package com.example.chapter03;

import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;

import androidx.annotation.Nullable;
import androidx.appcompat.app.AppCompatActivity;

import com.example.chapter03.R;

public class jisuanqi extends AppCompatActivity {
    private EditText num1;
    private EditText num2;
    private EditText mathlabel;
    private EditText num3;
    private Button btn;
    @Override
    protected void onCreate(@Nullable Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.active_jisuanqi);
        num1=findViewById(R.id.numberEdittext1);
        num2=findViewById(R.id.numberEdittext2);
        mathlabel=findViewById(R.id.numberEdittext3);
        num3=findViewById(R.id.numterEdittext4);
        btn=findViewById(R.id.button);

        btn.setOnLongClickListener(new View.OnLongClickListener() {
            @Override
            public boolean onLongClick(View view) {
                Double numthree=null;
                double numone=0;
                double numtwo=0;
                String mathlabelone=null;
                try {
                     numone=Double.parseDouble(num1.getText().toString());
                     numtwo=Double.parseDouble(num2.getText().toString());
                     mathlabelone=mathlabel.getText().toString();
                }catch (NumberFormatException e){
                    num3.setText(R.string.hello);
                    return true;

                }
                if (mathlabelone.equals("+")){
                    numthree=numone+numtwo;
                }
                else if (mathlabelone.equals("-")){
                    numthree=numone-numtwo;
                }
                else if (mathlabelone.equals("*")){
                    numthree=numone*numtwo;
                }
                else if (mathlabelone.equals("/")){
                    numthree=numone/numtwo;
                }

                num3.setText(numthree.toString());
                return true;
            }
        });



    }
}

<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".MainActivity2">

    <TextView
        android:id="@+id/textView"
        android:layout_width="66dp"
        android:layout_height="33dp"
        android:layout_marginStart="60dp"
        android:layout_marginTop="84dp"
        android:text="计算数1"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent" />

    <EditText
        android:id="@+id/numberEdittext1"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginStart="40dp"
        android:layout_marginTop="72dp"
        android:ems="10"
        android:inputType="textPersonName"
        android:text=""
        app:layout_constraintStart_toEndOf="@+id/textView"
        app:layout_constraintTop_toTopOf="parent" />

    <TextView
        android:id="@+id/textView2"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginStart="60dp"
        android:layout_marginTop="32dp"
        android:text="计算数2"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toBottomOf="@+id/textView" />

    <EditText
        android:id="@+id/numberEdittext2"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginStart="56dp"
        android:layout_marginTop="20dp"
        android:ems="10"
        android:inputType="textPersonName"
        android:text=""
        app:layout_constraintStart_toEndOf="@+id/textView2"
        app:layout_constraintTop_toBottomOf="@+id/numberEdittext1" />

    <TextView
        android:id="@+id/textView3"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginTop="104dp"
        android:text="运算符"
        app:layout_constraintTop_toBottomOf="@+id/textView"
        tools:layout_editor_absoluteX="58dp" />

    <EditText
        android:id="@+id/numberEdittext3"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginStart="64dp"
        android:layout_marginTop="88dp"
        android:ems="10"
        android:inputType="textPersonName"
        android:text=""
        app:layout_constraintStart_toEndOf="@+id/textView3"
        app:layout_constraintTop_toBottomOf="@+id/numberEdittext1" />

    <Button
        android:id="@+id/button"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginStart="161dp"
        android:layout_marginTop="200dp"
        android:text="计算"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toBottomOf="@+id/numberEdittext1" />

    <TextView
        android:id="@+id/textView4"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginStart="60dp"
        android:layout_marginTop="312dp"
        android:text="结果"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toBottomOf="@+id/textView" />

    <EditText
        android:id="@+id/numterEdittext4"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginStart="72dp"
        android:layout_marginTop="292dp"
        android:ems="10"
        android:inputType="textPersonName"
        android:minHeight="48dp"
        android:text=""
        app:layout_constraintStart_toEndOf="@+id/textView4"
        app:layout_constraintTop_toBottomOf="@+id/numberEdittext1" />
</androidx.constraintlayout.widget.ConstraintLayout>

<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".MainActivity2">

    <TextView
        android:id="@+id/textView"
        android:layout_width="66dp"
        android:layout_height="33dp"
        android:layout_marginStart="60dp"
        android:layout_marginTop="84dp"
        android:text="计算数1"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent" />

    <EditText
        android:id="@+id/numberEdittext1"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginStart="40dp"
        android:layout_marginTop="72dp"
        android:ems="10"
        android:inputType="textPersonName"
        android:text=""
        app:layout_constraintStart_toEndOf="@+id/textView"
        app:layout_constraintTop_toTopOf="parent" />

    <TextView
        android:id="@+id/textView2"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginStart="60dp"
        android:layout_marginTop="32dp"
        android:text="计算数2"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toBottomOf="@+id/textView" />

    <EditText
        android:id="@+id/numberEdittext2"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginStart="56dp"
        android:layout_marginTop="20dp"
        android:ems="10"
        android:inputType="textPersonName"
        android:text=""
        app:layout_constraintStart_toEndOf="@+id/textView2"
        app:layout_constraintTop_toBottomOf="@+id/numberEdittext1" />

    <TextView
        android:id="@+id/textView3"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginTop="104dp"
        android:text="运算符"
        app:layout_constraintTop_toBottomOf="@+id/textView"
        tools:layout_editor_absoluteX="58dp" />

    <EditText
        android:id="@+id/numberEdittext3"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginStart="64dp"
        android:layout_marginTop="88dp"
        android:ems="10"
        android:inputType="textPersonName"
        android:text=""
        app:layout_constraintStart_toEndOf="@+id/textView3"
        app:layout_constraintTop_toBottomOf="@+id/numberEdittext1" />

    <Button
        android:id="@+id/button"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginStart="161dp"
        android:layout_marginTop="200dp"
        android:text="计算"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toBottomOf="@+id/numberEdittext1" />

    <TextView
        android:id="@+id/textView4"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginStart="60dp"
        android:layout_marginTop="312dp"
        android:text="结果"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toBottomOf="@+id/textView" />

    <EditText
        android:id="@+id/numterEdittext4"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginStart="72dp"
        android:layout_marginTop="292dp"
        android:ems="10"
        android:inputType="textPersonName"
        android:minHeight="48dp"
        android:text=""
        app:layout_constraintStart_toEndOf="@+id/textView4"
        app:layout_constraintTop_toBottomOf="@+id/numberEdittext1" />
</androidx.constraintlayout.widget.ConstraintLayout>