Android Studio 生成计算器

好的，让我们开始吧！

首先，在 Android Studio 中创建一个新的项目。

然后，在新项目的 `activity_main.xml` 文件中添加一个布局，用于显示计算器的界面。可以使用 LinearLayout、RelativeLayout 或者其他布局方式来实现。这里以 LinearLayout 为例：

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical">

    <!-- 显示计算结果的文本框 -->
    <TextView
        android:id="@+id/resultTextView"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:textSize="24sp"
        android:gravity="right"
        android:text="@string/result_text" />

    <!-- 数字和操作符按钮的布局 -->
    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:orientation="horizontal">

        <!-- 数字按钮 -->
        <LinearLayout
            android:layout_width="0dp"
            android:layout_height="match_parent"
            android:layout_weight="3"
            android:orientation="vertical">

            <LinearLayout
                android:layout_width="match_parent"
                android:layout_height="0dp"
                android:layout_weight="1"
                android:orientation="horizontal">

                <Button
                    android:id="@+id/button0"
                    android:layout_width="0dp"
                    android:layout_height="match_parent"
                    android:layout_weight="1"
                    android:text="0" />

                <Button
                    android:id="@+id/button1"
                    android:layout_width="0dp"
                    android:layout_height="match_parent"
                    android:layout_weight="1"
                    android:text="1" />

                <Button
                    android:id="@+id/button2"
                    android:layout_width="0dp"
                    android:layout_height="match_parent"
                    android:layout_weight="1"
                    android:text="2" />
            </LinearLayout>

            <LinearLayout
                android:layout_width="match_parent"
                android:layout_height="0dp"
                android:layout_weight="1"
                android:orientation="horizontal">

                <Button
                    android:id="@+id/button3"
                    android:layout_width="0dp"
                    android:layout_height="match_parent"
                    android:layout_weight="1"
                    android:text="3" />

                <Button
                    android:id="@+id/button4"
                    android:layout_width="0dp"
                    android:layout_height="match_parent"
                    android:layout_weight="1"
                    android:text="4" />

                <Button
                    android:id="@+id/button5"
                    android:layout_width="0dp"
                    android:layout_height="match_parent"
                    android:layout_weight="1"
                    android:text="5" />
            </LinearLayout>

            <LinearLayout
                android:layout_width="match_parent"
                android:layout_height="0dp"
                android:layout_weight="1"
                android:orientation="horizontal">

                <Button
                    android:id="@+id/button6"
                    android:layout_width="0dp"
                    android:layout_height="match_parent"
                    android:layout_weight="1"
                    android:text="6" />

                <Button
                    android:id="@+id/button7"
                    android:layout_width="0dp"
                    android:layout_height="match_parent"
                    android:layout_weight="1"
                    android:text="7" />

                <Button
                    android:id="@+id/button8"
                    android:layout_width="0dp"
                    android:layout_height="match_parent"
                    android:layout_weight="1"
                    android:text="8" />
            </LinearLayout>

            <LinearLayout
                android:layout_width="match_parent"
                android:layout_height="0dp"
                android:layout_weight="1"
                android:orientation="horizontal">

                <Button
                    android:id="@+id/button9"
                    android:layout_width="0dp"
                    android:layout_height="match_parent"
                    android:layout_weight="1"
                    android:text="9" />

                <Button
                    android:id="@+id/buttonDot"
                    android:layout_width="0dp"
                    android:layout_height="match_parent"
                    android:layout_weight="1"
                    android:text="." />

                <Button
                    android:id="@+id/buttonClear"
                    android:layout_width="0dp"
                    android:layout_height="match_parent"
                    android:layout_weight="1"
                    android:text="C" />
            </LinearLayout>
        </LinearLayout>

        <!-- 操作符按钮 -->
        <LinearLayout
            android:layout_width="0dp"
            android:layout_height="match_parent"
            android:layout_weight="1"
            android:orientation="vertical">

            <Button
                android:id="@+id/buttonAdd"
                android:layout_width="match_parent"
                android:layout_height="0dp"
                android:layout_weight="1"
                android:text="+" />

            <Button
                android:id="@+id/buttonSubtract"
                android:layout_width="match_parent"
                android:layout_height="0dp"
                android:layout_weight="1"
                android:text="-" />

            <Button
                android:id="@+id/buttonMultiply"
                android:layout_width="match_parent"
                android:layout_height="0dp"
                android:layout_weight="1"
                android:text="×" />

            <Button
                android:id="@+id/buttonDivide"
                android:layout_width="match_parent"
                android:layout_height="0dp"
                android:layout_weight="1"
                android:text="÷" />

            <Button
                android:id="@+id/buttonEquals"
                android:layout_width="match_parent"
                android:layout_height="0dp"
                android:layout_weight="1"
                android:text="=" />
        </LinearLayout>

    </LinearLayout>

</LinearLayout>

接下来，在 `MainActivity.java` 文件中，定义计算器的逻辑和事件处理。在 onCreate() 方法中，找到布局文件中的各个按钮，并设置它们的点击事件。

public class MainActivity extends AppCompatActivity implements View.OnClickListener {

    private TextView resultTextView;

    private Button button0, button1, button2, button3, button4, button5, button6, button7, button8, button9, buttonDot, buttonClear, buttonAdd, buttonSubtract, buttonMultiply, buttonDivide, buttonEquals;

    private String currentNumber = "";
    private String currentOperator = "";
    private String leftOperand = "";
    private String rightOperand = "";

