用android studio制作一个能加减乘除的计算器附上代码

好的，以下是一个简单的能够进行加减乘除运算的计算器的代码。你可以在 Android Studio 中创建一个新的项目，将以下代码复制到 MainActivity.java 文件中，然后运行即可。

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

public class MainActivity extends AppCompatActivity {

    EditText firstNumberEditText, secondNumberEditText;
    TextView resultTextView;

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

        firstNumberEditText = findViewById(R.id.firstNumberEditText);
        secondNumberEditText = findViewById(R.id.secondNumberEditText);
        resultTextView = findViewById(R.id.resultTextView);

        Button addButton = findViewById(R.id.addButton);
        addButton.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                double firstNumber = Double.parseDouble(firstNumberEditText.getText().toString());
                double secondNumber = Double.parseDouble(secondNumberEditText.getText().toString());
                double result = firstNumber + secondNumber;
                resultTextView.setText(Double.toString(result));
            }
        });

        Button subtractButton = findViewById(R.id.subtractButton);
        subtractButton.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                double firstNumber = Double.parseDouble(firstNumberEditText.getText().toString());
                double secondNumber = Double.parseDouble(secondNumberEditText.getText().toString());
                double result = firstNumber - secondNumber;
                resultTextView.setText(Double.toString(result));
            }
        });

        Button multiplyButton = findViewById(R.id.multiplyButton);
        multiplyButton.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                double firstNumber = Double.parseDouble(firstNumberEditText.getText().toString());
                double secondNumber = Double.parseDouble(secondNumberEditText.getText().toString());
                double result = firstNumber * secondNumber;
                resultTextView.setText(Double.toString(result));
            }
        });

        Button divideButton = findViewById(R.id.divideButton);
        divideButton.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                double firstNumber = Double.parseDouble(firstNumberEditText.getText().toString());
                double secondNumber = Double.parseDouble(secondNumberEditText.getText().toString());
                double result = firstNumber / secondNumber;
                resultTextView.setText(Double.toString(result));
            }
        });
    }
}

在布局文件 activity_main.xml 中，可以添加以下代码来创建用户界面：

<LinearLayout
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical"
    android:padding="16dp">

    <EditText
        android:id="@+id/firstNumberEditText"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:hint="Enter first number"/>

    <EditText
        android:id="@+id/secondNumberEditText"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:hint="Enter second number"/>

    <Button
        android:id="@+id/addButton"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="Add"/>

    <Button
        android:id="@+id/subtractButton"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="Subtract"/>

    <Button
        android:id="@+id/multiplyButton"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="Multiply"/>

    <Button
        android:id="@+id/divideButton"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="Divide"/>

    <TextView
        android:id="@+id/resultTextView"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_marginTop="16dp"
        android:text="Result will appear here"
        android:textSize="24sp"/>

</LinearLayout>

运行代码后，你就可以在应用程序中输入两个数字并选择所需的运算类型，然后计算器将返回结果。