Question

我的程序中有这个问题：当我这样做时：

double a = Double.parseDouble(zero);
double b = Double.parseDouble(data);
double c = a+b;
String d = Double.toString(c);

它返回String。例如，我在a中有0.0，在b中有4.0，它返回0.04.0。

有人可以向我解释为什么以及我应该做些什么呢？

编辑：这是我的代码：

private void WriteMedia(String data) {
    try {
        OutputStreamWriter outputStreamWriter = new OutputStreamWriter(openFileOutput("writemedia.txt", Context.MODE_PRIVATE));
        String zero;
        if(ReadMedia().isEmpty() == true)
        {
            zero = "0.0";
            outputStreamWriter.write(zero);
        }
        else {zero = ReadMedia();}
        double a = Double.parseDouble(zero);
        double b = Double.parseDouble(data);
        double c = a+b;
        String d = Double.toString(c);
        outputStreamWriter.write(d);

        outputStreamWriter.close();


    } catch (IOException e) {
        Log.e("Exception", "File write failed: " + e.toString());
    }
}


private String ReadMedia() {


    String ret = "";

    try {
        InputStream inputStream = openFileInput("writemedia.txt");

        if (inputStream != null) {
            InputStreamReader inputStreamReader = new InputStreamReader(inputStream);
            BufferedReader bufferedReader = new BufferedReader(inputStreamReader);
            String receiveString = "";
            StringBuilder stringBuilder = new StringBuilder();

            while ((receiveString = bufferedReader.readLine()) != null) {
                stringBuilder.append(receiveString);
            }

            inputStream.close();
            ret = stringBuilder.toString();
        }
    } catch (FileNotFoundException e) {
        Log.e("login activity", "File not found: " + e.toString());
    } catch (IOException e) {
        Log.e("login activity", "Can not read file: " + e.toString());
    }

    return ret;
}
private void writeToFile(String data) {
    try {
        OutputStreamWriter outputStreamWriter = new OutputStreamWriter(openFileOutput("estrela.txt", Context.MODE_PRIVATE));
        outputStreamWriter.write(data);
        outputStreamWriter.close();
        WriteMedia(data);

    } catch (IOException e) {
        Log.e("Exception", "File write failed: " + e.toString());
    }
}


private String readFromFile() {

    String ret = "";

    try {
        InputStream inputStream = openFileInput("estrela.txt");

        if (inputStream != null) {
            InputStreamReader inputStreamReader = new InputStreamReader(inputStream);
            BufferedReader bufferedReader = new BufferedReader(inputStreamReader);
            String receiveString = "";
            StringBuilder stringBuilder = new StringBuilder();

            while ((receiveString = bufferedReader.readLine()) != null) {
                stringBuilder.append(receiveString);
            }

            inputStream.close();
            ret = stringBuilder.toString();
        }
    } catch (FileNotFoundException e) {
        Log.e("login activity", "File not found: " + e.toString());
    } catch (IOException e) {
        Log.e("login activity", "Can not read file: " + e.toString());
    }
    WriteMedia(ret);
    return ret;
}

数据是评级栏，零是＆＃34; 0＆＃34;当我启动应用程序时，它应该将评级栏保存到＆＃34;增加＆＃34;（不知道英文单词）。我觉得这很容易但是因为就像我的错误一样，我会把标签安装在android工作室。

以下是我称之为方法的地方：

        button.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            rating = ratingbar.getRating();
            writeToFile(Double.toString(rating));

            writeMyArray(Double.parseDouble(readFromFile()));
            writeMyArray(ratingbar.getRating());
            button.setText(getText(R.string.obrigado) + "!" + readFromFile() + " " + media(arraydays)  + " " + ReadMedia());

        }
    });

它返回＆＃34; 0.0＆＃34;和评级栏在一起，例如：＆＃34; 0.05.0＆＃34;

Answer 1

您的问题不与类型相关（您猜不到），并且您最初发布的代码中的不是。

相反，您只需将 2 数字写入输出流。以下代码写入0.0：

    if(ReadMedia().isEmpty() == true)
    {
        zero = "0.0";
        outputStreamWriter.write(zero);
    }

并且，在添加中，以下代码会写出实际想要的结果：

    double a = Double.parseDouble(zero);
    double b = Double.parseDouble(data);
    double c = a+b;
    String d = Double.toString(c);
    outputStreamWriter.write(d);

JAVA：Double.parseDouble + Double.parseDouble = String

1 个答案: