android studio实现计算器的加减乘除、乘方、开方

首先，在 Android Studio 中创建一个新项目，然后在布局文件中添加一个 TextView 和多个 Button，以实现计算器的界面。

接下来，在 MainActivity.java 中编写代码来实现计算器的功能。以下是一个简单的实现示例：

import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.TextView;
import androidx.appcompat.app.AppCompatActivity;
import java.text.DecimalFormat;

public class MainActivity extends AppCompatActivity implements View.OnClickListener {

    private TextView mDisplayText;
    private Button mButton0, mButton1, mButton2, mButton3, mButton4, mButton5, mButton6, mButton7, mButton8, mButton9;
    private Button mButtonPlus, mButtonMinus, mButtonMultiply, mButtonDivide, mButtonPower, mButtonSqrt, mButtonEqual, mButtonClear;
    private String mNumber1 = "", mNumber2 = "", mOperator = "";
    private DecimalFormat mDecimalFormat;

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

        mDisplayText = findViewById(R.id.display_text);
        mButton0 = findViewById(R.id.button_0);
        mButton1 = findViewById(R.id.button_1);
        mButton2 = findViewById(R.id.button_2);
        mButton3 = findViewById(R.id.button_3);
        mButton4 = findViewById(R.id.button_4);
        mButton5 = findViewById(R.id.button_5);
        mButton6 = findViewById(R.id.button_6);
        mButton7 = findViewById(R.id.button_7);
        mButton8 = findViewById(R.id.button_8);
        mButton9 = findViewById(R.id.button_9);
        mButtonPlus = findViewById(R.id.button_plus);
        mButtonMinus = findViewById(R.id.button_minus);
        mButtonMultiply = findViewById(R.id.button_multiply);
        mButtonDivide = findViewById(R.id.button_divide);
        mButtonPower = findViewById(R.id.button_power);
        mButtonSqrt = findViewById(R.id.button_sqrt);
        mButtonEqual = findViewById(R.id.button_equal);
        mButtonClear = findViewById(R.id.button_clear);

        mDecimalFormat = new DecimalFormat("#.##########");

        mButton0.setOnClickListener(this);
        mButton1.setOnClickListener(this);
        mButton2.setOnClickListener(this);
        mButton3.setOnClickListener(this);
        mButton4.setOnClickListener(this);
        mButton5.setOnClickListener(this);
        mButton6.setOnClickListener(this);
        mButton7.setOnClickListener(this);
        mButton8.setOnClickListener(this);
        mButton9.setOnClickListener(this);
        mButtonPlus.setOnClickListener(this);
        mButtonMinus.setOnClickListener(this);
        mButtonMultiply.setOnClickListener(this);
        mButtonDivide.setOnClickListener(this);
        mButtonPower.setOnClickListener(this);
        mButtonSqrt.setOnClickListener(this);
        mButtonEqual.setOnClickListener(this);
        mButtonClear.setOnClickListener(this);
    }

    @Override
    public void onClick(View view) {
        switch (view.getId()) {
            case R.id.button_0:
                onNumberClicked("0");
                break;
            case R.id.button_1:
                onNumberClicked("1");
                break;
            case R.id.button_2:
                onNumberClicked("2");
                break;
            case R.id.button_3:
                onNumberClicked("3");
                break;
            case R.id.button_4:
                onNumberClicked("4");
                break;
            case R.id.button_5:
                onNumberClicked("5");
                break;
            case R.id.button_6:
                onNumberClicked("6");
                break;
            case R.id.button_7:
                onNumberClicked("7");
                break;
            case R.id.button_8:
                onNumberClicked("8");
                break;
            case R.id.button_9:
                onNumberClicked("9");
                break;
            case R.id.button_plus:
                onOperatorClicked("+");
                break;
            case R.id.button_minus:
                onOperatorClicked("-");
                break;
            case R.id.button_multiply:
                onOperatorClicked("*");
                break;
            case R.id.button_divide:
                onOperatorClicked("/");
                break;
            case R.id.button_power:
                onOperatorClicked("^");
                break;
            case R.id.button_sqrt:
                onOperatorClicked("sqrt");
                break;
            case R.id.button_equal:
                onEqualClicked();
                break;
            case R.id.button_clear:
                onClearClicked();
                break;
        }
    }

    private void onNumberClicked(String number) {
        if (mOperator.isEmpty()) {
            mNumber1 += number;
            mDisplayText.setText(mNumber1);
        } else {
            mNumber2 += number;
            mDisplayText.setText(mNumber2);
        }
    }

    private void onOperatorClicked(String operator) {
        if (!mNumber1.isEmpty() && mNumber2.isEmpty()) {
            mOperator = operator;
            mDisplayText.setText(mNumber1 + " " + operator + " ");
        }
    }

    private void onEqualClicked() {
        double result = 0.0;
        if (!mNumber1.isEmpty() && !mNumber2.isEmpty()) {
            double num1 = Double.parseDouble(mNumber1);
            double num2 = Double.parseDouble(mNumber2);
            switch (mOperator) {
                case "+":
                    result = num1 + num2;
                    break;
                case "-":
                    result = num1 - num2;
                    break;
                case "*":
                    result = num1 * num2;
                    break;
                case "/":
                    result = num1 / num2;
                    break;
                case "^":
                    result = Math.pow(num1, num2);
                    break;
            }
            mDisplayText.setText(mDecimalFormat.format(result));
            mNumber1 = mDecimalFormat.format(result);
            mNumber2 = "";
            mOperator = "";
        } else if (!mNumber1.isEmpty() && mNumber2.isEmpty() && mOperator.equals("sqrt")) {
            double num1 = Double.parseDouble(mNumber1);
            result = Math.sqrt(num1);
            mDisplayText.setText(mDecimalFormat.format(result));
            mNumber1 = mDecimalFormat.format(result);
            mNumber2 = "";
            mOperator = "";
        }
    }

    private void onClearClicked() {
        mNumber1 = "";
        mNumber2 = "";
        mOperator = "";
        mDisplayText.setText("");
    }
}

在这个示例代码中，我们实现了加、减、乘、除、乘方、开方等基本算术运算，并且使用 DecimalFormat 对结果进行格式化。当用户点击数字按钮时，我们将数字添加到当前操作数中；当用户点击操作符按钮时，我们将当前操作数视为第一个操作数，并将操作符保存；当用户点击等号按钮时，我们计算结果并在 TextView 中显示；当用户点击清除按钮时，我们将所有操作数和操作符都重置为初始状态。

最后，运行应用程序并测试计算器的功能。