android studio做一个计算器，写出相应代码和操作

好的，下面是一个简单的 Android Studio 计算器的代码和操作步骤：

1. 创建一个新的 Android Studio 项目，选择 "Empty Activity" 模板。

2. 打开 activity_main.xml 文件并添加一个 TextView 和一个 GridLayout。TextView 用于显示计算器的输入和输出，而 GridLayout 用于放置计算器的按钮。

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:id="@+id/activity_main"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context="com.example.calculator.MainActivity">

    <TextView
        android:id="@+id/tv_result"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:gravity="right"
        android:textSize="40sp" />

    <GridLayout
        android:layout_below="@id/tv_result"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:rowCount="5"
        android:columnCount="4"
        android:orientation="horizontal">

        <Button
            android:layout_row="0"
            android:layout_column="0"
            android:text="7"
            android:textSize="30sp" />

        <Button
            android:layout_row="0"
            android:layout_column="1"
            android:text="8"
            android:textSize="30sp" />

        <Button
            android:layout_row="0"
            android:layout_column="2"
            android:text="9"
            android:textSize="30sp" />

        <Button
            android:layout_row="0"
            android:layout_column="3"
            android:text="/"
            android:textSize="30sp" />

        <Button
            android:layout_row="1"
            android:layout_column="0"
            android:text="4"
            android:textSize="30sp" />

        <Button
            android:layout_row="1"
            android:layout_column="1"
            android:text="5"
            android:textSize="30sp" />

        <Button
            android:layout_row="1"
            android:layout_column="2"
            android:text="6"
            android:textSize="30sp" />

        <Button
            android:layout_row="1"
            android:layout_column="3"
            android:text="*"
            android:textSize="30sp" />

        <Button
            android:layout_row="2"
            android:layout_column="0"
            android:text="1"
            android:textSize="30sp" />

        <Button
            android:layout_row="2"
            android:layout_column="1"
            android:text="2"
            android:textSize="30sp" />

        <Button
            android:layout_row="2"
            android:layout_column="2"
            android:text="3"
            android:textSize="30sp" />

        <Button
            android:layout_row="2"
            android:layout_column="3"
            android:text="-"
            android:textSize="30sp" />

        <Button
            android:layout_row="3"
            android:layout_column="0"
            android:text="0"
            android:textSize="30sp" />

        <Button
            android:layout_row="3"
            android:layout_column="1"
            android:text="."
            android:textSize="30sp" />

        <Button
            android:layout_row="3"
            android:layout_column="2"
            android:text="C"
            android:textSize="30sp" />

        <Button
            android:layout_row="3"
            android:layout_column="3"
            android:text="+"
            android:textSize="30sp" />

        <Button
            android:layout_row="4"
            android:layout_column="0"
            android:text="("
            android:textSize="30sp" />

        <Button
            android:layout_row="4"
            android:layout_column="1"
            android:text=")"
            android:textSize="30sp" />

        <Button
            android:layout_row="4"
            android:layout_column="2"
            android:text="="
            android:textSize="30sp" />

        <Button
            android:layout_row="4"
            android:layout_column="3"
            android:text="^"
            android:textSize="30sp" />

    </GridLayout>
</RelativeLayout>

3. 打开 MainActivity.java 文件并添加以下代码来为按钮添加点击事件：

public class MainActivity extends AppCompatActivity {

    private TextView tvResult;
    private String currentNumber = "";
    private String leftOperand = "";
    private String rightOperand = "";
    private String operator = "";

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

        tvResult = (TextView) findViewById(R.id.tv_result);

        GridLayout gridLayout = (GridLayout) findViewById(R.id.grid_layout);
        for (int i = 0; i < gridLayout.getChildCount(); i++) {
            View view = gridLayout.getChildAt(i);
            if (view instanceof Button) {
                Button button = (Button) view;
                button.setOnClickListener(new View.OnClickListener() {
                    @Override
                    public void onClick(View view) {
                        Button button = (Button) view;
                        String buttonText = button.getText().toString();
                        switch (buttonText) {
                            case "C":
                                clear();
                                break;
                            case "+":
                            case "-":
                            case "*":
                            case "/":
                            case "^":
                                operator = buttonText;
                                leftOperand = currentNumber;
                                currentNumber = "";
                                break;
                            case "=":
                                rightOperand = currentNumber;
                                currentNumber = calculate();
                                leftOperand = "";
                                rightOperand = "";
                                operator = "";
                                break;
                            default:
                                currentNumber += buttonText;
                                break;
                        }
                        tvResult.setText(currentNumber);
                    }
                });
            }
        }
    }

    private String calculate() {
        double result = 0.0;
        double left = Double.parseDouble(leftOperand);
        double right = Double.parseDouble(rightOperand);
        switch (operator) {
            case "+":
                result = left + right;
                break;
            case "-":
                result = left - right;
                break;
            case "*":
                result = left * right;
                break;
            case "/":
                result = left / right;
                break;
            case "^":
                result = Math.pow(left, right);
                break;
        }
        return Double.toString(result);
    }

    private void clear() {
        currentNumber = "";
        leftOperand = "";
        rightOperand = "";
        operator = "";
        tvResult.setText("");
    }
}

4. 运行项目并在模拟器或实际设备上测试计算器。

这是一个简单的计算器，您可以根据需要进行更改和扩展。