生成一个Android的计算器的代码

以下是一个简单的Android计算器应用程序的代码示例，使用Java语言和Android Studio进行开发：

1. activity_main.xml（应用程序的主布局文件）

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical"
    android:padding="16dp">

    <TextView
        android:id="@+id/tv_result"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:background="@android:color/white"
        android:gravity="right"
        android:padding="8dp"
        android:text="0"
        android:textSize="24sp" />

    <GridLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:columnCount="4"
        android:rowCount="5">

        <Button
            android:id="@+id/btn_1"
            android:layout_width="0dp"
            android:layout_height="wrap_content"
            android:layout_columnWeight="1"
            android:layout_rowWeight="1"
            android:text="1"
            android:textSize="24sp" />

        <Button
            android:id="@+id/btn_2"
            android:layout_width="0dp"
            android:layout_height="wrap_content"
            android:layout_columnWeight="1"
            android:layout_rowWeight="1"
            android:text="2"
            android:textSize="24sp" />

        <Button
            android:id="@+id/btn_3"
            android:layout_width="0dp"
            android:layout_height="wrap_content"
            android:layout_columnWeight="1"
            android:layout_rowWeight="1"
            android:text="3"
            android:textSize="24sp" />

        <Button
            android:id="@+id/btn_add"
            android:layout_width="0dp"
            android:layout_height="wrap_content"
            android:layout_columnWeight="1"
            android:layout_rowWeight="1"
            android:text="+"
            android:textSize="24sp" />

        <Button
            android:id="@+id/btn_4"
            android:layout_width="0dp"
            android:layout_height="wrap_content"
            android:layout_columnWeight="1"
            android:layout_rowWeight="1"
            android:text="4"
            android:textSize="24sp" />

        <Button
            android:id="@+id/btn_5"
            android:layout_width="0dp"
            android:layout_height="wrap_content"
            android:layout_columnWeight="1"
            android:layout_rowWeight="1"
            android:text="5"
            android:textSize="24sp" />

        <Button
            android:id="@+id/btn_6"
            android:layout_width="0dp"
            android:layout_height="wrap_content"
            android:layout_columnWeight="1"
            android:layout_rowWeight="1"
            android:text="6"
            android:textSize="24sp" />

        <Button
            android:id="@+id/btn_subtract"
            android:layout_width="0dp"
            android:layout_height="wrap_content"
            android:layout_columnWeight="1"
            android:layout_rowWeight="1"
            android:text="-"
            android:textSize="24sp" />

        <Button
            android:id="@+id/btn_7"
            android:layout_width="0dp"
            android:layout_height="wrap_content"
            android:layout_columnWeight="1"
            android:layout_rowWeight="1"
            android:text="7"
            android:textSize="24sp" />

        <Button
            android:id="@+id/btn_8"
            android:layout_width="0dp"
            android:layout_height="wrap_content"
            android:layout_columnWeight="1"
            android:layout_rowWeight="1"
            android:text="8"
            android:textSize="24sp" />

        <Button
            android:id="@+id/btn_9"
            android:layout_width="0dp"
            android:layout_height="wrap_content"
            android:layout_columnWeight="1"
            android:layout_rowWeight="1"
            android:text="9"
            android:textSize="24sp" />

        <Button
            android:id="@+id/btn_multiply"
            android:layout_width="0dp"
            android:layout_height="wrap_content"
            android:layout_columnWeight="1"
            android:layout_rowWeight="1"
            android:text="*"
            android:textSize="24sp" />

        <Button
            android:id="@+id/btn_clear"
            android:layout_width="0dp"
            android:layout_height="wrap_content"
            android:layout_columnWeight="1"
            android:layout_rowWeight="1"
            android:layout_gravity="bottom"
            android:text="C"
            android:textSize="24sp" />

        <Button
            android:id="@+id/btn_0"
            android:layout_width="0dp"
            android:layout_height="wrap_content"
            android:layout_columnWeight="1"
            android:layout_rowWeight="1"
            android:text="0"
            android:textSize="24sp" />