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

        // Find all views by id
        resultTextView = findViewById(R.id.resultTextView);
        button0 = findViewById(R.id.button0);
        button1 = findViewById(R.id.button1);
        button2 = findViewById(R.id.button2);
        button3 = findViewById(R.id.button3);
        button4 = findViewById(R.id.button4);
        button5 = findViewById(R.id.button5);
        button6 = findViewById(R.id.button6);
        button7 = findViewById(R.id.button7);
        button8 = findViewById(R.id.button8);
        button9 = findViewById(R.id.button9);
        buttonDot = findViewById(R.id.buttonDot);
        buttonClear = findViewById(R.id.buttonClear);
        buttonAdd = findViewById(R.id.buttonAdd);
        buttonSubtract = findViewById(R.id.buttonSubtract);
        buttonMultiply = findViewById(R.id.buttonMultiply);
        buttonDivide = findViewById(R.id.buttonDivide);
        buttonEquals = findViewById(R.id.buttonEquals);

        // Set click listeners for all buttons
        button0.setOnClickListener(this);
        button1.setOnClickListener(this);
        button2.setOnClickListener(this);
        button3.setOnClickListener(this);
        button4.setOnClickListener(this);
        button5.setOnClickListener(this);
        button6.setOnClickListener(this);
        button7.setOnClickListener(this);
        button8.setOnClickListener(this);
        button9.setOnClickListener(this);
        buttonDot.setOnClickListener(this);
        buttonClear.setOnClickListener(this);
        buttonAdd.setOnClickListener(this);
        buttonSubtract.setOnClickListener(this);
        buttonMultiply.setOnClickListener(this);
        buttonDivide.setOnClickListener(this);
        buttonEquals.setOnClickListener(this);
    }

    @Override
    public void onClick(View v) {
        switch (v.getId()) {
            case R.id.button0:
                numberClicked("0");
                break;
            case R.id.button1:
                numberClicked("1");
                break;
            case R.id.button2:
                numberClicked("2");
                break;
            case R.id.button3:
                numberClicked("3");
                break;
            case R.id.button4:
                numberClicked("4");
                break;
            case R.id.button5:
                numberClicked("5");
                break;
            case R.id.button6:
                numberClicked("6");
                break;
            case R.id.button7:
                numberClicked("7");
                break;
            case R.id.button8:
                numberClicked("8");
                break;
            case R.id.button9:
                numberClicked("9");
                break;
            case R.id.buttonDot:
                numberClicked(".");
                break;
            case R.id.buttonClear:
                clearClicked();
                break;
            case R.id.buttonAdd:
                operatorClicked("+");
                break;
            case R.id.buttonSubtract:
                operatorClicked("-");
                break;
            case R.id.buttonMultiply:
                operatorClicked("×");
                break;
            case R.id.buttonDivide:
                operatorClicked("÷");
                break;
            case R.id.buttonEquals:
                equalsClicked();
                break;
            default:
                break;
        }
    }

    private void numberClicked(String number) {
        currentNumber += number;
        resultTextView.setText(currentNumber);
    }

    private void clearClicked() {
        currentNumber = "";
        currentOperator = "";
        leftOperand = "";
        rightOperand = "";
        resultTextView.setText(getString(R.string.result_text));
    }

    private void operatorClicked(String operator) {
        if (currentNumber.isEmpty()) {
            return;
        }

        if (currentOperator.isEmpty()) {
            leftOperand = currentNumber;
            currentNumber = "";
            currentOperator = operator;
            resultTextView.setText(leftOperand + " " + currentOperator);
        } else {
            rightOperand = currentNumber;
            currentNumber = "";
            calculateResult();
            leftOperand = resultTextView.getText().toString();
            currentOperator = operator;
            resultTextView.setText(leftOperand + " " + currentOperator);
        }
    }

    private void equalsClicked() {
        if (currentNumber.isEmpty() || currentOperator.isEmpty()) {
            return;
        }

        rightOperand = currentNumber;
        calculateResult();
        currentNumber = "";
        currentOperator = "";
    }

    private void calculateResult() {
        double result = 0.0;
        double leftValue = Double.parseDouble(leftOperand);
        double rightValue = Double.parseDouble(rightOperand);

        switch (currentOperator) {
            case "+":
                result = leftValue + rightValue;
                break;
            case "-":
                result = leftValue - rightValue;
                break;
            case "×":
                result = leftValue * rightValue;
                break;
            case "÷":
                result = leftValue / rightValue;
                break;
            default:
                break;
        }

        resultTextView.setText(String.valueOf(result));
    }
}

这里使用了四个字符串变量，分别用于保存当前输入的数字、当前的操作符、左操作数和右操作数。当用户点击数字按钮时，将数字添加到当前输入的数字中，并更新文本框的内容。当用户点击清除按钮时，将所有变量重置，并将文本框的内容设置为初始值。当用户点击操作符按钮时，根据当前的状态，将左操作数、当前操作符和当前输入的数字保存，并在文本框中显示左操作数和当前操作符。当用户点击等于号时，将右操作数设置为当前输入的数字，并计算出结果，并将结果显示在文本框中。

现在，运行应用程序，你就可以使用这个简单的计算器进行加减乘除运算了！