Develop Reference

Array of methods

I am trying to randomly call methods to make it use a different animation every time to display a textview. I trie using an array but not sure how to implement it. My array looks like this (obviously I know it shouldn't be strings but not sure what data type or if even possible this way).
String [] mAnimations = {"Hinge","RollIn", "Landing",
"BounceIn", "BounceInDown", "BounceInLeft", "BounceInRight",
"BounceInUp", "FadeIn", "FadeInUp", "FadeInDown", "FadeInLeft",
"FadeInRight","FlipInX", "RotateIn", "RotateInDownLeft", "RotateInDownRight",
"RotateInUpLeft", "RotateInUpRight", "SlideInLeft", "SlideInRight",
"SlideInUp", "SlideInDown", "ZoomIn", "ZoomInDown", "ZoomInLeft",
"ZoomInRight", "ZoomInUp"};
Putting any of the correct animations by themselves it works fine (Note BounceInLeft):
YoYo.with(Techniques.BounceInLeft)
.duration(1000)
.playOn(textView);
But what I am trying to do is randomly pick an animation from the array something like this:
Random rand = new Random();
int n = rand.nextInt(mAnimations.length) + 1;
YoYo.with(Techniques.(mAnimations[n]))
.duration(1000)
.playOn(textView);
Thanks for your help
Nicholas

Best Directly Assign method based on Random numbers.Because (mAnimations[n]) value consider as String.
String [] mAnimations = {"Hinge","RollIn", "Landing",
"BounceIn", "BounceInDown", "BounceInLeft", "BounceInRight",
"BounceInUp", "FadeIn", "FadeInUp", "FadeInDown", "FadeInLeft",
"FadeInRight","FlipInX", "RotateIn", "RotateInDownLeft", "RotateInDownRight",
"RotateInUpLeft", "RotateInUpRight", "SlideInLeft", "SlideInRight",
"SlideInUp", "SlideInDown", "ZoomIn", "ZoomInDown", "ZoomInLeft",
"ZoomInRight", "ZoomInUp"};
Random rand = new Random();
int n = rand.nextInt(mAnimations.length);
if(n==0)
{
YoYo.with(Techniques.Hinge).duration(1000).playOn(textView);
}
if(n==1)
{
YoYo.with(Techniques.RollIn).duration(1000).playOn(textView);
}

Search for number in array, Android

I'm searching for numbers in my app, but it does not work, where is the problem please ?!
numrat is int[] and fint is a number from fytyratint[]...
int fint = fytyratint[nrRendor];
int nse = Arrays.binarySearch(numrat, fint);
if (nse <0 ){
pS++;
tvS.setText("Sakt: "+ Integer.toString(pS));
}
else
{
pG++;
tvG.setText("Gabimet: " + Integer.toString(pG));
}
So nse must be negative if number does not exist in int[] numrat and must be positive if fint exists on int[] numrat..
This is what I read on internet..
but in my example it is always negative.. ??!!

If you want Arrays.binarySearch() to work you should sort your array like written here:
binarySearch() ...
Performs a binary search for value in the ascending sorted array
array. Searching in an unsorted array has an undefined result. It's
also undefined which element is found if there are multiple
occurrences of the same element.
You may do it like this:
Arrays.sort(numrat);
Arrays.binarySearch(numrat, fint);

Getting Int from EditText causes error?

So first of all sorry if this has already been asked and answered before, I couldn't find anything relating to my issue.
So I'm working on a project for college and I need to get int values from EditText widgets. I was told to use parseInt to do this however when running my program, that line of code causes the application to crash. I don't know what I'm doing wrong, I'm still very new to android development, thanks for the help :)
public void Calculate (View view)
{
int MilesTravelled;
int FuelUsed;
int MPG;
/* the two lines below are what cause the application to crash */
MilesTravelled = Integer.parseInt(txtMilesTravelled.getText().toString());
FuelUsed = Integer.parseInt(txtFuelUsed.getText().toString());
FuelUsed = (int) (FuelUsed / 4.55);
MPG = MilesTravelled / FuelUsed;
lblMPG.setText(FuelUsed);
}

Do you have this in the onCreate() function?
EditText txtMilesTravelled = (EditText) findViewById(R.id.YourEditText);
But I think you mixed Integer and int. They are not the same:
See this link!

First of all, don't capitalize the first letter of an variables or method names. Following the Java coding conventions, only do that for classes.
What is probably causing your app to crash is you trying to set the text of a label to an integer. The setText method for a TextView needs to take in a string.
So change:
lblMPG.setText(FuelUsed);
to:
lblMPG.setText(String.valueOf(FuelUsed));
Otherwise it might be that it's trying to parse a non-numerical string to an integer.
For exmaple, if the EditText is blank, it will cause your app to crash. To prevent that, try this:
int MilesTravelled = 0, FuelUsed = 0;
try {
MilesTravelled = Integer.parseInt(txtMilesTravelled.getText().toString());
FuelUsed = Integer.parseInt(txtFuelUsed.getText().toString());
} catch (NumberFormatException nfe) {
Toast.makeText(getApplicationContext(), "Error NFE!", 0).show();
nfe.printStackTrace();
}
This way, it will catch a NumberFormatException error (parsing a string to an integer that can't be represented as an integer, such as "hello"). If it catches the error, it will toast that an error has occurred and your integer variables will remain 0.
Or you could just test if the strings contain only digits using the following regex:
int MilesTravelled = 0, FuelUsed = 0;
if (txtMilesTravelled.getText().toString().matches("[0-9]+")) {
MilesTravelled = Integer.parseInt(txtMilesTravelled.getText().toString());
} else {
// contains characters that are not digits
}
if (txtFuelUsed.getText().toString().matches("[0-9]+")) {
FuelUsed = Integer.parseInt(txtFuelUsed.getText().toString());
} else {
// contains characters that are not digits
}
If that's not the problem, then make sure you define your variables properly.
txtMilesTravelled and txtFuelUsed should be EditText:
EditText txtMilesTravelled = (EditText)findViewById(R.id.txtMilesTravelled);
EditText txtFuelUsed = (EditText)findViewById(R.id.txtFuelUsed);
And make sure that your R.id.editText actually exists on your layout and that the IDs are the correct ones.
Last thing, make sure FuelUsed is not 0 before calculating MPG because then you are dividing by 0:
int MPG = 0;
if (FuelUsed != 0) {
MPG = MilesTravelled / FuelUsed;
}

