BufferedReader在存储器中找不到文本文件

Question

我遇到了一个问题，BufferedReader无法读取我的文本文件。我尝试显示存储器中的文本文件，但它不显示它。我的系统没有错误...有人能帮帮我吗..。这是我的代码。

[

public class LoadFile extends AppCompatActivity {

    private static final int READ_REQUEST_CODE = 1001;

    Button b_load;
    TextView tv_output;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.load_file);

        b_load = (Button) findViewById(R.id.b_load);
        tv_output = (TextView) findViewById(R.id.tv_output);

        b_load.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                performFileSearch();
            }
        });
    }

问题就在这里..我尝试使用log.e，想看看代码是否可以读取文件。Log.e("okeyy1"，(file + "1"))；可以读取，但Log.e("okeyy12"，(line + "1"))；不能读取任何内容，也不能在longcat中显示。

    //read content of the file
    private String readText(String input, Context context){
        //File file = new File(Environment.getExternalStorageState(), input);
        File sdcard = context.getExternalFilesDir(null);
        File dir = new File(sdcard.getAbsolutePath()+ "/text/");
        File file = new File(dir, input);
        StringBuilder text = new StringBuilder();
        try {
            Log.e("okeyy1", (file + "1"));

            //the problem is here.......
            BufferedReader br = new BufferedReader(new FileReader(file));
            String line;
            line = br.readLine();
            Log.e("okeyy2", (line + "1"));
            //while ((line = br.readLine()) != null){
            while(line != null){
                text.append(line);
                text.append('\n');
            }
            br.close();
        }
        catch (IOException e){
            e.printStackTrace();
        }
        return text.toString();
    }

这是从存储器中选择文本文件的功能

    //select file from storage
    private void performFileSearch(){
        Intent intent = new Intent(Intent.ACTION_OPEN_DOCUMENT);
        intent.addCategory(Intent.CATEGORY_OPENABLE);
        intent.setType("text/*");
        startActivityForResult(intent, READ_REQUEST_CODE);
    }

    protected void onActivityResult(int requestCode, int resultCode, Intent data) {
        super.onActivityResult(requestCode, resultCode, data);
        if (requestCode == READ_REQUEST_CODE && resultCode == Activity.RESULT_OK) {
            if (data != null) {
                Uri uri = data.getData();
                String path = uri.getPath();
                path = path.substring(path.indexOf(":") + 1);
                if (path.contains("emulated")) {
                    path = path.substring(path.indexOf("0") + 1);
                }
                Context context = getApplicationContext();
                Toast.makeText(this, "" + path, Toast.LENGTH_SHORT).show();
                tv_output.setText(readText(path, context));
                Log.e("lol", path);
            }
        }
    }
}

Answer 1

在您的readText()方法中，您读取行的方式

  while(line != null)
  {
       text.append(line);
       text.append('\n');
   }

这将不起作用，因为您没有读取其中的下一行，并且您在外部读取的第一行将永远不会为空，并且您的while循环将永远不会结束。你一直在循环中前进。这是新的代码。

try(BufferedReader br = new BufferedReader(new FileReader(file)))
{
  StringBuilder builder=new StringBuilder();

  String line;
  while((line=reader.readLine())!=null)
  {
   builder.append(line).append("\n");
  }

  return builder;
}
catch(IOException ex){}