，也就是输入框上面的小框显示计算式
                    
                    else //如果是像a + b这种形式的式子时
                        binding.textView2.setText(myViewModel.num[0] + myViewModel.sign1 + myViewModel.getMainNum().getValue());
                    
                
                else //如果是像a+b*c这种形式的式子的时候
                    binding.textView2.setText(myViewModel.num[0] + myViewModel.sign1 + myViewModel.num[1] + myViewModel.sign2 + myViewModel.getMainNum().getValue());
                


            
        );
        binding.button0.setOnClickListener(new View.OnClickListener() 
            @Override
            public void onClick(View view) 
                myViewModel.setMainNum("0");
            
        );
        binding.button1.setOnClickListener(new View.OnClickListener() 
            @Override
            public void onClick(View view) 
                myViewModel.setMainNum("1");
            
        );
        binding.button2.setOnClickListener(new View.OnClickListener() 
            @Override
            public void onClick(View view) 
                myViewModel.setMainNum("2");
            
        );
        binding.button3.setOnClickListener(new View.OnClickListener() 
            @Override
            public void onClick(View view) 
                myViewModel.setMainNum("3");
            
        );
        binding.button4.setOnClickListener(new View.OnClickListener() 
            @Override
            public void onClick(View view) 
                myViewModel.setMainNum("4");
            
        );
        binding.button5.setOnClickListener(new View.OnClickListener() 
            @Override
            public void onClick(View view) 
                myViewModel.setMainNum("5");
            
        );
        binding.button6.setOnClickListener(new View.OnClickListener() 
            @Override
            public void onClick(View view) 
                myViewModel.setMainNum("6");
            
        );
        binding.button7.setOnClickListener(new View.OnClickListener() 
            @Override
            public void onClick(View view) 
                myViewModel.setMainNum("7");
            
        );
        binding.button8.setOnClickListener(new View.OnClickListener() 
            @Override
            public void onClick(View view) 
                myViewModel.setMainNum("8");
            
        );
        binding.button9.setOnClickListener(new View.OnClickListener() 
            @Override
            public void onClick(View view) 
                myViewModel.setMainNum("9");
            
        );
        //给小数点按钮的监听
        binding.button15.setOnClickListener(new View.OnClickListener() 
            @Override
            public void onClick(View view) 
                if (!myViewModel.havePoint)
                    myViewModel.getMainNum().setValue(myViewModel.getMainNum().getValue()+".");
                    myViewModel.havePoint=true;
                
            
        );
        //给加号按钮的监听
        binding.button11.setOnClickListener(new View.OnClickListener() 
            @Override
            public void onClick(View view) 
                if (myViewModel.sign1.equals(""))
                    myViewModel.sign1="+";
                    myViewModel.num[0] = myViewModel.getMainNum().getValue();
                    myViewModel.getMainNum().setValue("0");
                    myViewModel.havePoint=false;
                
                else if (myViewModel.sign2.equals(""))//如果是像a+b这种形式的式子时
                    myViewModel.num[0] = myViewModel.mainNumWithNum_0_Tocal();
                    myViewModel.sign1="+";
                    myViewModel.getMainNum().setValue("0");
                    myViewModel.havePoint = false;

                
                else //如果是像a+b*c这种形式的式子时
                    myViewModel.getMainNum().setValue(myViewModel.mainNumWith_Num_1_Tocal());
                    myViewModel.sign2="";
                    myViewModel.num[1] = "";
                    myViewModel.num[0] = myViewModel.mainNumWithNum_0_Tocal();
                    myViewModel.sign1 = "+";
                    myViewModel.getMainNum().setValue("0");
                    myViewModel.havePoint = false;
                
            
        );
        //给减号设置监听
        binding.button12.setOnClickListener(new View.OnClickListener() 
            @Override
            public void onClick(View view) 
                if (myViewModel.sign1.equals(""))
                    myViewModel.sign1="-";
                    myViewModel.num[0] = myViewModel.getMainNum().getValue();
                    myViewModel.getMainNum().setValue("0");
                    myViewModel.havePoint=false;
                
                else if (myViewModel.sign2.equals(""))//如果是像a-b这种形式的式子时
                    myViewModel.num[0] = myViewModel.mainNumWithNum_0_Tocal();
                    myViewModel.sign1="-";
                    myViewModel.getMainNum().setValue("0");
                    myViewModel.havePoint = false;

                
                else //如果是像a-b*c这种形式的式子时
                    myViewModel.getMainNum().setValue(myViewModel.mainNumWith_Num_1_Tocal());
                    myViewModel.sign2="";
                    myViewModel.num[1] = "";
                    myViewModel.num[0] = myViewModel.mainNumWithNum_0_Tocal();
                    myViewModel.sign1 = "-";
                    myViewModel.getMainNum().setValue("0");
                    myViewModel.havePoint = false;
                
            
        );
        //给乘号设置监听
        binding.button13.setOnClickListener(new View.OnClickListener() 
            @Override
            public void onClick(View view) 
                if (myViewModel.sign1.equals(""))
                    myViewModel.sign1 = "*";
                    myViewModel.num[0] = myViewModel.getMainNum().getValue();
                    myViewModel.getMainNum().setValue("0");
                    myViewModel.havePoint = false;
                
                else if (myViewModel.sign2.equals(""))
                    if (myViewModel.sign1.equals("*") || myViewModel.sign1.equals("/"))//按顺序进行计算
                        myViewModel.num[0] = myViewModel.mainNumWithNum_0_Tocal();
                        myViewModel.sign1="*";
                        myViewModel.getMainNum().setValue("0");
                        myViewModel.havePoint = false;
                    
                    else //如果sign1是减号或者加号时
                        myViewModel.num[1] = myViewModel.getMainNum().getValue();
                        myViewModel.sign2 = "*";
                        myViewModel.getMainNum().setValue("0");
                        myViewModel.havePoint = false;

                    
                
                else //如果像a+b*c形式的式子时
                    myViewModel.num[1] = myViewModel.mainNumWith_Num_1_Tocal();
                    myViewModel.sign2 = "*";
                    myViewModel.getMainNum().setValue("0");
                    myViewModel.havePoint = false;
                
            
        );
        //给除号设置监听
        binding.button14.setOnClickListener(new View.OnClickListener() 
            @Override
            public void onClick(View view) 
                if (myViewModel.sign1.equals(""))
                    myViewModel.sign1 = "/";
                    myViewModel.num[0] = myViewModel.getMainNum().getValue();
                    myViewModel.getMainNum().setValue("0");
                    myViewModel.havePoint = false;
                
                else if (myViewModel.sign2.equals(""))
                    if (myViewModel.sign1.equals("*") || myViewModel.sign1.equals("/"))//按顺序进行计算
                        myViewModel.num[0] = myViewModel.mainNumWithNum_0_Tocal();
                        myViewModel.sign1="/";
                        myViewModel.getMainNum().setValue("0");
                        myViewModel.havePoint = false;
                    
                    else //如果sign1是减号或者加号时
                        myViewModel.num[1] = myViewModel.getMainNum().getValue();
                        myViewModel.sign2 = "/";
                        myViewModel.getMainNum().setValue("0");
                        myViewModel.havePoint = false;

                    
                
                else //如果像a+b/c形式的式子时
                    myViewModel.num[1] = myViewModel.mainNumWith_Num_1_Tocal();
                    myViewModel.sign2 = "/";
                    myViewModel.getMainNum().setValue("0");
                    myViewModel.havePoint = false;
                
            
        );
        //给 清空 设置监听
        binding.button17.setOnClickListener(new View.OnClickListener() 
            @Override
            public void onClick(View view) 
                myViewModel.sign2 = "";
                myViewModel.num[1] = "";
                myViewModel.sign1 = "";
                myViewModel.num[0] = "";
                myViewModel.getMainNum().setValue("0");
                myViewModel.havePoint = false;
            
        );
        //给 计算按钮 设置监听
        binding.button16.setOnClickListener(new View.OnClickListener() 
            @Override
            public void onClick(View view) 
                if (myViewModel.sign2.equals(""))
                    if (!myViewModel.sign1.equals(""))
                        myViewModel.getMainNum().setValue(myViewModel.mainNumWithNum_0_Tocal());
                        if (myViewModel.getMainNum().getValue().contains("."))//判断是否包含小数点
                            myViewModel.havePoint = true;
                        
