读取和写入文件-Java和android
我试图用android将数据保存到一个文件中,但我似乎无法发现我的错误,我也试图读取它 概述: 我有两个按钮和编辑文本 我在编辑文本中键入一些内容,然后按“保存”按钮保存到文件(保存到文件功能)。 当我按下“读取”按钮(读取文件功能)时,我得到了类似于B[]@3213的结果 我从一开始就学习了android教程 我的代码:读取和写入文件-Java和android,java,android,file,Java,Android,File,我试图用android将数据保存到一个文件中,但我似乎无法发现我的错误,我也试图读取它 概述: 我有两个按钮和编辑文本 我在编辑文本中键入一些内容,然后按“保存”按钮保存到文件(保存到文件功能)。 当我按下“读取”按钮(读取文件功能)时,我得到了类似于B[]@3213的结果 我从一开始就学习了android教程 我的代码: package com.keddy.filetesting; import android.app.Activity; import android.content.Con
package com.keddy.filetesting;
import android.app.Activity;
import android.content.Context;
import android.os.Bundle;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.widget.EditText;
import java.io.FileInputStream;
import java.io.FileOutputStream;
public class MainActivity extends Activity {
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
}
@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);
}
public void save_to_file(View view){
try{
String filename = "Myfile.txt";
EditText buffer= (EditText)findViewById(R.id.editText);
String pureText= buffer.getText().toString();
pureText += '\n';
FileOutputStream fos = openFileOutput(filename , Context.MODE_APPEND);
fos.write(pureText.getBytes());
fos.close();
}catch(Exception e){
e.printStackTrace();
}
}
public void read_file(View view){
try
{
String filename = "Myfile.txt";
FileInputStream fis = openFileInput(filename);
int len = fis.read();
byte[] buff = new byte[len];
fis.read(buff,0,len);
EditText changeText = (EditText)findViewById(R.id.editText);
changeText.setText(buff.toString());
}catch(Exception e){
e.printStackTrace();
}
}
}
我似乎无法发现我的错误,因为我非常仔细地遵循了教程,可能是我的问题在于阅读吗?阅读没有问题-您只是调用缓冲区对象本身的toString()方法。这将不会输出其内容,而是输出其内存地址 请尝试拨打:
changeText.setText(new String(buff));
此外,考虑转换过程中的潜在字符集(见)。如果您的文件很大,请不要立即读取缓冲区,并使用a来连接读数。
感谢您的帮助和友好,我一直在为此绞尽脑汁,我是Java新手。public void save_to_file() throws Exception
{
FileOutputStream fos = null;
try
{
String filename = "Myfile.txt";
EditText buffer= (EditText)findViewById(R.id.editText);
String pureText= buffer.getText().toString()
pureText += "\n"; // double-quote
FileOutputStream fos = openFileOutput(filename , Context.MODE_APPEND);
fos.write(pureText);
// call 'flush' and 'close' in the finally clause
}
catch(Exception e)
{
throw e;
//e.printStackTrace();
}
finally
{
if(fos != null)
{
try
{
fos.flush();
}
catch(Exception e)
{
throw e;
}
finally
{
try
{
fos.close();
}
catch(Exception e)
{
throw e;
}
}
}
}
}
public void read_file() throws Exception
{
FileReader fileReader = null;
try
{
String filename = "Myfile.txt";
fileReader = new FileReader( openFileInput(filename) );
StringWriter stringWriter = new StringWriter();
int len = -1;
char[] buff = new char[512];
while((len = fix.read(buff)) != -1)
stringWriter.write(buff,0,len);
String fileContents = stringWriter.toString();
EditText changeText = (EditText)findViewById(R.id.editText);
changeText.setText(fileContents);
}
catch(Exception e)
{
throw e;
//e.printStackTrace();
}
finally
{
if(fileReader != null)
{
try
{
fileReader.close();
}
catch(Exception e)
{
throw e
}
}
}
}