java - 安卓工作室 : error: incompatible types: double cannot be converted to String

Question

我是 android studio 的新手，正在尝试制作一个计算器应用程序。我的几乎所有按钮都可以使用(0-9)，但我只需要对加法、减法、乘法和除法按钮进行编程。现在我遇到了一个问题:

error: incompatible types: double cannot be converted to String.

我真的不知道如何改变它让它工作。这是我的代码的一部分:

//Button A (Addition) Event Handler
    buttonA.setOnClickListener(
            //Button A Interface
            new Button.OnClickListener(){
                //Button A Callback Method
                public void onClick(View v){
                    TextView output = (TextView)findViewById(R.id.editText);
                    tempDouble = Double.parseDouble(output.getText().toString());
                    output.setText("");
                    sign = "+";
                }
            }
    );

    //Button S (Subtract) Event Handler
    buttonS.setOnClickListener(
            //Button S Interface
            new Button.OnClickListener(){
                //Button S Callback Method
                public void onClick(View v){
                    TextView output = (TextView)findViewById(R.id.editText);
                    tempDouble = Double.parseDouble(output.getText().toString());
                    output.setText("");
                    sign = "-";
                }
            }
    );

    //Button D (Divide) Event Handler
    buttonD.setOnClickListener(
            //Button D Interface
            new Button.OnClickListener(){
                //Button D Callback Method
                public void onClick(View v){
                    TextView output = (TextView)findViewById(R.id.editText);
                    tempDouble = Double.parseDouble(output.getText().toString());
                    output.setText("");
                    sign = "/";
                }
            }
    );

    //Button M (Multiply) Event Handler
    buttonM.setOnClickListener(
            //Button M Interface
            new Button.OnClickListener(){
                //Button M Callback Method
                public void onClick(View v){
                    TextView output = (TextView)findViewById(R.id.editText);
                    tempDouble = Double.parseDouble(output.getText().toString());
                    output.setText("");
                    sign = "*";
                }
            }
    );

    //Button Equals
    buttonE.setOnClickListener(
            new Button.OnClickListener(){
                public void onClick(View v){
                    TextView output = (TextView)findViewById(R.id.editText);
                    tempDouble2 = Double.parseDouble(output.getText().toString());

                    if (sign .equals("+")){
                        output.setText(Double.toString(tempDouble + tempDouble2));
                    }
                    else if (sign .equals("-")){
                        output.setText(Double.toString(tempDouble - tempDouble2));
                    }
                    else if (sign .equals("X"))){
                        output.setText(Double.toString(tempDouble * tempDouble2));
                    }
                    else if (sign .equals("/")){
                        if (tempDouble2 == 0){
                            //Cannot devide by zero
                            output.setText("X");
                        }
                        else {
                            output.setText(Double.toString(tempDouble / tempDouble2));
                        }
                    }

                    //Reset the Sign variable
                    sign = "";
                }
            }
    );
}

我也得到了错误:

error: bad operand types for binary operator '-'

error: bad operand types for binary operator '*'

error: bad operand types for binary operator '/'

有经验的人可以帮帮我吗？

Answer 1

您不能在两个 Double 对象之间使用“+”运算符。

如果你想将 Double 转换为 String，你应该使用

String.valueOf(tempDouble);

如果你想添加两个 Double 对象，你应该使用

tempDouble.doubleValue() + tempDouble2;