帮我用androidStudio写一个简单计算器页面和代码

好的，下面是一个简单的计算器页面和代码示例：

1. 首先，在Android Studio中创建一个新项目，选择Empty Activity。

2. 打开activity_main.xml文件，将以下代码复制并粘贴到文件中：

<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.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:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".MainActivity">

    <TextView
        android:id="@+id/resultTextView"
        android:layout_width="0dp"
        android:layout_height="wrap_content"
        android:layout_marginTop="16dp"
        android:layout_marginBottom="16dp"
        android:text="0"
        android:textAlignment="center"
        android:textSize="30sp"
        app:layout_constraintBottom_toTopOf="@+id/guideline2"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintHorizontal_bias="0.0"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="@+id/guideline"
        app:layout_constraintVertical_bias="0.0" />

    <Button
        android:id="@+id/clearButton"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginStart="16dp"
        android:layout_marginTop="16dp"
        android:layout_marginEnd="16dp"
        android:backgroundTint="#FF0000"
        android:text="C"
        app:layout_constraintEnd_toStartOf="@+id/divideButton"
        app:layout_constraintHorizontal_bias="0.5"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toBottomOf="@+id/resultTextView" />

    <Button
        android:id="@+id/divideButton"
        android:layout_width="0dp"
        android:layout_height="wrap_content"
        android:layout_marginStart="8dp"
        android:layout_marginTop="16dp"
        android:layout_marginEnd="8dp"
        android:text="/"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintHorizontal_bias="0.5"
        app:layout_constraintStart_toEndOf="@+id/clearButton"
        app:layout_constraintTop_toBottomOf="@+id/resultTextView" />

    <Button
        android:id="@+id/multiplyButton"
        android:layout_width="0dp"
        android:layout_height="wrap_content"
        android:layout_marginStart="8dp"
        android:layout_marginTop="16dp"
        android:layout_marginEnd="8dp"
        android:text="*"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintHorizontal_bias="0.5"
        app:layout_constraintStart_toEndOf="@+id/divideButton"
        app:layout_constraintTop_toBottomOf="@+id/resultTextView" />

    <Button
        android:id="@+id/minusButton"
        android:layout_width="0dp"
        android:layout_height="wrap_content"
        android:layout_marginStart="8dp"
        android:layout_marginTop="16dp"
        android:layout_marginEnd="8dp"
        android:text="-"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintHorizontal_bias="0.5"
        app:layout_constraintStart_toEndOf="@+id/multiplyButton"
        app:layout_constraintTop_toBottomOf="@+id/resultTextView" />

    <Button
        android:id="@+id/plusButton"
        android:layout_width="0dp"
        android:layout_height="wrap_content"
        android:layout_marginStart="8dp"
        android:layout_marginTop="16dp"
        android:layout_marginEnd="8dp"
        android:text="+"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintHorizontal_bias="0.5"
        app:layout_constraintStart_toEndOf="@+id/minusButton"
        app:layout_constraintTop_toBottomOf="@+id/resultTextView" />

    <Button
        android:id="@+id/equalButton"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginStart="16dp"
        android:layout_marginTop="16dp"
        android:layout_marginEnd="16dp"
        android:backgroundTint="#00FF00"
        android:text="="
        app:layout_constraintEnd_toStartOf="@+id/plusButton"
        app:layout_constraintHorizontal_bias="0.5"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toBottomOf="@+id/divideButton" />

    <Button
        android:id="@+id/dotButton"
        android:layout_width="0dp"
        android:layout_height="wrap_content"
        android:layout_marginStart="8dp"
        android:layout_marginTop="16dp"
        android:layout_marginEnd="8dp"
        android:text="."
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintHorizontal_bias="0.5"
        app:layout_constraintStart_toEndOf="@+id/equalButton"
        app:layout_constraintTop_toBottomOf="@+id/divideButton" />

    <Button
        android:id="@+id/zeroButton"
        android:layout_width="0dp"
        android:layout_height="wrap_content"
        android:layout_marginStart="8dp"
        android:layout_marginTop="16dp"
        android:layout_marginEnd="8dp"
        android:text="0"
        app:layout_constraintEnd_toStartOf="@+id/dotButton"
        app:layout_constraintHorizontal_bias="0.5"
        app:layout_constraintStart_toEndOf="@+id/equalButton"
        app:layout_constraintTop_toBottomOf="@+id/divideButton" />

