I use the following method, but every time i use it i got error.
I cant figure out why because i perfrom this checking
if(unWanted == null || unWanted[0] == null)
The error is in this code:
unWanted[0] == null
but if i do only
if(unWanted == null)
It doest not see unWaned as null.
Thank for helping :)
the error code:
05-12 06:24:41.293: E/AndroidRuntime(24373): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.workoutlog/com.example.workoutlog.AddWorkOutPage}: java.lang.ArrayIndexOutOfBoundsException: length=0; index=0
My method:
public void checking(){
DataBaseMain data = new DataBaseMain(this);
data.open();
String[] unWanted = data.getAllUnwantedExercies();
data.close();
if(unWanted == null || unWanted[0] == null)
Toast.makeText(this, "good", Toast.LENGTH_LONG).show();
else
Toast.makeText(this, "bad", Toast.LENGTH_LONG).show();
The method to get the String array from my DB.
public String[] getAllUnwantedExercies() {
Cursor c = ourDatabase.query(true, TABLE_NAME, new String[] {COLUMN_NOT_ON_LIST_EXERCISE}, null, null, COLUMN_NOT_ON_LIST_EXERCISE, null, null, null);
int dayExercise = c.getColumnIndex(COLUMN_NOT_ON_LIST_EXERCISE);
if(c.getCount() < 1)
return null;
int f = 0;
for (c.moveToFirst(); !c.isAfterLast(); c.moveToNext()){
if(c.getString(dayExercise) != null && c.getString(dayExercise).equals("") == false)
f++;
}
String[] list = new String[f];
int j = 0;
for (c.moveToFirst(); !c.isAfterLast(); c.moveToNext()){
if(c.getString(dayExercise) != null && c.getString(dayExercise).equals("") == false){
list[j] = c.getString(dayExercise);
j++;
}
}
return list;
}
unWanted[0] == null
It's clear that your array has no values in it. Attempting to reference the first index of an array of length 0, as explained in your stack trace, is a run time error.
unWanted == null
This doesn't work because the array object itself is not null.
A work around
A simple solution here is, at the end of your function, check the length of the array. If it is 0, you know it has no values, and you can return null.
if(list.length == 0)
{
return null;
}
else
{
return list;
}
or more concisely:
return list.length == 0? null:list;
Then when you get your array back from your function, all you need to do is test to check if the array is null.
if(unWanted == null)
{
// Array is empty.
}
Maybe just change this line:
if(unWanted == null || unWanted[0] == null)
By this one:
if(unWanted.length <= 0)
unWanted[0] == null
Here you are trying to check the first position of your array is null or not. Instead of this check your array size is 0 or not.
if(unWanted.length==0){
// your code
}
I hope this will help you.
You need to check that the length is greater than 0. It is not null because you are returning a list albeit an empty list. So it isn't null but also doesn't have a length
unWanted is not null does not mean you can reference it is first element by using unWanter[0] because it might be an empty array.
Related
I do the following:
if (!items.containsKey(item) || items.get(item).getPrice() != 0) continue;
For the above I get the warning. In order to avoid it, I do
Objects.requireNonNull(items.get(item)).getPrice() != 0
The above works but it's not clean and anyway, I just checked that the item exists so for sure it's not null.
Is there a cleaner way? Thanks
Here is the full line of code:
if (!Utils.getInstance().items.containsKey(item.getId()) || Objects.requireNonNull(Utils.getInstance().items.get(item.getId())).getPrice() == 0) continue;
if (!Utils.getInstance().items.containsKey(item.getId()) || Objects.requireNonNull(Utils.getInstance().items.get(item.getId())).getPrice() == 0) continue;
That's quite a feat for a code!
You make to many logic in a single line.You need to divide it to a more readable one.
