For example i want to make 10 Random object in java, but this code doesn't work, because an object name can't be an integer.
for(int i = 0; i < 10; i++)
{
Random i = new Random();
}
Any ideas?
4 Answers
You could build them into a List:
List<Random> randoms = new ArrayList<>();
for (int i = 0; i < 10; i++) {
randoms.add(new Random());
}
or an Array:
Random[] randoms = new Random[10];
for (int i = 0; i < randoms.length; i++) {
randoms[i] = new Random();
}
There are other options but these are the most common.
Comments
Use
for(int j = 0; j < 10; j++)
{
Random i = new Random();
}
instead should work.
But if it's me I'd like to use Stream.generate(Random::new).limit(10).
4 Comments
mustaccio
I don't think this will result in 10 usable
Random instances.
ice1000
@mustaccio He just want to create objects... I just helped him to make his code compile.
papaya
I think to be honest, try using a HaspMap() to create your object in a for loop.
RandomMap.put(i, new Random(i)); This will help you get back, your objects in this way > RandomMap.get(i);ice1000
If it's me I'd like to
Stream.generate(Random::new).limit(10)This is easy method
List<SomeClass> someClass = new ArrayList<>();
for (int i = 0; i < 100; i++) {
someClass.add(new SomeClass());
}
Comments
When you have written this code.
for(int i = 0; i < 10; i++)
{
Random i = new Random();
}
You were thinking that multiple object of Random class will be created by the name 0,1,2,3,4.......9 but it does not work that way.
If you would have use something like this:-
for(int i = 0; i < 10; i++)
{
Random "obj"+i = new Random();
}
Then also it will not work.
If you have ever work with String class then you know that in order to create multiple object of String you need to do something like this.
String s1,s2,s3;
// and then
s1="first String ";
s2="second String";
s3="third String";//and so on
Similar think can be done with Random:-
Random r1,r2,r3;
r1=new Random();
r2=new Random();
r3=new Random();
But if you want to create many of them Array come into role.(Although there are other options also).
You can create array of any thing int,float ,String and objects of any class.
here is the syntax:-
<Classname> <variableName>[]=new <ClassName>[No of objects to be created];
Now For Random class you can do something like this.
Random ranList[]=new Random[10];
By writing this line you have just created a array of Random but not yet instantiated the object using new Keyword.
for that you have to do something like this.
for(int i = 0; i < 10; i++)
{
Random ranList[i] = new Random();
}
now you have 10 object of Random type each store at a different index of ranList variable.
Hope it helped you!
2 Comments
Gergő Gutyina
Thank you for helping me, the array will do it. My other problem is I don't know how many object I need. Maybe 1, maybe 100. So if i create a Random rands[] = new Random[100] then every random will be loaded and using the RAM or no?
bit-shashank
@GergőGutyina Yes that is the problem with array,you need to know the size before hand but in your case you can use ArrayList class .
ias two different things. Use a different variable name.