                        else myViewModel.havePoint = false;
                        myViewModel.num[0]="";
                        myViewModel.sign1 = "";
                    
                
                else //如果是像 a+b*c 这种形式的式子时
                    myViewModel.getMainNum().setValue(myViewModel.mainNumWith_Num_1_Tocal());
                    myViewModel.num[1] = "";
                    myViewModel.sign2 = "";
                    myViewModel.getMainNum().setValue(myViewModel.mainNumWithNum_0_Tocal());
                    if (myViewModel.getMainNum().getValue().contains("."))//判断是否包含小数点
                        myViewModel.havePoint = true;
                    
                    else myViewModel.havePoint = false;
                    myViewModel.num[0]="";
                    myViewModel.sign1 = "";
                
                binding.textView2.setText(myViewModel.num[0] + myViewModel.sign1 + myViewModel.getMainNum().getValue());
            
        );
        //给 退格按钮 设置监听
        binding.imageButton.setOnClickListener(new View.OnClickListener() 
            @Override
            public void onClick(View view) 
                if (!myViewModel.getMainNum().getValue().equals("0"))
                    myViewModel.getMainNum().setValue(myViewModel.getMainNum().getValue().substring(0,myViewModel.getMainNum().getValue().length()-1));//不为空，长度减1
                    if (myViewModel.getMainNum().getValue().equals(""))
                        myViewModel.getMainNum().setValue("0");//如果为空，将其设为0
                    
                
            
        );



    

MyViewModel

package com.example.calculator;

import androidx.lifecycle.MutableLiveData;
import androidx.lifecycle.ViewModel;

//用来存储一些数据模型
public class MyViewModel extends ViewModel 
    private MutableLiveData<String> mainNum;//主数值（用户正在操作的数）
    public boolean havePoint =false;//用于记录主数值中是否包含小数点
    public String sign1 = "",sign2 = "";//用于存储运算符号
    public String num[]="","";//用于存储参与计算的数值

    public MutableLiveData<String> getMainNum()
        if (mainNum == null)
            mainNum = new MutableLiveData<>();
            mainNum.setValue("0");
        
        return mainNum;
    

    public void setMainNum(String n )
        if (mainNum.getValue().equals("0"))
            mainNum.setValue(n);
        
        else 
            mainNum.setValue(mainNum.getValue() + n);
        
    


    public String mainNumWithNum_0_Tocal()
        String value = "0";
        if (mainNum.getValue().contains(".") || num[0].contains(".")) //如果两个数的其中一个有小数点的运算
            switch (sign1)
                case "+":
                    value = String.valueOf(Double.valueOf(num[0]) + Double.valueOf(mainNum.getValue()));
                    break;
                case "-":
                    value = String.valueOf(Double.valueOf(num[0]) - Double.valueOf(mainNum.getValue()));
                    break;
                case "*":
                    value = String.valueOf(Double.valueOf(num[0]) * Double.valueOf(mainNum.getValue()));
                    break;
                case "/":
                    if (mainNum.getValue().equals("0"))
                        mainNum.setValue("1");
                    
                    value = String.valueOf(Double.valueOf(num[0]) / Double.valueOf(mainNum.getValue()));

            
        
        else 
            switch (sign1)//如果没有小数点则为整数运算
                case "+":
                    value = String.valueOf(Integer.valueOf(num[0]) + Integer.valueOf(mainNum.getValue()));
                    break;
                case "-":
                    value = String.valueOf(Integer.valueOf(num[0]) - Integer.valueOf(mainNum.getValue()));
                    break;
                case "*":
                    value = String.valueOf(Integer.valueOf(num[0]) * Integer.valueOf(mainNum.getValue()));
                    break;
                case "/"://除号依旧为小数运算方式
                    if (mainNum.getValue().equals("0"))
                        mainNum.setValue("1");
                    
                    value = String.valueOf(Double.valueOf(num[0]) / Double.valueOf(mainNum.getValue()));
            
        
        return value;
    

    public String mainNumWith_Num_1_Tocal()
        String value = "0";
        if (mainNum.getValue().contains(".") || num[0].contains(".")) //如果两个数的其中一个有小数点的运算
            switch (sign2)
                case "*":
                    value = String.valueOf(Double.valueOf(num[1]) * Double.valueOf(mainNum.getValue()));
                    break;
                case "/":
                    if (mainNum.getValue().equals("0"))
                        mainNum.setValue("1");
                    
                    value = String.valueOf(Double.valueOf(num[1]) / Double.valueOf(mainNum.getValue()));

