android实现一个简易多功能计算器代码和布局文件

以下是一个简单的 Android 计算器的布局文件和代码：

layout/activity_main.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="vertical"
    android:layout_width="match_parent"
    android:layout_height="match_parent">
    
    <TextView
        android:id="@+id/tv_result"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:textSize="30sp"
        android:padding="16dp"
        android:gravity="right"
        android:textColor="@android:color/black" />
        
    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:orientation="horizontal">
        
        <Button
            android:id="@+id/btn_clear"
            android:text="C"
            android:textSize="24sp"
            android:layout_weight="1"
            android:layout_width="0dp"
            android:layout_height="wrap_content" />
            
        <Button
            android:id="@+id/btn_divide"
            android:text="/"
            android:textSize="24sp"
            android:layout_weight="1"
            android:layout_width="0dp"
            android:layout_height="wrap_content" />
            
        <Button
            android:id="@+id/btn_multiply"
            android:text="*"
            android:textSize="24sp"
            android:layout_weight="1"
            android:layout_width="0dp"
            android:layout_height="wrap_content" />
            
        <Button
            android:id="@+id/btn_minus"
            android:text="-"
            android:textSize="24sp"
            android:layout_weight="1"
            android:layout_width="0dp"
            android:layout_height="wrap_content" />
    </LinearLayout>
    
    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:orientation="horizontal">
        
        <Button
            android:id="@+id/btn_7"
            android:text="7"
            android:textSize="24sp"
            android:layout_weight="1"
            android:layout_width="0dp"
            android:layout_height="wrap_content" />
            
        <Button
            android:id="@+id/btn_8"
            android:text="8"
            android:textSize="24sp"
            android:layout_weight="1"
            android:layout_width="0dp"
            android:layout_height="wrap_content" />
            
        <Button
            android:id="@+id/btn_9"
            android:text="9"
            android:textSize="24sp"
            android:layout_weight="1"
            android:layout_width="0dp"
            android:layout_height="wrap_content" />
            
        <Button
            android:id="@+id/btn_plus"
            android:text="+"
            android:textSize="24sp"
            android:layout_weight="1"
            android:layout_width="0dp"
            android:layout_height="wrap_content" />
    </LinearLayout>
    
    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:orientation="horizontal">
        
        <Button
            android:id="@+id/btn_4"
            android:text="4"
            android:textSize="24sp"
            android:layout_weight="1"
            android:layout_width="0dp"
            android:layout_height="wrap_content" />
            
        <Button
            android:id="@+id/btn_5"
            android:text="5"
            android:textSize="24sp"
            android:layout_weight="1"
            android:layout_width="0dp"
            android:layout_height="wrap_content" />
            
        <Button
            android:id="@+id/btn_6"
            android:text="6"
            android:textSize="24sp"
            android:layout_weight="1"
            android:layout_width="0dp"
            android:layout_height="wrap_content" />
            
        <Button
            android:id="@+id/btn_equals"
            android:text="="
            android:textSize="24sp"
            android:layout_weight="1"
            android:layout_width="0dp"
            android:layout_height="wrap_content" />
    </LinearLayout>
    
    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:orientation="horizontal">
        
        <Button
            android:id="@+id/btn_1"
            android:text="1"
            android:textSize="24sp"
            android:layout_weight="1"
            android:layout_width="0dp"
            android:layout_height="wrap_content" />
            
        <Button
            android:id="@+id/btn_2"
            android:text="2"
            android:textSize="24sp"
            android:layout_weight="1"
            android:layout_width="0dp"
            android:layout_height="wrap_content" />
            
        <Button
            android:id="@+id/btn_3"
            android:text="3"
            android:textSize="24sp"
            android:layout_weight="1"
            android:layout_width="0dp"
            android:layout_height="wrap_content" />
            
        <Button
            android:id="@+id/btn_decimal"
            android:text="."
            android:textSize="24sp"
            android:layout_weight="1"
            android:layout_width="0dp"
            android:layout_height="wrap_content" />
    </LinearLayout>
    
    <Button
        android:id="@+id/btn_0"
        android:text="0"
        android:textSize="24sp"
        android:layout_width="match_parent"
        android:layout_height="wrap_content" />
        
