我制作了一个用于学习Java的Android应用程序。
现在，我想将包含对象的列表中的对象写入文件。
喜欢......
private List<MyObjects> objects = new ArrayList<MyObjects>();
MyObjects是一个额外的类，实现了“Serializable”。
要在文件中写入对象，我还要使用额外的类。
现在我的问题。
使用下面的行我得到一个FileNotFoundException。
fos = new FileOutputStream(fileName);
当我用这条线改变这条线时......
fos = ctx.openFileOutput(fileName, Context.MODE_PRIVATE);
...看起来很不错但在endig代码后我无法在data / data / myPakage / files /中找到该文件。
该文件不存在。
我在过去的4天里阅读了很多网站和教程，但我找不到我的错误。
请帮助我。
我不需要解码的代码，但是我的错误代码中的右侧链接或指针都可以。
抱歉我的英文。不是我的第一语言。
我不确定您需要哪些代码部分才能获得良好的概述。如果您需要更多，请告诉我。
这是我的主要网站的一部分
package com.example.myProject;
import android.os.Bundle;
import android.app.FragmentTransaction;
import android.support.v4.app.FragmentActivity;
import android.support.v4.view.ViewPager;
public class ActivityMain extends FragmentActivity {
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main_layout_calc);
TabAdapter = new TabPagerAdapter(getSupportFragmentManager());
}
}
我的片段网站的部分内容
package com.example.myProject;
import java.io.File;
import java.util.ArrayList;
import java.util.List;
import android.os.Bundle;
import android.support.v4.app.Fragment;
import android.support.v4.app.FragmentTransaction;
import android.view.LayoutInflater;
import android.view.View;
import android.view.View.OnClickListener;
import android.view.ViewGroup;
import android.widget.Button;
public class Fragment_1 extends Fragment implements OnClickListener {
private Button btnOFF;
private List<Numbers> number = new ArrayList<Numbers>();
private View fragment_1;
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
this.fragment_1 = inflater.inflate(R.layout.fragment_layout, container, false);
this.btnOFF = (Button)elementary.findViewById(R.id.id_btnOFF_Elementary);
this.btnOFF.setOnClickListener(this);
this.number.add(new Numbers());
// Here i try to get my data back from the file.
// Every time i get the information; The file not exist
// Perhaps the "containsAll" are wrong. But this is in the moment not my problem.
this.number.containsAll(StreamControl.importNumbers(this.getActivity()));
return fragment_1;
}
@Override
public void onClick(View buttonView) {
if (buttonView == this.btnOFF) {
// Here i try to export data over extra class -- see below
// I put in my List with objects calls "number" and information
// for "Context" i hope.
StreamControl.exportNumbers(number, this.getActivity());
}
}
}
我班级的部分号码
package com.example.myProject;
import java.io.Serializable;
public class Numbers implements Serializable {
private static final long serialVersionUID = -5384438724532423282L;
.
.
.
}
这里是“in”和“out”文件中的代码
package com.example.myProject;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.util.ArrayList;
import java.util.List;
import android.content.Context;
public class StreamControl {
public static void exportNumbers(List<Numbers> number, Context ctx) {
String fileName = "MyCacheFile.ser";
File cacheFile = new File(fileName);
FileOutputStream fos = null;
try {
// With this line is it not working everytime.
// File not found exception
// But to make my own file with "createNewFile()" is not working
// in data/data i have just read permission.
fos = new FileOutputStream(cacheFile);
// If i use this line i have less problems.
// All Informations "i used Toast on a lot of places" was god.
// But after it, it was nowhere a file to found.
//fos = ctx.openFileOutput(fileName, Context.MODE_PRIVATE);
ObjectOutputStream oos = null;
try {
oos = new ObjectOutputStream(fos);
oos.writeInt(number.size());
for (int i =0; i < number.size(); i++) {
oos.writeObject(new Numbers(((Numbers)number.get(i)).getNumbers()));
}
}
catch (IOException e1) { e1.printStackTrace(); }
finally {
try {
if (oos != null) { oos.close(); }
}
catch (IOException ex) { }
}
}
catch (FileNotFoundException e2) { e2.printStackTrace(); }
finally {
try {
if (fos != null) { fos.close(); }
}
catch (IOException ex) { ex.printStackTrace(); }
}
}
public static List<Numbers> importNumbers(Context ctx) {
String fileName = "MyCacheFile.ser";
int count = 0;
List<Numbers> number = new ArrayList<Numbers>();
FileInputStream fis = null;
try {
fis = new FileInputStream(fileName);
ObjectInputStream ois = null;
try {
ois = new ObjectInputStream(fis);
count = ois.readInt();
for (int i = 0; i < count; i++) {
number.add(new Numbers(((Numbers) ois.readObject()).getNumbers()));
}
}
catch (IOException ex) { ex.printStackTrace(); }
catch (ClassNotFoundException ex) { ex.printStackTrace(); }
finally {
try {
if (ois != null) { ois.close(); }
}
catch (IOException ex) { ex.printStackTrace(); }
}
}
catch (FileNotFoundException ex) { ex.printStackTrace(); }
finally {
try {
if (fis != null) { fis.close(); }
}
catch (IOException ex) { ex.printStackTrace(); }
}
return number;
}
}
所以，我希望这是足够的信息。
我期待