            
        
        else 
            switch (sign2)//如果没有小数点则为整数运算
                case "*":
                    value = String.valueOf(Integer.valueOf(num[1]) * Integer.valueOf(mainNum.getValue()));
                    break;
                case "/"://除号依旧为小数运算方式
                    if (mainNum.getValue().equals("0"))
                        mainNum.setValue("1");
                    
                    value = String.valueOf(Double.valueOf(num[1]) / Double.valueOf(mainNum.getValue()));
            
        
        return value;
    

activity_main.xml

<?xml version="1.0" encoding="utf-8"?>
<layout 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">

    <data>


    </data>

    <androidx.constraintlayout.widget.ConstraintLayout
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        tools:context=".MainActivity">

        <com.example.calculator.my_control.MyTextView
            android:id="@+id/myTextView"
            android:layout_width="0dp"
            android:layout_height="wrap_content"
            android:padding="1dp"
            android:text="@string/_0"
            android:textAlignment="textEnd"
            android:textSize="65sp"
            app:layout_constraintBottom_toTopOf="@+id/guideline5"
            app:layout_constraintEnd_toStartOf="@+id/guideline2"
            app:layout_constraintStart_toStartOf="@+id/guideline3"
            app:layout_constraintTop_toTopOf="@+id/guideline4" />

        <androidx.constraintlayout.widget.Guideline
            android:id="@+id/guideline2"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:orientation="vertical"
            app:layout_constraintGuide_begin="375dp" />

        <androidx.constraintlayout.widget.Guideline
            android:id="@+id/guideline3"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:orientation="vertical"
            app:layout_constraintGuide_begin="16dp" />

        <androidx.constraintlayout.widget.Guideline
            android:id="@+id/guideline4"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:orientation="horizontal"
            app:layout_constraintGuide_begin="40dp" />

        <androidx.constraintlayout.widget.Guideline
            android:id="@+id/guideline5"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:orientation="horizontal"
            app:layout_constraintGuide_begin="136dp" />

        <TextView
            android:id="@+id/textView"
            android:layout_width="0dp"
            android:layout_height="0dp"
            android:text="TextView"
            app:layout_constraintBottom_toTopOf="@+id/myTextView"
            app:layout_constraintEnd_toStartOf="@+id/guideline2"
            app:layout_constraintStart_toStartOf="@+id/guideline3" />

        <TextView
            android:id="@+id/textView2"
            android:layout_width="0dp"
            android:layout_height="wrap_content"
            android:text="@string/_0"
            android:textAlignment="textEnd"
            android:textSize="24sp"
            app:layout_constraintBottom_toTopOf="@+id/myTextView"
            app:layout_constraintEnd_toStartOf="@+id/guideline2"
            app:layout_constraintStart_toStartOf="@+id/guideline3" />

        <androidx.gridlayout.widget.GridLayout
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            app:layout_constraintBottom_toBottomOf="parent"
            app:layout_constraintEnd_toEndOf="parent"
            app:layout_constraintHorizontal_bias="0.271"
            app:layout_constraintStart_toStartOf="parent"
            app:layout_constraintTop_toBottomOf="@+id/myTextView"
            app:layout_constraintVertical_bias="0.532">

            <Button
                android:id="@+id/button2"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:insetLeft="5dp"
                android:insetRight="5dp"
                android:text="@string/_2"
                android:textSize="20sp"
                app:layout_column="1"
                app:layout_row="2" />

            <Button
                android:id="@+id/button3"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:insetLeft="5dp"
                android:insetRight="5dp"
                android:text="@string/_3"
                android:textSize="20sp"
                app:layout_column="2"
                app:layout_row="2" />

