Force Close When Attempting to Copy Files Programatically - Android / Java
-
21-12-2019 - |
Question
I'm attempting to copy a file programatically using:
public void function1(int id) {
Toast.makeText(this, "Copy", Toast.LENGTH_SHORT).show();
try {
copyDirectoryOneLocationToAnotherLocation(currentDir, currentDir);
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
public static void copyDirectoryOneLocationToAnotherLocation(
File sourceLocation, File targetLocation) throws IOException {
if (sourceLocation.isDirectory()) {
if (!targetLocation.exists()) {
targetLocation.mkdir();
}
String[] children = sourceLocation.list();
for (int i = 0; i < sourceLocation.listFiles().length; i++) {
copyDirectoryOneLocationToAnotherLocation(new File(
sourceLocation, children[i]), new File(targetLocation,
children[i]));
}
} else {
InputStream in = new FileInputStream(sourceLocation);
OutputStream out = new FileOutputStream(targetLocation);
// Copy the bits from instream to outstream
byte[] buf = new byte[1024];
int len;
while ((len = in.read(buf)) > 0) {
out.write(buf, 0, len);
}
in.close();
out.close();
}
}
However I'm getting an error stating:
FATAL EXCEPTION: main NullPointerException at com.example.project.FileChooser.function1(FileChooser.java:164)
on the line:
copyDirectoryOneLocationToAnotherLocation(currentDir, currentDir);
I think I may have used incorrect paramaters passed in copyDirectoryOneLocationToAnotherLocation
I thought perhaps I should have used: sourceLocation, targetLocation but that did not work for me either.
Logcat:
01-09 15:54:49.026: E/AndroidRuntime(15378): FATAL EXCEPTION: main
01-09 15:54:49.026: E/AndroidRuntime(15378): java.lang.NullPointerException
01-09 15:54:49.026: E/AndroidRuntime(15378): at com.example.project.FileChooser.copyDirectoryOneLocationToAnotherLocation(FileChooser.java:205)
01-09 15:54:49.026: E/AndroidRuntime(15378): at com.example.project.FileChooser.copyDirectoryOneLocationToAnotherLocation(FileChooser.java:207)
01-09 15:54:49.026: E/AndroidRuntime(15378): at com.example.project.FileChooser.function1(FileChooser.java:164)
01-09 15:54:49.026: E/AndroidRuntime(15378): at com.example.project.FileChooser.onContextItemSelected(FileChooser.java:148)
01-09 15:54:49.026: E/AndroidRuntime(15378): at android.app.Activity.onMenuItemSelected(Activity.java:2597)
01-09 15:54:49.026: E/AndroidRuntime(15378): at com.android.internal.policy.impl.PhoneWindow$DialogMenuCallback.onMenuItemSelected(PhoneWindow.java:3663)
01-09 15:54:49.026: E/AndroidRuntime(15378): at com.android.internal.view.menu.MenuBuilder.dispatchMenuItemSelected(MenuBuilder.java:735)
01-09 15:54:49.026: E/AndroidRuntime(15378): at com.android.internal.view.menu.MenuItemImpl.invoke(MenuItemImpl.java:149)
01-09 15:54:49.026: E/AndroidRuntime(15378): at com.android.internal.view.menu.MenuBuilder.performItemAction(MenuBuilder.java:874)
01-09 15:54:49.026: E/AndroidRuntime(15378): at com.android.internal.view.menu.MenuDialogHelper.onClick(MenuDialogHelper.java:167)
01-09 15:54:49.026: E/AndroidRuntime(15378): at com.android.internal.app.AlertController$AlertParams$3.onItemClick(AlertController.java:963)
01-09 15:54:49.026: E/AndroidRuntime(15378): at android.widget.AdapterView.performItemClick(AdapterView.java:298)
01-09 15:54:49.026: E/AndroidRuntime(15378): at android.widget.AbsListView.performItemClick(AbsListView.java:1128)
01-09 15:54:49.026: E/AndroidRuntime(15378): at android.widget.AbsListView$PerformClick.run(AbsListView.java:2812)
01-09 15:54:49.026: E/AndroidRuntime(15378): at android.widget.AbsListView$1.run(AbsListView.java:3571)
01-09 15:54:49.026: E/AndroidRuntime(15378): at android.os.Handler.handleCallback(Handler.java:725)
01-09 15:54:49.026: E/AndroidRuntime(15378): at android.os.Handler.dispatchMessage(Handler.java:92)
01-09 15:54:49.026: E/AndroidRuntime(15378): at android.os.Looper.loop(Looper.java:153)
01-09 15:54:49.026: E/AndroidRuntime(15378): at android.app.ActivityThread.main(ActivityThread.java:5297)
01-09 15:54:49.026: E/AndroidRuntime(15378): at java.lang.reflect.Method.invokeNative(Native Method)
01-09 15:54:49.026: E/AndroidRuntime(15378): at java.lang.reflect.Method.invoke(Method.java:511)
01-09 15:54:49.026: E/AndroidRuntime(15378): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:833)
01-09 15:54:49.026: E/AndroidRuntime(15378): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:600)
01-09 15:54:49.026: E/AndroidRuntime(15378): at dalvik.system.NativeStart.main(Native Method)
Solution
If you're getting a NullPointerException
on this line:
copyDirectoryOneLocationToAnotherLocation(currentDir, currentDir);
That means that currentDir
is null. I don't see you assign it to anything in your code, so assign it to the Directory and then it will not be null anymore.
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