is there Any Way To Make my Method Take many input variable but with out overloading ... could be my question not clear ... I mean Like That :
if I Have This Method
public void setValues (int val1,int val2 ,String val3){
}
what I want is : use this method with many way
setValues (val1,val2)
OR
setValues (val3)
why I want to do that with out overloading : Because if i have as example 10 variable i want to add many method with overloading but i don't like that ...
is there any way helps me to check variable or skip it in the same method ..
Thanks for help .
You can use varargs future to partially solve your problem http://docs.oracle.com/javase/1.5.0/docs/guide/language/varargs.html
This can be done if you have parameters of a same type.
But it will require that you will pass variables with the same type as a last param. It is not completely what you want, but it is a small workaround.
No there's no way to do that in Java without method overloading. One alternative would be to group those parameters which are related and make them fields of a class. Then the method would take an instance of that class as a parameter, and which ever parameters were optional would then be null.
Related
Here you can see that I can't pass that string parameter
I somehow learned how to pass a method in the same class but, when I want to call it from another class, I can't pass the arguments.
Several issues here:
the introduceMyself method accepts a higher-order function, but in its usage it seems that you don't want the method itself, but its result. I'd suggest replacing the getName parameter with name parameter and convert it to a regular string which will be provided externally by an invocation of said method.
In line 6, you have a syntax error. Since you're using an instance - person, you can replace the :: with a . like so: person.myNameIs("michael"). It's not working because :: passes the method itself, which you don't really want. Again, your code implies that you need to pass the result of the method and not the method itself.
Finally, you can pass higher order functions, but you can't pass them "with an argument". You can do one of 3 things:
Invoke the HOF locally and pass the result of the invocation
Pass the HOF and the argument and invoke them wherever it is you need to.
Pass the HOF and let the target pass whatever argument it chooses.
I am learning how to use the coroutines in kotlin. looking at some examples in the internet i found that within the context f the also operator the reference
it
is used. i could not find any explanation about the meaning of
it
please provide some brief explanantion about what does "it" mean
when you use the also method, it has 1 parameter.
Think of it in Java kinda like this:
foo.also(int it) {
// do stuff
}
In Kotlin, the it parameter is implicit (sometimes you might want to use it sometimes you don't).
If you want to rename it to something more readable you can
foo.also { newName ->
// do stuff with newName
}
Or just use it like it is
foo.also {
// do stuff with $it
}
So therefore when you are using a method (or a closure/lambda) if it has 1 parameter, then the implicit name of that parameter is always it.
Basically it represents the lambda parameter
let's say you want to perform anything on the variable but do to check the nullity first, you can do it like
var str:String?=null // str is of string type
now you can use it fail safe
str?.let{it:String// youll see like this
// now you can access str as **it**
}
it is the implicit name of a single parameter
For more information about it and this in scoping functions like also
In this question there is one line,
findViewById(R.id.go_to_play_store).setOnClickListener(this::goToPlayStore);
how does this line is exactly handling the click listener ?
Java8 introduces concept of Method references and Functional interfaces. If function onClickListener requires a function with one argument(a.k.a Functional Interface) then if return types and argument types match your function(which is goToPlayStore) then you can pass its reference as functional interface.
This is the new JAVA 8 language feature Lambda Expressions.
:: refer to a new syntax in Java 8 known as method references. You can reference a class or instance and pass along the method that will handle the event
On click its calling function called goToPlayStore () located in that activity or fragment.
its Method references in Java 8
Which allows us to refer to an existing method by name. Method references can be used in place of lambda expressions as long as they satisfy the requirements of the functional interface.
For static methods the syntax is
Classname::methodName
I'm using TTS in my app. I want to run a method when I ask for it. I created a Hashtable where I want to store my methods like:
table.put("qqq", say("www"));
I'm comparing my data with keys - it works, but it does not trigger a method.
This probably isn't possible with Hashtable, so please tell me how to do what I want in the simplest way
You should save the Object which calls that method:
Hashtable<String, MyObject> objects = new Hashtable<String, MyObject>();
objects.put("qqq",new MyObject());
MyObject test = objects.get("qqq");
test.say("www");
Check out java.lang.reflect, might be the right thing to use in your situation.
With reflection you can do something like this:
Method method = myObject.getClass().getMethod("say", String.class);
method.invoke(myObject, "www");
So all you would need to do is store the object, method name, and parameters and then you can dynamically invoke the method.
probably it is more a design issue.
Solution could be: if You are using only say() method, then store just a parameter that You would pass to the say() method (E.g., table.put("qqq", "www");). And when You need particular phrase to be found just call say(table.get("qqq"));.
Which parameter passing method is used in Android? Pass by reference or Pass by Value? Please provide an Android Specific example for the same.
All parameter passing in Java is by value.
Here is a nice article with all the details.
just like a normal Java Application:
Objects are passed by reference,
primitives are passed by value