            <Button
                android:id="@+id/button4"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:insetLeft="5dp"
                android:insetRight="5dp"
                android:text="@string/_4"
                android:textSize="20sp"
                app:layout_column="0"
                app:layout_row="1" />

            <Button
                android:id="@+id/button5"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:insetLeft="5dp"
                android:insetRight="5dp"
                android:text="@string/_5"
                android:textSize="20sp"
                app:layout_column="1"
                app:layout_row="1" />

            <Button
                android:id="@+id/button6"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:insetLeft="5dp"
                android:insetRight="5dp"
                android:text="@string/_6"
                android:textSize="20sp"
                app:layout_column="2"
                app:layout_row="1" />

            <Button
                android:id="@+id/button7"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:insetLeft="5dp"
                android:insetRight="5dp"
                android:text="@string/_7"
                android:textSize="20sp"
                app:layout_column="0"
                app:layout_row="0" />

            <Button
                android:id="@+id/button8"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:insetLeft="5dp"
                android:insetRight="5dp"
                android:text="@string/_8"
                android:textSize="20sp"
                app:layout_column="1"
                app:layout_row="0" />

            <Button
                android:id="@+id/button9"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:insetLeft="5dp"
                android:insetRight="5dp"
                android:text="@string/_9"
                android:textSize="20sp"
                app:layout_column="2"
                app:layout_row="0" />

            <Button
                android:id="@+id/button0"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:insetLeft="5dp"
                android:insetRight="5dp"
                android:text="@string/_0"
                android:textSize="20sp"
                app:layout_column="1"
                app:layout_row="3" />

            <Button
                android:id="@+id/button11"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:insetLeft="5dp"
                android:insetRight="5dp"
                android:text="@string/jia"
                android:textSize="20sp"
                app:layout_column="3"
                app:layout_row="0" />

            <Button
                android:id="@+id/button12"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:insetLeft="5dp"
                android:insetRight="5dp"
                android:text="@string/jian"
                android:textSize="20sp"
                app:layout_column="3"
                app:layout_row="1" />

            <Button
                android:id="@+id/button13"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:insetLeft="5dp"
                android:insetRight="5dp"
                android:text="@string/cheng"
                android:textSize="20sp"
                app:layout_column="3"
                app:layout_row="2" />

            <Button
                android:id="@+id/button14"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:insetLeft="5dp"
                android:insetRight="5dp"
                android:text="@string/chu"
                android:textSize="20sp"
                app:layout_column="3"
                app:layout_row="3" />

            <Button
                android:id="@+id/button15"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:insetLeft="5dp"
                android:insetRight="5dp"
                android:text="@string/point"
                android:textSize="20sp"
                app:layout_column="2"
                app:layout_row="3" />

            <Button
                android:id="@+id/button16"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:insetLeft="5dp"
                android:insetRight="5dp"
                android:text="@string/jisuan"
                android:textSize="20sp"
                app:layout_column="0"
                app:layout_row="4" />

            <Button
                android:id="@+id/button1"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:insetLeft="5dp"
                android:insetRight="5dp"
                android:text="@string/_1"
                android:textSize="20sp"
                app:layout_column="0"
                app:layout_row="2" />

            <Button
                android:id="@+id/button17"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:insetLeft="5dp"
                android:insetRight="5dp"
                android:text="@string/qingkong"
                android:textSize="20sp"
                app:layout_column="0"
                app:layout_row="3" />

            <ImageButton
                android:id="@+id/imageButton"
                android:layout_width="86dp"
                android:layout_height="55dp"
                app:layout_column="3"
                app:layout_row="4"
                app:srcCompat="@drawable/ic_baseline_backspace_24" />
        </androidx.gridlayout.widget.GridLayout>

        <androidx.gridlayout.widget.GridLayout
            android:layout_width="wrap_content"
            android:layout_height="match_parent">

        </androidx.gridlayout.widget.GridLayout>

    </androidx.constraintlayout.widget.ConstraintLayout>
</layout>

补充：

1、在drawable中引入backspace矢量图

2、在build.gradle文件中添加dataBindingenabled true代码