用java编写安卓版一个计算器

好的，以下是一个简单的安卓版计算器的Java代码示例：

import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import androidx.appcompat.app.AppCompatActivity;

public class MainActivity extends AppCompatActivity implements View.OnClickListener {

    private Button btn0, btn1, btn2, btn3, btn4, btn5, btn6, btn7, btn8, btn9;
    private Button btnAdd, btnSub, btnMul, btnDiv, btnClear, btnEqual;
    private EditText etInput;
    private boolean clearFlag; //判断是否清空
    private String operator = ""; //运算符

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

        //获取控件对象
        etInput = findViewById(R.id.et_input);
        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 = findViewById(R.id.btn_add);
        btnSub = findViewById(R.id.btn_sub);
        btnMul = findViewById(R.id.btn_mul);
        btnDiv = findViewById(R.id.btn_div);
        btnClear = findViewById(R.id.btn_clear);
        btnEqual = findViewById(R.id.btn_equal);

        //设置按钮的点击事件监听器
        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);
        btnAdd.setOnClickListener(this);
        btnSub.setOnClickListener(this);
        btnMul.setOnClickListener(this);
        btnDiv.setOnClickListener(this);
        btnClear.setOnClickListener(this);
        btnEqual.setOnClickListener(this);
    }

    @Override
    public void onClick(View v) {
        String str = etInput.getText().toString();
        switch (v.getId()) {
            case R.id.btn_0:
            case R.id.btn_1:
            case R.id.btn_2:
            case R.id.btn_3:
            case R.id.btn_4:
            case R.id.btn_5:
            case R.id.btn_6:
            case R.id.btn_7:
            case R.id.btn_8:
            case R.id.btn_9:
                if (clearFlag) {
                    clearFlag = false;
                    str = "";
                    etInput.setText("");
                }
                etInput.setText(str + ((Button) v).getText());
                break;
            case R.id.btn_add:
            case R.id.btn_sub:
            case R.id.btn_mul:
            case R.id.btn_div:
                if (clearFlag) {
                    clearFlag = false;
                    str = "";
                    etInput.setText("");
                }
                operator = ((Button) v).getText().toString();
                etInput.setText(str + operator);
                break;
            case R.id.btn_clear:
                clearFlag = false;
                str = "";
                etInput.setText("");
                break;
            case R.id.btn_equal:
                if (clearFlag) {
                    clearFlag = false;
                    return;
                }
                clearFlag = true;
                if (operator.equals("")) {
                    return;
                }
                String[] arr = str.split("\\" + operator);
                double result = 0;
                switch (operator) {
                    case "+":
                        result = Double.parseDouble(arr[0]) + Double.parseDouble(arr[1]);
                        break;
                    case "-":
                        result = Double.parseDouble(arr[0]) - Double.parseDouble(arr[1]);
                        break;
                    case "*":
                        result = Double.parseDouble(arr[0]) * Double.parseDouble(arr[1]);
                        break;
                    case "/":
                        if (Double.parseDouble(arr[1]) == 0) {
                            etInput.setText("除数不能为0");
                            return;
                        }
                        result = Double.parseDouble(arr[0]) / Double.parseDouble(arr[1]);
                        break;
                }
                etInput.setText(result + "");
                break;
        }
    }
}

此代码中实现了基本的加减乘除运算、清空和等于功能。同时，为了方便用户操作，还可以在布局文件中添加一些其他的控件，例如小数点、正负号等。