Let's simplify your code,
First, remove the requireNonNull. So it will be like this:
if (!Utils.getInstance().items.containsKey(item.getId()) || Utils.getInstance().items.get(item.getId()).getPrice() == 0) continue;
Second, extract Utils.getInstance().items to a single variable. So, it will be like this (Here I assume you're using a Map with HashMap):
// assuming a HashMap
HashMap items = Utils.getInstance().items;
if (!items.containsKey(item.getId()) || items.get(item.getId()).getPrice() == 0) continue;
Third, we extract the key as a single variable:
// assuming a HashMap
HashMap items = Utils.getInstance().items;
// assuming a string as the key
String key = item.getId();
if (!items.containsKey(key) || items.get(key).getPrice() == 0) continue;
Now, we can split the or part to this:
// assuming a HashMap
HashMap items = Utils.getInstance().items;
// assuming a string as the key
String key = item.getId();
if (!items.containsKey(key)) continue;
if(items.get(key).getPrice() == 0) continue;
the last code will gives you warning because Map.get() can return a null value. You can see from Map.get() documentation. So, we need to guard it.
Here the final version:
// assuming a HashMap
HashMap items = Utils.getInstance().items;
// assuming a string as the key
String key = item.getId();
if (!items.containsKey(key)) continue;
if(items.get(key) == null) continue;
if(items.get(key).getPrice() == 0) continue;
It maybe end up with more extra lines for your code. But it makes your code more readable and maintainable because you don't need to push your brain to hard to understand the code.
You could annotate your method/variable with #NonNull
#NonNull
fun test(){
}
#NonNull
private lateinit var test:List<String>
Maybe you should change your if condition from
if (!items.containsKey(item) || items.get(item).getPrice() != 0) continue;
to
if (items.get(item) == null || items.get(item).getPrice() != 0) continue;
You don't need to ensure that items contains the key item, just do it in following way:
Object value = items.get(item);
if (value == null || value.getPrice() != 0) continue;
I have an field in database that is null
When I retrieve it in a cursor it is null.
I can tell that from the
cursor.isNull(1) is true
So when I do cursor.getLong(1) it should throw an exception according to the documentation. but it actually retrieves 0 without and exception.
any ideas why?
If you take a look at the implementation of the method getLong() in MatrixCursor , you can see the following code:
#Override
public long getLong(int column) {
Object value = get(column);
if (value == null) return 0;
if (value instanceof Number) return ((Number) value).longValue();
return Long.parseLong(value.toString());
}
If the value is null, then 0 is returned.
I want to get value from several variables for example user1, user2, user3, user4.
how to check if variables are empty otherwise get the value and ignore variables that empty.
how I achieve this?, and sorry for newbie question...
if I do this
if(user1 != null && user2!= null && user3 != null && user4 != null){
user1.getText(); // or v1 = user1.value();
user2.getText(); // or v2 = user2.value();
user3.getText(); // or v3 = user3.value();
user4.getText(); // or v4 = user4.value();
}
which I dont want to do that, I just want to get the variable which had value in it and save it in array
Try with the following code.
ArrayList<String> listItems=new ArrayList<String>();
if(user1!=null)
{
listItems.add(user1.getText());
}
if(user2!=null)
{
listItems.add(user2.getText());
}
if(user3!=null)
{
listItems.add(user3.getText());
}
if(user4!=null)
{
listItems.add(user4.getText());
}
String [] arrayData = listItems.toArray(new String[listItems.size()]);
Note:You can also use isEmpty() method instead of checking for not a null value.
You mean a null check?
Value v1;
Value v2;
if (user1 != null) {
v1 = user1.value();
}
if (user2 != null) {
v2 = user2.value();
}
...etc
If you are dealing with String values then you may want to check the empty or null using TextUtils.isEmpty(str) API
public static boolean isEmpty (CharSequence str) Returns true if the string is null or 0-length.
if(user1!=null && !TextUtils.isEmpty(user1.getText()){
//not empty or null
}
I'm getting this error.
09-05 16:17:27.460: E/CursorWindow(29553): Failed to read row 0, column -1 from a CursorWindow which has 1 rows, 8 columns.
