Question

我正在使用此代码：

// Open your local db as the input stream
    InputStream myInput = null;
    try {
        myInput = this.getAssets().open("Student info.txt");


    // Path to the just created empty db
    String outFileName =Environment.getExternalStorageDirectory().getAbsolutePath() + "/Student info.txt";

    // Open the empty db as the output stream
    OutputStream myOutput = new FileOutputStream(outFileName);
    // transfer bytes from the inputfile to the outputfile

    byte[] buffer = new byte[1024];
    int length;
    while ((length = myInput.read(buffer)) > 0) {
        myOutput.write(buffer, 0, length);
    }
    // Close the streams
    myOutput.flush();
    myOutput.close();
    myInput.close();
        Toast.makeText(getBaseContext(), "Done", Toast.LENGTH_SHORT).show();
    } catch (IOException e) {
        e.printStackTrace();
    }

将资产文件夹中的文件复制到我的SD卡。现在我需要的是，如果sdcard中的文件是空的，那么继续并从资产复制到SD卡。否则，如果SD卡中的文件不为空，请不要复制任何内容。我怎么能做到这一点？谢谢

Answer 1

如果文件存在且不为空，则运行上面的代码

 String outFileName =
`Environment.getExternalStorageDirectory().getAbsolutePath() + "/Student info.txt"`;
File f = new File(outFileName);

           if (f.length() == 0) {
                Toast.makeText(this, "File does not Exists or empty", Toast.LENGTH_SHORT).show();

            } else {
                Toast.makeText(this, "Exists and is not empty", Toast.LENGTH_SHORT).show();
            }

OR

File f = new File(outFileName);

        if(f.exists()){
            //File exist
            if (f.length() == 0) {
                Toast.makeText(this, "File empty", Toast.LENGTH_SHORT).show();

            } else {
                Toast.makeText(this, "File is not empty", Toast.LENGTH_SHORT).show();
            }
        }else {
            Toast.makeText(this, "File does not exist", Toast.LENGTH_SHORT).show();
        }

将文件从资产复制到仅在非空时才会被吓到

1 个答案: