how do i print the element "e" in arraylist "list" out?
ArrayList<Dog> list = new ArrayList<Dog>();
Dog e = new Dog();
list.add(e);
System.out.println(list);
This question is related to
java
Do you want to print the entire list or you want to iterate through each element of the list? Either way to print anything meaningful your Dog class need to override the toString() method (as mentioned in other answers) from the Object class to return a valid result.
public class Print {
public static void main(final String[] args) {
List<Dog> list = new ArrayList<Dog>();
Dog e = new Dog("Tommy");
list.add(e);
list.add(new Dog("tiger"));
System.out.println(list);
for(Dog d:list) {
System.out.println(d);
// prints [Tommy, tiger]
}
}
private static class Dog {
private final String name;
public Dog(final String name) {
this.name = name;
}
@Override
public String toString() {
return name;
}
}
}
The output of this code is:
[Tommy, tiger]
Tommy
tiger
First make sure that Dog class implements the method public String toString() then use
System.out.println(list.get(index))
where index is the position inside the list. Of course since you provide your implementation you can decide how dog prints itself.
You should override toString() method in your Dog class. which will be called when you use this object in sysout.
Your code requires that the Dog class has overridden the toString() method so that it knows how to print itself out. Otherwise, your code looks correct.
If you want to print an arraylist with integer numbers, as an example you can use below code.
class Test{
public static void main(String[] args){
ArrayList<Integer> arraylist = new ArrayList<Integer>();
for(int i=0; i<=10; i++){
arraylist .add(i);
}
for (Integer n : arraylist ){
System.out.println(n);
}
}
}
The output is above code:
0
1
2
3
4
5
6
7
8
9
10
Printing a specific element is
list.get(INDEX)
I think the best way to print the whole list in one go and this will also avoid putting a loop
Arrays.toString(list.toArray())
Here is an updated solution for Java8, using lambdas and streams:
System.out.println(list.stream()
.map(Object::toString)
.collect(Collectors.joining("\n")));
Or, without joining the list into one large string:
list.stream().forEach(System.out::println);
Source: Stackoverflow.com