</LinearLayout>

Java/MainActivity.java

public class MainActivity extends AppCompatActivity implements View.OnClickListener {
    private TextView tvResult;
    private Button btnClear, btnDivide, btnMultiply, btnMinus, btnPlus, btnEquals, btnDecimal;
    private Button btn0, btn1, btn2, btn3, btn4, btn5, btn6, btn7, btn8, btn9;
    
    private String currentNumber = "";
    private String operation = "";
    private double result = 0.0;
    
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        
        tvResult = findViewById(R.id.tv_result);
        btnClear = findViewById(R.id.btn_clear);
        btnDivide = findViewById(R.id.btn_divide);
        btnMultiply = findViewById(R.id.btn_multiply);
        btnMinus = findViewById(R.id.btn_minus);
        btnPlus = findViewById(R.id.btn_plus);
        btnEquals = findViewById(R.id.btn_equals);
        btnDecimal = findViewById(R.id.btn_decimal);
        
        btn0 = findViewById(R.id.btn_0);
        btn1 = findViewById(R.id.btn_1);
        btn2 = findViewById(R.id.btn_2);
        btn3 = findViewById(R.id.btn_3);
        btn4 = findViewById(R.id.btn_4);
        btn5 = findViewById(R.id.btn_5);
        btn6 = findViewById(R.id.btn_6);
        btn7 = findViewById(R.id.btn_7);
        btn8 = findViewById(R.id.btn_8);
        btn9 = findViewById(R.id.btn_9);
        
        btnClear.setOnClickListener(this);
        btnDivide.setOnClickListener(this);
        btnMultiply.setOnClickListener(this);
        btnMinus.setOnClickListener(this);
        btnPlus.setOnClickListener(this);
        btnEquals.setOnClickListener(this);
        btnDecimal.setOnClickListener(this);
        
        btn0.setOnClickListener(this);
        btn1.setOnClickListener(this);
        btn2.setOnClickListener(this);
        btn3.setOnClickListener(this);
        btn4.setOnClickListener(this);
        btn5.setOnClickListener(this);
        btn6.setOnClickListener(this);
        btn7.setOnClickListener(this);
        btn8.setOnClickListener(this);
        btn9.setOnClickListener(this);
    }
    
    @Override
    public void onClick(View view) {
        switch (view.getId()) {
            case R.id.btn_clear:
                currentNumber = "";
                operation = "";
                result = 0.0;
                tvResult.setText("");
                break;
                
            case R.id.btn_divide:
                performOperation("/");
                break;
                
            case R.id.btn_multiply:
                performOperation("*");
                break;
                
            case R.id.btn_minus:
                performOperation("-");
                break;
                
            case R.id.btn_plus:
                performOperation("+");
                break;
                
            case R.id.btn_equals:
                calculateResult();
                break;
                
            case R.id.btn_decimal:
                if (!currentNumber.contains(".")) {
                    currentNumber += ".";
                }
                tvResult.setText(currentNumber);
                break;
                
            case R.id.btn_0:
                appendNumber("0");
                break;
                
            case R.id.btn_1:
                appendNumber("1");
                break;
                
            case R.id.btn_2:
                appendNumber("2");
                break;
                
            case R.id.btn_3:
                appendNumber("3");
                break;
                
            case R.id.btn_4:
                appendNumber("4");
                break;
                
            case R.id.btn_5:
                appendNumber("5");
                break;
                
            case R.id.btn_6:
                appendNumber("6");
                break;
                
            case R.id.btn_7:
                appendNumber("7");
                break;
                
            case R.id.btn_8:
                appendNumber("8");
                break;
                
            case R.id.btn_9:
                appendNumber("9");
                break;
        }
    }
    
    private void appendNumber(String number) {
        currentNumber += number;
        tvResult.setText(currentNumber);
    }
    
    private void performOperation(String op) {
        if (operation.isEmpty()) {
            result = Double.parseDouble(currentNumber);
            operation = op;
            currentNumber = "";
        } else {
            calculateResult();
            operation = op;
        }
    }
    
    private void calculateResult() {
        if (operation.isEmpty()) {
            return;
        }
        
        double secondNumber = Double.parseDouble(currentNumber);
        
        switch (operation) {
            case "+":
                result += secondNumber;
                break;
                
            case "-":
                result -= secondNumber;
                break;
                
            case "*":
                result *= secondNumber;
                break;
                
            case "/":
                result /= secondNumber;
                break;
        }
        
        currentNumber = "";
        operation = "";
        tvResult.setText(String.valueOf(result));
    }
}