I am assuming that you're entering perfect integers in the EditTexts. It might be a good idea to use the trim function txtMilesTravelled.getText().toString().trim() before using parseInt.
However, I think the major problem is here : lblMPG.setText(FuelUsed);
FuelUsed is an integral value, when you pass an integer to setText(), it looks for a string resource with that integral value. So you should be passing a String to the setText() method.
Use : lblMPG.setText(Integer.toString(FuelUsed));

Resources.GetIdentifier() returning 0 for layout (Android)

I'm attempting to get the int resource id for a layout resource by name, using Resources.GetIdentifier() of the Android API, but it returns 0. I'm using c#/monodroid/Xamarin, but regular java Android knowledge would apply too I suspect. Here's my code:
int resId = Resources.GetIdentifier(typeName, "layout", _activity.PackageName);
Where typeName = "FrmMain", and in my project I have the file "Resources/Layout/FrmMain.axml". Any ideas?

This is old, but for everyone getting this problem, I think it is because the resource name should be in lower case, so:
int resId = Resources.GetIdentifier("FrmMain", "layout", _activity.PackageName);
does not work, but:
int resId = Resources.GetIdentifier("frmmain", nameof(Resource.Layout).ToLower(), _activity.PackageName);
should work

I don't know why that's failing, but wouldn't something like Resource.Layout.FrmMain achieve what you're after?
edit:
According to this answer, you can (and should) use reflection to achieve what you're after, so I think you would try something like this:
var resourceId = (int)typeof(Resource.Layout).GetField(typeName).GetValue(null);
which does seem to work on my app and should get what you're after.

In my case, this issue came up when I had to upgrade the target SDK due to google's new policy since November, 2018.
I had to display some strings according to the server response code (ex : api_res_001_suc), but it did not work on the upgraded version.
The overall version, about 22 as I recall, had to be changed to 27.
The cause of the issue seems to be the default translation stuff. When I put all the default translation for every string, it worked.
My code is,
getResources().getIdentifier(resName, "string", "packageName");

I've created a ResourceHelper class to handle this situation. Here is the code:
public static class ResourceHelper
{
public static int FindId(string resourceId)
{
var type = typeof(Resource.Id);
var field = type.GetField(resourceId);
return (int)field.GetRawConstantValue();
}
public static int FindLayout(string layoutName)
{
var type = typeof(Resource.Layout);
var field = type.GetField(layoutName);
return (int)field.GetRawConstantValue();
}
public static int FindMenu(string menuName)
{
var type = typeof(Resource.Menu);
var field = type.GetField(menuName);
return (int)field.GetRawConstantValue();
}
}
Actually I'm improving it because I need to use it from another Assembly and it's restricted to work in the same Assembly of the Droid App. I'm thinking about put a generic method (or an Extension one) to do this. Here is a draft of my idea:
public static int FindResource<T>(string resourceName)
{
var type = typeof(T);
var field = type.GetField(resourceName);
return (int)field.GetRawConstantValue();
}
Hope it can help you.

Android: Set a random image using setImageResource

I need a help with setting a random image using setImageResource method.
In the drawable folder, I have a jpeg file named photo0.jpg, photo1.jpg...photo99.jpg.
And the following code works:
int p = R.drawable.photo1;
image.setImageResource(p);
The above will display photo1.jpg but I want to show a random image.
I tried the following but it doesn't work.
String a = "R.drawable.photo";
int n = (int) (Math.random()*100)
String b = Integer.toString(n);
String c = a+b;
int p = Integer.parseInt(c);//checkpoint
image.setImageResource(p);
It seems like the string "R.drawable.photoXX" isn't being changed to integer at the checkpoint.
Could someone please teach me a right code?
Thank you in advance.

Strings are pretty much evil when it comes to work like this due to the overhead costs. Since Android already provides you with integer id's I would recommend storing all of them to an int array and then using a random number for the index.
The code would look something like this:
int imageArr[] = new int[NUM_IMAGES];
imageArr[1] = R.drawable.photo;
//(load your array here with the resource ids)
int n = (int)Math.random()*NUM_IMAGES;
image.setImage(imageArr[n]);
Here we have a pretty straight forward implementation and bypass all the creation and destruction that occurs with the string concats.

maybe the error is here
int n = (int) (Math.random()*100)
put % not * Like this
int n = (int) (Math.random()%100)
to get all numbers under 100