    <Button
        android:id="@+id/oneButton"
        android:layout_width="0dp"
        android:layout_height="wrap_content"
        android:layout_marginStart="8dp"
        android:layout_marginTop="16dp"
        android:layout_marginEnd="8dp"
        android:text="1"
        app:layout_constraintEnd_toStartOf="@+id/twoButton"
        app:layout_constraintHorizontal_bias="0.5"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toBottomOf="@+id/equalButton" />

    <Button
        android:id="@+id/twoButton"
        android:layout_width="0dp"
        android:layout_height="wrap_content"
        android:layout_marginStart="8dp"
        android:layout_marginTop="16dp"
        android:layout_marginEnd="8dp"
        android:text="2"
        app:layout_constraintEnd_toStartOf="@+id/threeButton"
        app:layout_constraintHorizontal_bias="0.5"
        app:layout_constraintStart_toEndOf="@+id/oneButton"
        app:layout_constraintTop_toBottomOf="@+id/equalButton" />

    <Button
        android:id="@+id/threeButton"
        android:layout_width="0dp"
        android:layout_height="wrap_content"
        android:layout_marginStart="8dp"
        android:layout_marginTop="16dp"
        android:layout_marginEnd="8dp"
        android:text="3"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintHorizontal_bias="0.5"
        app:layout_constraintStart_toEndOf="@+id/twoButton"
        app:layout_constraintTop_toBottomOf="@+id/equalButton" />

    <Button
        android:id="@+id/fourButton"
        android:layout_width="0dp"
        android:layout_height="wrap_content"
        android:layout_marginStart="8dp"
        android:layout_marginTop="16dp"
        android:layout_marginEnd="8dp"
        android:text="4"
        app:layout_constraintEnd_toStartOf="@+id/fiveButton"
        app:layout_constraintHorizontal_bias="0.5"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toBottomOf="@+id/oneButton" />

    <Button
        android:id="@+id/fiveButton"
        android:layout_width="0dp"
        android:layout_height="wrap_content"
        android:layout_marginStart="8dp"
        android:layout_marginTop="16dp"
        android:layout_marginEnd="8dp"
        android:text="5"
        app:layout_constraintEnd_toStartOf="@+id/sixButton"
        app:layout_constraintHorizontal_bias="0.5"
        app:layout_constraintStart_toEndOf="@+id/fourButton"
        app:layout_constraintTop_toBottomOf="@+id/twoButton" />

    <Button
        android:id="@+id/sixButton"
        android:layout_width="0dp"
        android:layout_height="wrap_content"
        android:layout_marginStart="8dp"
        android:layout_marginTop="16dp"
        android:layout_marginEnd="8dp"
        android:text="6"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintHorizontal_bias="0.5"
        app:layout_constraintStart_toEndOf="@+id/fiveButton"
        app:layout_constraintTop_toBottomOf="@+id/threeButton" />

    <Button
        android:id="@+id/sevenButton"
        android:layout_width="0dp"
        android:layout_height="wrap_content"
        android:layout_marginStart="8dp"
        android:layout_marginTop="16dp"
        android:layout_marginEnd="8dp"
        android:text="7"
        app:layout_constraintEnd_toStartOf="@+id/eightButton"
        app:layout_constraintHorizontal_bias="0.5"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toBottomOf="@+id/fourButton" />

    <Button
        android:id="@+id/eightButton"
        android:layout_width="0dp"
        android:layout_height="wrap_content"
        android:layout_marginStart="8dp"
        android:layout_marginTop="16dp"
        android:layout_marginEnd="8dp"
        android:text="8"
        app:layout_constraintEnd_toStartOf="@+id/nineButton"
        app:layout_constraintHorizontal_bias="0.5"
        app:layout_constraintStart_toEndOf="@+id/sevenButton"
        app:layout_constraintTop_toBottomOf="@+id/fiveButton" />

    <Button
        android:id="@+id/nineButton"
        android:layout_width="0dp"
        android:layout_height="wrap_content"
        android:layout_marginStart="8dp"
        android:layout_marginTop="16dp"
        android:layout_marginEnd="8dp"
        android:text="9"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintHorizontal_bias="0.5"
        app:layout_constraintStart_toEndOf="@+id/eightButton"
        app:layout_constraintTop_toBottomOf="@+id/sixButton" />