09-05 16:17:27.465: E/AndroidRuntime(29553): FATAL EXCEPTION: main
09-05 16:17:27.465: E/AndroidRuntime(29553): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.nesv.landstar/com.nesv.landstar.LandstarPage}: java.lang.IllegalStateException: Couldn't read row 0, col -1 from CursorWindow. Make sure the Cursor is initialized correctly before accessing data from it.
I don't know what I'm doing wrong with my code. Here it is:
Cursor c = null;
try
{
c = landstarDB.rawQuery("SELECT * FROM DriverShipment", null);
}catch (Exception e) {
Log.w("Error selecting table", "Error selecting table");
}
if (c != null && c.moveToFirst()) {
c.moveToFirst();
do {
Log.i("cctid:", c.getString(c.getColumnIndex("cctid")));
if(c.getString(c.getColumnIndex("cctid")) == cctid)
{
isRecorded = true;
shipmentId = c.getString(c.getColumnIndex("cctid"));
origin = c.getString(c.getColumnIndex("origin"));
destination = c.getString(c.getColumnIndex("destination"));
protectTime = c.getString(c.getColumnIndex("protect_time"));
readyTime = c.getString(c.getColumnIndex("ready_time"));
etat = c.getString(c.getColumnIndex("eta"));
if(c.getString(c.getColumnIndex("isAccepted")) == "1")
{
isAccepted = true;
}
}
}while(c.moveToNext());
}
c.close();
Any ideas? Thanks!
column -1 tells you that there is no column cctid, and getColumnIndex returns -1.
Also
c.getString(c.getColumnIndex("cctid")) == cctid
Will not work. Strings are compared using the equals method.
I suggest you post your table creation Query so we can see why the column is not there.
You have call c.moveToFirst(); two times
if (c != null && c.moveToFirst()) {
c.moveToFirst(); // Remove this one
Change your loop as below:
if (c.getCount > 0) {
c.moveToFirst();
do {
Log.i("cctid:", c.getString(c.getColumnIndex("cctid")));
if(c.getString(c.getColumnIndex("cctid")) == cctid)
{
isRecorded = true;
shipmentId = c.getString(c.getColumnIndex("cctid"));
origin = c.getString(c.getColumnIndex("origin"));
destination = c.getString(c.getColumnIndex("destination"));
protectTime = c.getString(c.getColumnIndex("protect_time"));
readyTime = c.getString(c.getColumnIndex("ready_time"));
etat = c.getString(c.getColumnIndex("eta"));
if(c.getString(c.getColumnIndex("isAccepted")) == "1")
{
isAccepted = true;
}
}
}while(c.moveToNext());
}
Can anyone tell me what is going wrong here. I am trying to obtain the address using reverse geocoding..`
if (locationGPS != null) {
list = geocoder.getFromLocation(locationGPS.getLatitude(),
locationGPS.getLongitude(), 3);
if (list != null) {
if (list.size() > 0) {
strZipcode = list.get(0).getPostalCode();
strAdminArea = list.get(0).getAdminArea();
strLocality = list.get(0).getLocality();
strAddressLine = list.get(0).getAddressLine(0);
Log.d(TAG, "list of address: "+ list);
Log.d(TAG, "Data: "+ mobileDataEnabled);
Log.d(TAG, "Data: "+ mobile);
int count = 0;
while ((strZipcode == null || strAdminArea == null
|| strLocality == null || (strAddressLine == null || strAddressLine == "USA"))
&& count < list.size()) {
strZipcode = list.get(count).getPostalCode();
strAdminArea = list.get(count).getAdminArea();
strLocality = list.get(count).getLocality();
strAddressLine = list.get(count)
.getAddressLine(count);
count++;
}`
This thing works fine and gives out the right address. But sometimes it gives out null for the all of the values which i am trying to retrieve despite the fact that i have a check in place for null values.. Am i missing something here?
Reverse Geocoder does not always return a value. It sounds weird but this is the way it is. F0r example if you hit for address 5 times, you won't be lucky enough to get response for all hits. You may get 3 instead. So workaround may be, instead of hitting geocoder one at a time, try looping your request to 2 or 3 times or more, one of the requests will work hopefully.