I want to add Integer to an Type safe ArrayList Of Float type.
Float a = new Float(1.1);
ArrayList<Float> obj = new ArrayList<Float>();
obj.add(a);//In the obj object I want to add integer. how can I do that?
Integer b = new Integer(1);
obj.add(b);/*The method add(Float) in the type ArrayList<Float>
is not applicable for the arguments (Integer)*/
Change the type of ArrayList to: ArrayList<Number>.
Because Number is the base class of Floatand Integer. So you can store both in the list.
or convert your Integer to a Float value obj.add(Float.valueOf(b));
valueOf forms “should generally be used in preference to the constructor[s as these methods are] likely to yield significantly better space and time performance by caching frequently requested values.” I just think it is better to not give misleading examples to beginners even though it arguably doesn't matter in the context of this question.
Integer to a Floatyou can not specify the type of the ArrayList like :
Float a = new Float(1.1);
ArrayList<Float> obj = new ArrayList<Float>();
obj.add(a);//In the obj object i want to add integer how can i do that
Integer b = new Integer(1);
ArrayList newobj = (ArrayList) obj;
newobj.add(b);
for (Object object : newobj) {
System.out.println(object.getClass());
}
Would output:
class java.lang.Float
class java.lang.Integer
Or you can Use an ArrayList<Number>:
Float a = new Float(1.1);
ArrayList<Number> obj = new ArrayList<Number>();
obj.add(a);//In the obj object i want to add integer how can i do that
Integer b = new Integer(1);
obj.add(b);
for (Number object : obj) {
System.out.println(object.getClass());
}
Would output:
class java.lang.Float
class java.lang.Integer
Try this
obj.add((float) b);
This get the float number of the integer
Or
obj.add(Float.parseInt(b));
What about
obj.add(b.floatValue());
Or use an ArrayList<Number>.
This is how i finally added Integer without changing ArrayList Type, But warnings are generated
public class MyArrayList{
public static void main(String[] args) {
Float a = new Float(1.1);
ArrayList<Float> obj = new ArrayList<Float>();
obj.add(a);
function1(obj);
for (Object obj2 : obj) {
System.out.println(obj2);
}
}
private static void function1(ArrayList list) {
Integer b = new Integer(1);
list.add(b);
}
}
Floatcan only, logically, contain Floats. Luckily both integers and floats are numbers so it's not too hard to convert an integer to a float.