安卓计算器包含加减乘除以及按钮0到9且能实现连乘连加的MainActivity代码

以下是一个简单的实现加减乘除以及按钮0到9且能实现连乘连加的安卓计算器MainActivity代码：

public class MainActivity extends AppCompatActivity implements View.OnClickListener {

    private TextView tvResult;
    private Button btnAdd, btnSubtract, btnMultiply, btnDivide, btnClear, btnEquals, btnDecimal;
    private Button btn0, btn1, btn2, btn3, btn4, btn5, btn6, btn7, btn8, btn9;

    private String currentNumber = "";
    private String currentOperator = "";
    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);
        btnAdd = findViewById(R.id.btn_add);
        btnSubtract = findViewById(R.id.btn_subtract);
        btnMultiply = findViewById(R.id.btn_multiply);
        btnDivide = findViewById(R.id.btn_divide);
        btnClear = findViewById(R.id.btn_clear);
        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);

        btnAdd.setOnClickListener(this);
        btnSubtract.setOnClickListener(this);
        btnMultiply.setOnClickListener(this);
        btnDivide.setOnClickListener(this);
        btnClear.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 v) {
        switch (v.getId()) {
            case R.id.btn_0:
                currentNumber += "0";
                tvResult.setText(currentNumber);
                break;
            case R.id.btn_1:
                currentNumber += "1";
                tvResult.setText(currentNumber);
                break;
            case R.id.btn_2:
                currentNumber += "2";
                tvResult.setText(currentNumber);
                break;
            case R.id.btn_3:
                currentNumber += "3";
                tvResult.setText(currentNumber);
                break;
            case R.id.btn_4:
                currentNumber += "4";
                tvResult.setText(currentNumber);
                break;
            case R.id.btn_5:
                currentNumber += "5";
                tvResult.setText(currentNumber);
                break;
            case R.id.btn_6:
                currentNumber += "6";
                tvResult.setText(currentNumber);
                break;
            case R.id.btn_7:
                currentNumber += "7";
                tvResult.setText(currentNumber);
                break;
            case R.id.btn_8:
                currentNumber += "8";
                tvResult.setText(currentNumber);
                break;
            case R.id.btn_9:
                currentNumber += "9";
                tvResult.setText(currentNumber);
                break;
            case R.id.btn_decimal:
                if (!currentNumber.contains(".")) {
                    currentNumber += ".";
                    tvResult.setText(currentNumber);
                }
                break;
            case R.id.btn_clear:
                currentNumber = "";
                currentOperator = "";
                result = 0.0;
                tvResult.setText("");
                break;
            case R.id.btn_add:
                performOperation("+");
                break;
            case R.id.btn_subtract:
                performOperation("-");
                break;
            case R.id.btn_multiply:
                performOperation("*");
                break;
            case R.id.btn_divide:
                performOperation("/");
                break;
            case R.id.btn_equals:
                performEquals();
                break;
        }
    }

    private void performOperation(String operator) {
        if (currentOperator.equals("")) {
            result = Double.parseDouble(currentNumber);
            currentNumber = "";
            currentOperator = operator;
        } else {
            if (!currentNumber.equals("")) {
                double current = Double.parseDouble(currentNumber);
                switch (currentOperator) {
                    case "+":
                        result += current;
                        break;
                    case "-":
                        result -= current;
                        break;
                    case "*":
                        result *= current;
                        break;
                    case "/":
                        result /= current;
                        break;
                }
                currentNumber = "";
            }
            currentOperator = operator;
        }
        tvResult.setText(String.valueOf(result));
    }

    private void performEquals() {
        if (!currentNumber.equals("") && !currentOperator.equals("")) {
            double current = Double.parseDouble(currentNumber);
            switch (currentOperator) {
                case "+":
                    result += current;
                    break;
                case "-":
                    result -= current;
                    break;
                case "*":
                    result *= current;
                    break;
                case "/":
                    result /= current;
                    break;
            }
            currentNumber = "";
            currentOperator = "";
            tvResult.setText(String.valueOf(result));
        }
    }
}

该代码使用了一个 `currentNumber` 变量来存储当前输入的数字，一个 `currentOperator` 变量来存储当前操作符，以及一个 `result` 变量来存储计算结果。当用户点击数字或操作符按钮时，通过调用相应的方法进行处理。其中，`performOperation` 方法用于处理加减乘除运算，`performEquals` 方法用于处理等于运算。最后，将结果显示在 `tvResult` TextView 中。