一种方法是让您添加到 ArrayList 的类实现可序列化。如果您的类仅由也实现可序列化的对象组成，那么您就完成了（很可能是这种情况），只需像这样添加实现可序列化：
public class myClass implements Serializable {
否则，您将需要将以下两个方法添加到您的课程中
private void writeObject(java.io.ObjectOutputStream out) throws IOException
private void readObject(java.io.ObjectInputStream in) throws IOException, ClassNotFoundException
添加实现 Serialible 让 ObjectOutStream 知道它可以序列化您的数据以进行存储：
然后，您可以实现以下方法来保存和打开您的数据，请参阅每个步骤的注释...
void saveArray(String filename, ArrayList<myClass> arrayToSave) {
FileOutputStream fos; //creates a file output stream to save your data
ObjectOutputStream oos; //creates an object output stream to serialize your data
try {
fos = openFileOutput(filename, Context.MODE_PRIVATE); //creates and opens file with the specified filename, Context.MODE_PRIVATE limits its visibility to your app, other modes are available
oos = new ObjectOutputStream(fos); //connects object output to file output
oos.writeObject(arrayToSave); //writes the object to the file
}
catch (FileNotFoundException e) {
//handle file not found
}
catch (IOException e) {
}
//handle I/O execption
oos.close(); //close object output stream
fos.close(); //close file output stream
}
ArrayList<myClass> openArray (String filename) {
ArrayList<myClass> array = null; //create ArrayList
FileInputStream fis; //create fileinput stream
ObjectInputStream ois; //create objet input stream
try {
fis = openFileInput(filename); //open file stream
ois = new ObjectInputStream(fis); //open object stream
array = (ArrayList<myClass>)ois.readObject(); //create object from stream
}
catch (Exception e) {
System.out.println(e.toString());
}
ois.close(); //close objectinput stream
fis.close(); //close fileinput stream
return array;
}
最后，两个文件输入/输出流都可以包装在缓冲输入流/缓冲输出流中，但我发现对于小文件，它不会对性能产生太大影响。这可以通过
BufferedInputStream bufIn = new BufferedInputStream(new FileInputStream("file.java"));
BufferedOutputStream bufOut = new BufferedOutputStream(new FileInputStream("file.java"));
好的，下面是一个完整的活动文件来演示这一点，并且已经用 2.1 版进行了测试...您唯一需要更改的是包名称以匹配您的项目...请注意，这会将 saveData 中的变量更改为 package from私有的，如果你想让它们保持私有，你可能应该这样做，你需要实现 setter/getter，但是下面的代码应该可以帮助你理解保存/加载对象......
package youpackage.name.myapp;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.io.Serializable;
import java.util.ArrayList;
import android.app.Activity;
import android.content.Context;
import android.os.Bundle;
class saveData implements Serializable {
private static final long serialVersionUID = 1L;
private final int version = 101002;
String title;
int[] Int1 = new int[3];
int[] Int2 = new int[3];
int[] Int3 = new int[3];
int Int;
}
public class MyAppActivity extends Activity {
/** Called when the activity is first created. */
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
System.out.println("This next line creates instance of class to save");
saveData mySaveData = new saveData();
System.out.println("This next line sets the title...");
mySaveData.title = "accept my answer...";
ArrayList<saveData> myArrayList = new ArrayList<saveData>();
System.out.println("This next line adds the object to the ArrayList");
myArrayList.add(mySaveData);
System.out.println("This next line saves the arraylist");
saveArray("myFilename", myArrayList);
System.out.println("This next line loads the arraylist back...");
ArrayList<saveData> retrieveArrayList = openArray("myFilename");
if (retrieveArrayList.size() > 0) {
saveData retrievedSaveData = retrieveArrayList.get(0);
System.out.println("if successful, the title set above will appear...");
System.out.println("if save/retrieve works, then " + retrievedSaveData.title);
}
else {
System.out.println("it did not work");
}
}
void saveArray(String filename, ArrayList<saveData> arrayToSave) {
FileOutputStream fos;
ObjectOutputStream oos;
try {
fos = openFileOutput(filename, Context.MODE_PRIVATE);
oos = new ObjectOutputStream(fos);
oos.writeObject(arrayToSave);
oos.close();
fos.close();
} catch (Exception e) {
System.out.println(e.toString());
}
}
ArrayList<saveData> openArray (String filename) {
ArrayList<saveData> array = null;
FileInputStream fis;
ObjectInputStream ois;
try {
fis = openFileInput(filename);
ois = new ObjectInputStream(fis);
array = (ArrayList<saveData>)ois.readObject();
ois.close();
fis.close();
} catch (Exception e) {
System.out.println(e.toString());
}
return array;
}
}
正如我在上一篇文章中提到的，以下更新的加载和保存方法提高了性能......
void saveArray2(String filename, ArrayList<saveData> arrayToSave) {
try {
BufferedOutputStream bos = new BufferedOutputStream(openFileOutput(filename, Context.MODE_PRIVATE),8000);
ObjectOutputStream oos = new ObjectOutputStream(bos);
oos.writeObject(arrayToSave);
oos.close();
} catch (Exception e) {
System.out.println(e.toString());
}
}
ArrayList<saveData> openArray2 (String filename) {
ArrayList<saveData> array = null;
try {
BufferedInputStream bufIn = new BufferedInputStream(openFileInput(filename),8000);
ObjectInputStream ois = new ObjectInputStream(bufIn);
array = (ArrayList<saveData>)ois.readObject();
ois.close();
} catch (Exception e) {
System.out.println(e.toString());
}
return array;
}