Question

可能重复：
How to create a Java String from the contents of a file

我正在创建一个java程序来读取文件并创建文件以获得乐趣。我想知道如何从文件中读取并将其设置为字符串变量。或者将扫描仪变量转换为字符串变量，并将编码的一部分作为示例：

    private Scanner x;
    private JLabel label;
    private String str;

    public void openfile(String st){


        try{
            x = new Scanner(new File(st));
        }
        catch(Exception e){
            System.out.println("Error: File Not Found");
        }
    }

Answer 1

这是一个强大的oneliner。

String contents = new Scanner(file).useDelimiter("\\Z").next();

Answer 2

很好的方法是使用Apache commons IOUtils将inputStream复制到StringWriter ......类似

StringWriter writer = new StringWriter();
IOUtils.copy(inputStream, writer, encoding);
String theString = writer.toString();

或者，如果您不想混合Streams和Writers，可以使用ByteArrayOutputStream

http://commons.apache.org/io/api-1.4/org/apache/commons/io/IOUtils.html#toString%28java.io.InputStream,%20java.lang.String%29

Answer 3

或者你甚至可以试试这个：

 ArrayList <String> theWord = new ArrayList <String>();
            //while it has next ..
            while(x.hasNext()){
                //Initialise str with word read
                String str=x.next();
                //add to ArrayList
                theWord.add(str);

            }
            //print the ArrayList
            System.out.println(theWord);

        }

Answer 4

以下是如何将文件读入字符串的示例：

public String readDocument(File document)
        throws SystemException {
    InputStream is = null;
    try {
        is = new FileInputStream(document);
        long length = document.length();
        byte[] bytes = new byte[(int) length];
        int offset = 0;
        int numRead = 0;
        while (offset < bytes.length && (numRead = is.read(bytes, offset, bytes.length - offset)) >= 0) {
            offset += numRead;
        }
        if (offset < bytes.length) {
            throw new SystemException("Could not completely read file: " + document.getName());
        }
        return new String(bytes);
    } catch (FileNotFoundException e) {
        LOGGER.error("File not found exception occurred", e);
        throw new SystemException("File not found exception occurred.", e);
    } catch (IOException e) {
        LOGGER.error("IO exception occurred while reading file.", e);
        throw new SystemException("IO exception occurred while reading file.", e);
    } finally {
        if (is != null) {
            try {
                is.close();
            } catch (IOException e) {
                LOGGER.error("IO exception occurred while closing stream.", e);
            }
        }
    }
}

Answer 5

BufferedReader in =new BufferedReader(new FileReader(filename));
    String strLine;
    while((strLine=in.readLine())!=null){
    //do whatever you want with that string here
    }

Java：转换问题

5 个答案: