Wie fügen Sie die Daten in eine Datei in android

Kann mir jemand sagen, wie Anhängen von Daten an eine Datei, die bereits Daten in Android?

Ich schrieb einige code, aber es funktioniert nicht. Dies ist meine Aktivität:

package updatefile.developer.com.updatefiledemo;

import android.support.v7.app.ActionBarActivity;
import android.os.Bundle;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.widget.Button;
import android.widget.Toast;

import java.io.BufferedWriter;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.FileWriter;
import java.io.IOException;
import java.io.OutputStreamWriter;
import java.io.PrintStream;
import java.nio.Buffer;

public class MainActivity extends ActionBarActivity {
    Button create,update;
    String data = "This is a sample";
    File file;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        create = (Button)findViewById(R.id.btn_create);
        create.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                File folder = new File("/sdcard/demo");
                folder.mkdirs();
                file = new File("/sdcard/demo/demotext.txt");
                try {
                    FileOutputStream fileinput = new FileOutputStream(file);
                    PrintStream printstream = new PrintStream(fileinput);
                    printstream.print(data+"\n");
                    fileinput.close();
                } catch (Exception e) {
                    Toast.makeText(MainActivity.this,e.getMessage(),Toast.LENGTH_SHORT).show();
                }
            }
        });

        update = (Button)findViewById(R.id.btn_update);
        update.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                if(!file.exists()) {
                    try {
                        file.createNewFile();
                    } catch (Exception e) {
                        Toast.makeText(MainActivity.this,e.getMessage(),Toast.LENGTH_SHORT).show();
                    }
                }

                try {
                    OutputStreamWriter file_writer = new OutputStreamWriter(new FileOutputStream(file,true));
                    BufferedWriter buffered_writer = new BufferedWriter(file_writer);
                    buffered_writer.write("This is a appended text");
                    buffered_writer.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
        });
    }

    @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);
    }
}

finden Sie hier stackoverflow.com/questions/4542318/android-append-text-file

InformationsquelleAutor RD Division Medequip | 2015-03-25

23

FileOutputStream fileinput = new FileOutputStream(file, true);

War es ein einfacher Fehler, weil die Einstellung nicht Anhängen Flagge zu true. Nur setzen Sie ihn auf true.

Ist das Standardverhalten überschreiben der Inhalt der Datei 🙂

Danke dude, es funktioniert wie Charme und ich Platz in FileOutputStream fileinput = new FileOutputStream(Datei,true);Danke für die Antwort dude

InformationsquelleAutor MeshBoy
5

Das einzige, was Sie tun müssen ist, fügen Sie einfach ein "true" to FileOutputStream wie
```
FileOutputStream fileinput = new FileOutputStream(file,true);
```
Hier ist die Dokumentation

Baut eine neue FileOutputStream schreibt in eine Datei. Wenn append
stimmt und die Datei bereits existiert, wird Sie angehängt werden; ansonsten
abgeschnitten wird. Die Datei wird erstellt falls Sie nicht vorhanden ist.

InformationsquelleAutor Don Chakkappan

File file = new File(path);
        if (!file.exists()) {
            try {
                file.createNewFile();
            } catch (IOException ioe) {
                ioe.printStackTrace();
            }
        }
        try {
            FileOutputStream fileOutputStream = new FileOutputStream(file);
            OutputStreamWriter writer = new OutputStreamWriter(fileOutputStream);
            writer.append(data);
            writer.close();
            fileOutputStream.close();
        } catch (FileNotFoundException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }

InformationsquelleAutor

import java.io.BufferedReader;
import java.io.File;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.PrintWriter;
import android.app.Activity;
import android.os.Bundle;
import android.os.Environment;
import android.util.Log;
import android.widget.TextView;

 public class WriteSDCard extends Activity {

 private static final String TAG = "MEDIA";
 private TextView tv;

  /** Called when the activity is first created. */
@Override
 public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.main);     
    tv = (TextView) findViewById(R.id.TextView01);
    checkExternalMedia();
    writeToSDFile();
    readRaw();
 }

/** Method to check whether external media available and writable. This is adapted from
   http://developer.android.com/guide/topics/data/data-storage.html#filesExternal */

 private void checkExternalMedia(){
      boolean mExternalStorageAvailable = false;
    boolean mExternalStorageWriteable = false;
    String state = Environment.getExternalStorageState();

    if (Environment.MEDIA_MOUNTED.equals(state)) {
        //Can read and write the media
        mExternalStorageAvailable = mExternalStorageWriteable = true;
    } else if (Environment.MEDIA_MOUNTED_READ_ONLY.equals(state)) {
        //Can only read the media
        mExternalStorageAvailable = true;
        mExternalStorageWriteable = false;
    } else {
        //Can't read or write
        mExternalStorageAvailable = mExternalStorageWriteable = false;
    }   
    tv.append("\n\nExternal Media: readable="
            +mExternalStorageAvailable+" writable="+mExternalStorageWriteable);
}

/** Method to write ascii text characters to file on SD card. Note that you must add a 
   WRITE_EXTERNAL_STORAGE permission to the manifest file or this method will throw
   a FileNotFound Exception because you won't have write permission. */

private void writeToSDFile(){

    //Find the root of the external storage.
    //See http://developer.android.com/guide/topics/data/data-  storage.html#filesExternal

    File root = android.os.Environment.getExternalStorageDirectory(); 
    tv.append("\nExternal file system root: "+root);

    //See http://stackoverflow.com/questions/3551821/android-write-to-sd-card-folder

    File dir = new File (root.getAbsolutePath() + "/download");
    dir.mkdirs();
    File file = new File(dir, "myData.txt");

    try {
        FileOutputStream f = new FileOutputStream(file);
        PrintWriter pw = new PrintWriter(f);
        pw.println("Hi , How are you");
        pw.println("Hello");
        pw.flush();
        pw.close();
        f.close();
    } catch (FileNotFoundException e) {
        e.printStackTrace();
        Log.i(TAG, "******* File not found. Did you" +
                " add a WRITE_EXTERNAL_STORAGE permission to the   manifest?");
    } catch (IOException e) {
        e.printStackTrace();
    }   
    tv.append("\n\nFile written to "+file);
}

/** Method to read in a text file placed in the res/raw directory of the application. The
  method reads in all lines of the file sequentially. */

private void readRaw(){
    tv.append("\nData read from res/raw/textfile.txt:");
    InputStream is = this.getResources().openRawResource(R.raw.textfile);
    InputStreamReader isr = new InputStreamReader(is);
    BufferedReader br = new BufferedReader(isr, 8192);    //2nd arg is buffer size

    //More efficient (less readable) implementation of above is the composite expression
    /*BufferedReader br = new BufferedReader(new InputStreamReader(
            this.getResources().openRawResource(R.raw.textfile)), 8192);*/

    try {
        String test;    
        while (true){               
            test = br.readLine();   
            //readLine() returns null if no more lines in the file
            if(test == null) break;
            tv.append("\n"+"    "+test);
        }
        isr.close();
        is.close();
        br.close();
    } catch (IOException e) {
        e.printStackTrace();
    }
    tv.append("\n\nThat is all");
}
}

also add below permission in manifeast file
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"/>

InformationsquelleAutor Alka Jadav

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