I'm storing a full method in a String (actually reading it from a file as a String). Now I need to execute the method which is in the String. I mean, in the MainActivity I have to execute this method inside the String. Is there any possible way to do it?
Thanks in Advance.
The method which is stored in the String is:
public void showTheText()
{
System.out.println("Hi There...");
}
Before doing this, if you are trying to execute code dynamically, keep in mind that guys on Google Play might not like it, as it can be use for remote execution of code, or code that wasn't analyzed by them.
That being said, in java there is no proper way of evaluating expressions in strings. But you can always embed some interpreter and make it execute the code (i.e. https://code.google.com/p/android-scripting/wiki/FAQ).
If your methods are present on some class of your application, you would only need the name of the method you want to execute and then use reflection to invoke it.
Related
So, what I'd like to achieve is:
I have a custom class which is basically a HttpRequest, I create the object with url, parameters, etc. And then I have to call execute() to execute it.
I was wondering, is there a way - by annotations, or whatever - to make Android Studio remind me to call this method?
I remember the was something similar with the android Toast, in the IDE a message like 'Did you forget to call show?' was shown if, in fact, I forgot to call show() after creating the Toast.
Thanks much to anyone who will help :)
You could try to create
Create a custom IntelliJ inspection
A custom LINT rule, if you want to check it on your build server and not on your local machine.
I have a andoid.graphics.path already created with moveto(),lineTo(),cubeto() and close().
How do I get back all these operations ?
I mean something like the following pseodcode:
operations[] = getOperations(mypath);
String sOperation=operation[0].type; // moveto,cubeto,lineto,close
int X=operation[0].x;
int Y=operation[0].y;
I'm afraid this isn't possible. In the source of android.graphics.Path, you'll observe that the method directly invokes the native method, and doesn't provide any mechanism of retrieving the segments.
If you wish to keep the tuples, I'd suggest maintaining your own array.
I need help with using an if statement in java, here is my code :
if(ans==1)
{
txtans.setText("This is a Prime Number");
}
else
{
txtans.setText("This is NOT a Prime Number");
}
if I remove the setText methods in both statements my program works, but when I leave them there and the program finds ans, then it quits, I'm wondering whats wrong with the statements? or is it not possible to use the setText method within if statements..if so how do I overcome this? What I want to do is print a string to the TextView layout when the ans = 1, any suggestions?
Yes, you can run txtans.setText() in an if statement just as well as you could run it if it wasn't in an if statement. You likely just don't have txtans initialised properly.
A quick google search brought up this as a way to print text to a textview.
Check your code, this erros usually comes when use findViewById() method in a wrong view.
In the activity you use like this findViewById(), maybe you need to call yourView.findViewById();
(If you post your class we can help you with more detailed answear.)
Also note that it is not allowed to call methods from Views from another Thread which created them. But a LogCat output including the Error will enlight us for shure :)
txtans might be NULL and you are trying to access a member of a NULL object.
i found this problem some time ago, but i solve it using this: getString(), or this: getResources().getString()
but now, for this case, it doesn't works, i think it's because i need to get the string values on a NON ANDROID ACTIVITY CLASS. I need the resource values on a remote connection class, that doesn't extends any kind of activity or service.
how i can acces to the variables from my strings.xml on this normal class?
this is the code where i get the error (it gets an integer, and not the string value)
String a =R.string.totalpermission;
Take a look at these two answers (are the same XD):
How to obtain AssetManager without reference to Context?
How can I get a resource content from a static context?
Just an advice: try to read some basic concepts... it seems you don't understand what the R class is and how to use it. Trust me, you waste less time studying than trying to figure out how things work.
I'll add something to existing answers since I found it very useful.
To get your strings you have to use a Context. Your activity will work just great.
String string = getString(R.string.myString);
But if you have something more complex... for exemple
R.string.result -> "You %1$s %2$d cats"
String result = getString(R.string.result, killed ? "killed": "saved", count);
That would give you a result like that:
You saved 10 cats or You killed 2 cats... and so on. You can pass parameters and positional arguments in strings will get replaced by your arguments in getString.
All Android resources are referenced via a resource ID, like R.string.totalpermission. You can see those numbers in R.java (although there's no reason to ever do that).
In cases of strings, you can easily get those using Context.getString. Bonus: You can even pass optional arguments and add dynamic strings that way. You always have a context - how are you getting called? If you really don't have a context, you can create one for the package your resources are in.
hi i have found Uri as immutable reference i dont know what it is the exact meaning of immutable reference... can anyone help me?
It's a variable that cannot be changed once set. Very useful when you have multithreaded code since being able to change a variable's value might be a source of many hard to find problems in your code.
If it's immutable, it's usually good.
A good example of an immutable class within the .NET Framework is System.String. Once you create a String object, you can’t ever change it. There’s no way around it; that’s the way the class is designed. You can create copies, and those copies can be modified forms of the original, but you simply cannot change the original instance for as long as it lives, without resorting to unsafe code. If you understand that, you’re probably starting to get the gist of where I’m going here: For a referencebased object to be passed into a method, such that the client can be guaranteed that it won’t change during the method call, it must itself be immutable.
In a world such as the CLR where objects are held by reference by default, this notion of immutability becomes very important. Let’s suppose that System.String was mutable, and let’s suppose you could write a method such as the following fictitious method:
public void PrintString( string theString )
{
// Assuming following line does not create a new
// instance of String but modifies theString
theString += ": there, I printed it!";
Console.WriteLine( theString );
}
Imagine the callers’ dismay when they get further along in the code that called this method and now their string has this extra stuff appended onto the end of it. That’s what could happen if System. String were mutable. You can see that String’s immutability exists for a reason, and maybe you should consider adding the same capability to your design.
EX: string is immutable...
if u have for ex string s =" whatever" and u output it with uppercase letter..for ex
Console.Write(s.ToUpper())the console will print u WHATEVER...but the string s will still be whatever... unlike the mutable type which will change the string from whatever to WHATEVER
"immutable" means "can't change the value"
"mutable" == "changeable"
"immutable" == "not changeable"
In java , every thing is treated as String and object , Now try to think that if have created a program of 10000 lines and in this there you have added "public" 100 times so do you think that every time this public is created in storage . else what we can do , we can created something like that when ever we find something like this we will fetch it from there there ( String pool )