Question

我正在读取一个文本文件并检查空列，但是null检查不起作用，我得到了ArrayIndexOutOfBound异常。

我正在阅读像这样的文本文件

fstream17 = new FileInputStream(
                    Environment.getExternalStorageDirectory() + "/InputFiles"
                            + "/XYZ.TXT");
            in17 = new DataInputStream(fstream17);
            buffreader17 = new BufferedReader(new UnicodeReader(in17));

            while ((strRead = buffreader17.readLine()) != null) {
                splitarray = strRead.split("\t");
                Log.d("Split array", ""+splitarray[0]/*+""+splitarray[11]*/);

                if(splitarray[8] == null || splitarray[8].length() == 0) //Checking for null coloumn 
                {
                    Log.d("Null", "Null");
                }

我的UnicodeReader类看起来像这样。

public class UnicodeReader extends Reader
{
    private static final int BOM_MAX_SIZE = 4;

    private InputStreamReader delegate;

    public UnicodeReader(InputStream in) throws IOException {
        init(in, null);
    }

private void init(InputStream in, String defaultEnc) throws IOException {
        String encoding;
        byte bom[] = new byte[BOM_MAX_SIZE];
        int n, unread;
        PushbackInputStream internalIn = new PushbackInputStream(in, BOM_MAX_SIZE);
        n = internalIn.read(bom, 0, bom.length);

        if ((bom[0] == (byte) 0xEF) && (bom[1] == (byte) 0xBB) && (bom[2] == (byte) 0xBF)) {
            encoding = "UTF-8";
            unread = n - 3;
        }
        else
            if ((bom[0] == (byte) 0xFE) && (bom[1] == (byte) 0xFF)) {
                encoding = "UTF-16BE";
                unread = n - 2;
            }
            else
                if ((bom[0] == (byte) 0xFF) && (bom[1] == (byte) 0xFE)) {
                    encoding = "UTF-16LE";
                    unread = n - 2;
                }
                else
                    if ((bom[0] == (byte) 0x00) && (bom[1] == (byte) 0x00) && (bom[2] == (byte) 0xFE) && (bom[3] == (byte) 0xFF)) {
                        encoding = "UTF-32BE";
                        unread = n - 4;
                    }
                    else
                        if ((bom[0] == (byte) 0xFF) && (bom[1] == (byte) 0xFE) && (bom[2] == (byte) 0x00) && (bom[3] == (byte) 0x00)) {
                            encoding = "UTF-32LE";
                            unread = n - 4;
                        }
                        else {
                            // Unicode BOM mark not found, unread all bytes
                            encoding = defaultEnc;
                            unread = n;
                        }

        if (unread > 0)
            internalIn.unread(bom, (n - unread), unread);
        else
            if (unread < -1)
                internalIn.unread(bom, 0, 0);

        // Use BOM or default encoding
        if (encoding == null) {
            delegate = new InputStreamReader(internalIn);
        }
        else {
            delegate = new InputStreamReader(internalIn, encoding);
        }
    }

但是这个检查现在不起作用，我现在得到的是ArrayIndexOutOfBound异常。

Answer 1

使用：

if(splitarray == null || splitarray.length >= 8) //Checking for null coloumn 
{  
  Log.d("Null", "Null"); 
}

或者为了更安全，当你使用split时，数组的长度是根据你的字符串定义的。因此你不必对元素进行空检查。只需使用.length获取数组的长度，就可以了。

为什么String Array null检查不起作用？

1 个答案: