我有一个当前正在扩展Activity的类，我有onCreate（），OnBackPress（）等方法。我想把它变成一个独立的类，但所有上面的方法都是未定义的。问题是什么？难道不能导入这些课程吗？例如，我为findViewById导入android.view.View但它仍然没有区别。请指教。
File_Explore
public class File_Explorer extends Activity {
// Stores names of traversed directories
ArrayList<String> str = new ArrayList<String>();
// Check if the first level of the directory structure is the one showing
private Boolean firstLvl = true;
String aDataRow = "";
static StringBuilder aBuffer = new StringBuilder();
String aBuffer1="";
private static final String TAG = "F_PATH";
static long fileSizeInMB;
private Item[] fileList;
private File path = new File(Environment.getExternalStorageDirectory().getAbsolutePath());
private String chosenFile;
private static final int DIALOG_LOAD_FILE = 0;
static String fileExtension="";
ListAdapter adapter;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
loadFileList();
showDialog(DIALOG_LOAD_FILE);
Log.d(TAG, path.getAbsolutePath());
}
private void loadFileList() {
try {
path.mkdirs();
} catch (SecurityException e) {
Log.e(TAG, "unable to write on the sd card ");
}
// Checks whether path exists
if (path.exists()) {
FilenameFilter filter = new FilenameFilter() {
@Override
public boolean accept(File dir, String filename) {
File sel = new File(dir, filename);
// Filters based on whether the file is hidden or not
return (sel.isFile() || sel.isDirectory())
&& !sel.isHidden();
}
};
String[] fList = path.list(filter);
fileList = new Item[fList.length];
for (int i = 0; i < fList.length; i++) {
fileList[i] = new Item(fList[i], R.drawable.ic_launcher);
// Convert into file path
File sel = new File(path, fList[i]);
// Set drawables
if (sel.isDirectory()) {
fileList[i].icon = R.drawable.ic_launcher;
Log.d("DIRECTORY", fileList[i].file);
} else {
Log.d("FILE", fileList[i].file);
}
}
if (!firstLvl) {
Item temp[] = new Item[fileList.length + 1];
for (int i = 0; i < fileList.length; i++) {
temp[i + 1] = fileList[i];
}
temp[0] = new Item("Back", R.drawable.ic_launcher);
fileList = temp;
}
} else {
Log.e(TAG, "path does not exist");
}
adapter = new ArrayAdapter<Item>(this,
android.R.layout.select_dialog_item, android.R.id.text1,
fileList) {
@Override
public View getView(int position, View convertView, ViewGroup parent) {
// creates view
View view = super.getView(position, convertView, parent);
TextView textView = (TextView) view
.findViewById(android.R.id.text1);
// put the image on the text view
textView.setCompoundDrawablePadding(
fileList[position].icon);
return view;
}
};
}
private class Item {
public String file;
public int icon;
public Item(String file, Integer icon) {
this.file = file;
this.icon = icon;
}
@Override
public String toString() {
return file;
}
}
@Override
protected Dialog onCreateDialog(int id) {
Dialog dialog = null;
AlertDialog.Builder builder = new Builder(this);
if (fileList == null) {
Log.e(TAG, "No files loaded");
dialog = builder.create();
return dialog;
}
switch (id) {
case DIALOG_LOAD_FILE:
builder.setTitle("Choose your file");
builder.setAdapter(adapter, new DialogInterface.OnClickListener() {
@Override
public void onClick(DialogInterface dialog, int which) {
chosenFile = fileList[which].file;
File sel = new File(path + "/" + chosenFile);
if (sel.isDirectory()) {
firstLvl = false;
// Adds chosen directory to list
str.add(chosenFile);
fileList = null;
path = new File(sel + "");
loadFileList();
removeDialog(DIALOG_LOAD_FILE);
showDialog(DIALOG_LOAD_FILE);
Log.d(TAG, path.getAbsolutePath());
}
// Checks if 'up' was clicked
else if (chosenFile.equalsIgnoreCase("Back") && !sel.exists()) {
// present directory removed from list
String s = str.remove(str.size() - 1);
// path modified to exclude present directory
path = new File(path.toString().substring(0,
path.toString().lastIndexOf(s)));
fileList = null;
// if there are no more directories in the list, then
// its the first level
if (str.isEmpty()) {
firstLvl = true;
}
loadFileList();
removeDialog(DIALOG_LOAD_FILE);
showDialog(DIALOG_LOAD_FILE);
Log.d(TAG, path.getAbsolutePath());
}
// File picked
else {
// Perform action with file picked
fileExtension
= MimeTypeMap.getFileExtensionFromUrl(sel.toString());
// Toast.makeText(getApplication(), fileExtension, Toast.LENGTH_LONG).show();
long fileSizeInBytes = sel.length();
fileSizeInMB = fileSizeInBytes/(1024*1024);
Toast.makeText(getApplication(), String.valueOf(fileSizeInMB).toString(), Toast.LENGTH_LONG).show();
if(fileSizeInMB >1){
Intent returnIntent = new Intent();
returnIntent.putExtra("name", aBuffer.toString());
setResult(RESULT_OK, returnIntent);
}
else{
try{
// ArrayList<String> MyFiles = new ArrayList<String>();
FileInputStream fIn = new FileInputStream(sel);
BufferedReader myReader = new BufferedReader(
new InputStreamReader(fIn));
while ((aDataRow = myReader.readLine()) != null) {
aBuffer.append(aDataRow.toString()).append("\n");
}
// aBuffer1 = aBuffer.toString();
myReader.close();
}catch (FileNotFoundException e)
{e.printStackTrace();}
catch (IOException e) {
e.printStackTrace();
}
// Toast.makeText(getApplicationContext(),aBuffer,Toast.LENGTH_LONG).show();
Intent returnIntent = new Intent();
returnIntent.putExtra("name", aBuffer.toString());
setResult(RESULT_OK, returnIntent);
finish();
}
}
aBuffer.delete(0, aBuffer.length());
// aBuffer1=null;
}
}
);
break;
}
dialog = builder.show();
return dialog;
}
@Override
public void onBackPressed() {
// TODO Auto-generated method stub
super.onBackPressed();
Intent i= new Intent(this, File_Selecter.class);
startActivity(i);
}
}