    <androidx.constraintlayout.widget.Guideline
        android:id="@+id/guideline"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:orientation="horizontal"
        app:layout_constraintGuide_begin="64dp" />

    <androidx.constraintlayout.widget.Guideline
        android:id="@+id/guideline2"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:orientation="horizontal"
        app:layout_constraintGuide_begin="312dp" />

</androidx.constraintlayout.widget.ConstraintLayout>

3. 打开MainActivity.java文件，将以下代码复制并粘贴到文件中：

import androidx.appcompat.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.TextView;

public class MainActivity extends AppCompatActivity {

    private TextView resultTextView;
    private String display = "";
    private double num1 = 0;
    private double num2 = 0;
    private char operation;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        resultTextView = findViewById(R.id.resultTextView);

        Button clearButton = findViewById(R.id.clearButton);
        clearButton.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                display = "";
                num1 = 0;
                num2 = 0;
                operation = ' ';
                resultTextView.setText("0");
            }
        });

        Button divideButton = findViewById(R.id.divideButton);
        divideButton.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                operation = '/';
                num1 = Double.parseDouble(display);
                display = "";
            }
        });

        Button multiplyButton = findViewById(R.id.multiplyButton);
        multiplyButton.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                operation = '*';
                num1 = Double.parseDouble(display);
                display = "";
            }
        });

        Button minusButton = findViewById(R.id.minusButton);
        minusButton.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                operation = '-';
                num1 = Double.parseDouble(display);
                display = "";
            }
        });

        Button plusButton = findViewById(R.id.plusButton);
        plusButton.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                operation = '+';
                num1 = Double.parseDouble(display);
                display = "";
            }
        });

        Button equalButton = findViewById(R.id.equalButton);
        equalButton.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                num2 = Double.parseDouble(display);
                double result = 0;
                switch (operation) {
                    case '/':
                        if (num2 == 0) {
                            resultTextView.setText("Error");
                        } else {
                            result = num1 / num2;
                            resultTextView.setText(String.valueOf(result));
                        }
                        break;
                    case '*':
                        result = num1 * num2;
                        resultTextView.setText(String.valueOf(result));
                        break;
                    case '-':
                        result = num1 - num2;
                        resultTextView.setText(String.valueOf(result));
                        break;
                    case '+':
                        result = num1 + num2;
                        resultTextView.setText(String.valueOf(result));
                        break;
                }
            }
        });

        Button dotButton = findViewById(R.id.dotButton);
        dotButton.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                if (!display.contains(".")) {
                    display += ".";
                    resultTextView.setText(display);
                }
            }
        });

        Button zeroButton = findViewById(R.id.zeroButton);
        zeroButton.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                display += "0";
                resultTextView.setText(display);
            }
        });

        Button oneButton = findViewById(R.id.oneButton);
        oneButton.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                display += "1";
                resultTextView.setText(display);
            }
        });

        Button twoButton = findViewById(R.id.twoButton);
        twoButton.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                display += "2";
                resultTextView.setText(display);
            }
        });

        Button threeButton = findViewById(R.id.threeButton);
        threeButton.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                display += "3";
                resultTextView.setText(display);
            }
        });

        Button fourButton = findViewById(R.id.fourButton);
        fourButton.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                display += "4";
                resultTextView.setText(display);
            }
        });

        Button fiveButton = findViewById(R.id.fiveButton);
        fiveButton.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                display += "5";
                resultTextView.setText(display);
            }
        });

        Button sixButton = findViewById(R.id.sixButton);
        sixButton.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                display += "6";
                resultTextView.setText(display);
            }
        });

        Button sevenButton = findViewById(R.id.sevenButton);
        sevenButton.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                display += "7";
                resultTextView.setText(display);
            }
        });

        Button eightButton = findViewById(R.id.eightButton);
        eightButton.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                display += "8";
                resultTextView.setText(display);
            }
        });

        Button nineButton = findViewById(R.id.nineButton);
        nineButton.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                display += "9";
                resultTextView.setText(display);
            }
        });
    }
}

4. 运行应用程序，您现在可以在模拟器或设备上测试它了。