        <Button
            android:id="@+id/btn_equals"
            android:layout_width="0dp"
            android:layout_height="wrap_content"
            android:layout_columnWeight="1"
            android:layout_rowWeight="1"
            android:text="="
            android:textSize="24sp" />

        <Button
            android:id="@+id/btn_divide"
            android:layout_width="0dp"
            android:layout_height="wrap_content"
            android:layout_columnWeight="1"
            android:layout_rowWeight="1"
            android:text="/"
            android:textSize="24sp" />

    </GridLayout>

</LinearLayout>

2. MainActivity.java（应用程序的主要代码逻辑）

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

import androidx.appcompat.app.AppCompatActivity;

public class MainActivity extends AppCompatActivity {

    private TextView tvResult;
    private String currentNumber;
    private String operator;
    private double result;

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

        tvResult = findViewById(R.id.tv_result);
        currentNumber = "0";
        operator = "";
        result = 0;

        Button btn1 = findViewById(R.id.btn_1);
        btn1.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                handleNumberInput("1");
            }
        });

        Button btn2 = findViewById(R.id.btn_2);
        btn2.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                handleNumberInput("2");
            }
        });

        Button btn3 = findViewById(R.id.btn_3);
        btn3.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                handleNumberInput("3");
            }
        });

        Button btn4 = findViewById(R.id.btn_4);
        btn4.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                handleNumberInput("4");
            }
        });

        Button btn5 = findViewById(R.id.btn_5);
        btn5.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                handleNumberInput("5");
            }
        });

        Button btn6 = findViewById(R.id.btn_6);
        btn6.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                handleNumberInput("6");
            }
        });

        Button btn7 = findViewById(R.id.btn_7);
        btn7.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                handleNumberInput("7");
            }
        });

        Button btn8 = findViewById(R.id.btn_8);
        btn8.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                handleNumberInput("8");
            }
        });

        Button btn9 = findViewById(R.id.btn_9);
        btn9.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                handleNumberInput("9");
            }
        });

        Button btn0 = findViewById(R.id.btn_0);
        btn0.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                handleNumberInput("0");
            }
        });

        Button btnAdd = findViewById(R.id.btn_add);
        btnAdd.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                handleOperatorInput("+");
            }
        });

        Button btnSubtract = findViewById(R.id.btn_subtract);
        btnSubtract.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                handleOperatorInput("-");
            }
        });

        Button btnMultiply = findViewById(R.id.btn_multiply);
        btnMultiply.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                handleOperatorInput("*");
            }
        });

        Button btnDivide = findViewById(R.id.btn_divide);
        btnDivide.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                handleOperatorInput("/");
            }
        });

        Button btnClear = findViewById(R.id.btn_clear);
        btnClear.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                currentNumber = "0";
                operator = "";
                result = 0;
                tvResult.setText("0");
            }
        });

        Button btnEquals = findViewById(R.id.btn_equals);
        btnEquals.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                calculateResult();
            }
        });
    }

    private void handleNumberInput(String number) {
        if (currentNumber.equals("0")) {
            currentNumber = number;
        } else {
            currentNumber += number;
        }
        tvResult.setText(currentNumber);
    }

    private void handleOperatorInput(String op) {
        if (operator.isEmpty()) {
            result = Double.parseDouble(currentNumber);
        } else {
            calculateResult();
        }
        operator = op;
        currentNumber = "0";
    }

    private void calculateResult() {
        if (operator.isEmpty()) {
            return;
        }
        double currentNumberValue = Double.parseDouble(currentNumber);
        switch (operator) {
            case "+":
                result += currentNumberValue;
                break;
            case "-":
                result -= currentNumberValue;
                break;
            case "*":
                result *= currentNumberValue;
                break;
            case "/":
                if (currentNumberValue == 0) {
                    tvResult.setText("Error");
                    return;
                }
                result /= currentNumberValue;
                break;
        }
        currentNumber = String.valueOf(result);
        operator = "";
        tvResult.setText(currentNumber);
    }
}

这是一个简单的四则运算计算器应用程序，用户可以在应用程序中输入数字和运算符，并按下“=”按钮计算结果。