Java android openFileOutput 有什么问题？
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android what is wrong with openFileOutput?
提问by Fabien
I'm trying to use openFileOutput function but it doesn't compile and doesn't recognize the function. I'm using android sdk 1.6. Is this a sdk problem ? Is this a parameter problem ?
我正在尝试使用 openFileOutput 函数，但它无法编译并且无法识别该函数。我正在使用 android sdk 1.6。这是sdk问题吗？这是参数问题吗？
import java.io.FileOutputStream;
public static void save(String filename, MyObjectClassArray[] theObjectAr) {
FileOutputStream fos;
try {
fos = openFileOutput(filename, Context.MODE_PRIVATE);
ObjectOutputStream oos = new ObjectOutputStream(fos);
oos.writeObject(theObjectAr);
oos.close();
} catch (FileNotFoundException e) {
e.printStackTrace();
}catch(IOException e){
e.printStackTrace();
}
}
采纳答案by naikus
Your method should be as follows. Takes in an extra Context as a parameter. To this method you can pass your Service or Activity
你的方法应该如下。接受一个额外的 Context 作为参数。您可以通过此方法传递您的服务或活动
public static void save(String filename, MyObjectClassArray[] theObjectAr,
Context ctx) {
FileOutputStream fos;
try {
fos = ctx.openFileOutput(filename, Context.MODE_PRIVATE);
ObjectOutputStream oos = new ObjectOutputStream(fos);
oos.writeObject(theObjectAr);
oos.close();
} catch (FileNotFoundException e) {
e.printStackTrace();
}catch(IOException e){
e.printStackTrace();
}
}
回答by Konstantin Burov
You're trying invoke non-static method from static context (your method has static modifier). You either have to make your method to be non-static or to pass in an instance of Context (activity instance in most cases) and invoke the method on the object.
您正在尝试从静态上下文调用非静态方法（您的方法具有静态修饰符）。您要么必须使您的方法为非静态方法，要么传入一个 Context 实例（在大多数情况下为活动实例）并在对象上调用该方法。
回答by phyatt
Also you can't openOutputStreamon a path. It causes this exception:
你也不能openOutputStream在路上。它导致此异常：
java.lang.IllegalArgumentException: File /storage/sdcard0/path/to/file.txt contains a path separator
To fix this you need to create a file object and just create it like this:
要解决这个问题，您需要创建一个文件对象，然后像这样创建它：
String filename = "/sdcard/path/to/file.txt";
File sdCard = Environment.getExternalStorageDirectory();
filename = filename.replace("/sdcard", sdCard.getAbsolutePath());
File tempFile = new File(filename);
try
{
FileOutputStream fOut = new FileOutputStream(tempFile);
// fOut.write();
// fOut.getChannel();
// etc...
fOut.close();
}catch (Exception e)
{
Log.w(TAG, "FileOutputStream exception: - " + e.toString());
}
