应用程序从文件中读取文本并在文本字段上打印

Question

I think my code is reading the file right, but when I run the app, the output is "Hello World". Which tells me that the text field isn't getting overwritten. I think the problem lies in the while loop. Here is my java code:

package com.example.fileio.app1_fileio;

import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.util.Log;
import android.view.Menu;
import android.view.MenuItem;
import android.widget.TextView;

import java.io.BufferedReader;
import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.util.List;
import java.util.Scanner;
import java.io.FileReader;


public class MainActivity extends AppCompatActivity {

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

    BufferedReader br = null;

    try {

        String sCurrentLine;

        //get a reference to the textview in the view, this is done by referring to the textview's id: outputText
        TextView t = (TextView) findViewById(R.id.textField);


        String var1;
        String var2;

        br = new BufferedReader(new FileReader("C:\\Users\\android.txt"));

        while ((sCurrentLine = br.readLine()) != null) {
            var1 = sCurrentLine;
            var2 = sCurrentLine;
            //overwrite the text in the textview
            t.setText(var1);
        }

    } catch (IOException e) {
        e.printStackTrace();
    } finally {
        try {
            if (br != null)br.close();
        } catch (IOException ex) {
            ex.printStackTrace();
        }
    }


    //create a new file using the utility class: "FileUtility"
    FileUtility myFile = new FileUtility();

    Log.i("Info", "Android File Example Main Activity Completed");

}

@Override
public boolean onCreateOptionsMenu(Menu menu) {
    // Inflate the menu; this adds items to the action bar if it is present.
    getMenuInflater().inflate(R.menu.menu_main, menu);
    return true;
}

@Override
public boolean onOptionsItemSelected(MenuItem item) {
    // Handle action bar item clicks here. The action bar will
    // automatically handle clicks on the Home/Up button, so long
    // as you specify a parent activity in AndroidManifest.xml.
    int id = item.getItemId();

    //noinspection SimplifiableIfStatement
    if (id == R.id.action_settings) {
        return true;
    }

    return super.onOptionsItemSelected(item);
}

}

<TextView android:text="@string/hello_world" android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:id="@+id/textField" />

Answer 1

If you want to read in a text file and then update a TextView with the contents of the text file, you could try this.

First, add the text file to your project in the "raw" folder of your res folder. If you don't have a raw folder, you can add one by right clicking on your res folder and selecting New->Android Resource Directory. Then in the next dialog you would select "raw" from the "Resource Type" drop down. Name the new directory "raw" click OK to create it.

Once your raw folder is created, simply place your text file into this folder.

Now that your text file is part of your project, you can read it and update a TextView with the context doing something like this:

StringBuilder stringBuilder = new StringBuilder();
InputStream inputStream = getResources().openRawResource(R.raw.your_text_file);
BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(inputStream));
String line;

try {
    while ((line = bufferedReader.readLine()) != null) {
        stringBuilder.append(line).append("\n");
    }

    bufferedReader.close();

} catch (IOException ioe) {
    ioe.printStackTrace();
}

TextView textView = (TextView) findViewById(R.id.your_text_view);
textView.setText(stringBuilder.toString());