I am wondering, how do I append an element to the end of an ArrayList in Java? Here is the code I have so far:
public class Stack {
private ArrayList<String> stringList = new ArrayList<String>();
RandomStringGenerator rsg = new RandomStringGenerator();
private void push(){
String random = rsg.randomStringGenerator();
ArrayList.add(random);
}
}
"randomStringGenerator" is a method which generates a random String.
I basically want to always append the random string at the end of the ArrayList, much like a stack (Hence the name "push").
Thank you so much for your time!
4 Answers
Here is the syntax, along with some other methods you might find useful:
//add to the end of the list
stringList.add(random);
//add to the beginning of the list
stringList.add(0, random);
//replace the element at index 4 with random
stringList.set(4, random);
//remove the element at index 5
stringList.remove(5);
//remove all elements from the list
stringList.clear();
I know this is an old question, but I wanted to make an answer of my own. here is another way to do this if you "really" want to add to the end of the list instead of using list.add(str) you can do it this way, but I don't recommend.
String[] items = new String[]{"Hello", "World"};
ArrayList<String> list = new ArrayList<>();
Collections.addAll(list, items);
int endOfList = list.size();
list.add(endOfList, "This goes end of list");
System.out.println(Collections.singletonList(list));
this is the 'Compact' way of adding the item to the end of list. here is a safer way to do this, with null checking and more.
String[] items = new String[]{"Hello", "World"};
ArrayList<String> list = new ArrayList<>();
Collections.addAll(list, items);
addEndOfList(list, "Safer way");
System.out.println(Collections.singletonList(list));
private static void addEndOfList(List<String> list, String item){
try{
list.add(getEndOfList(list), item);
} catch (IndexOutOfBoundsException e){
System.out.println(e.toString());
}
}
private static int getEndOfList(List<String> list){
if(list != null) {
return list.size();
}
return -1;
}
Heres another way to add items to the end of list, happy coding :)
I ran into a similar problem and just passed the end of the array to the ArrayList.add() index param like so:
public class Stack {
private ArrayList<String> stringList = new ArrayList<String>();
RandomStringGenerator rsg = new RandomStringGenerator();
private void push(){
String random = rsg.randomStringGenerator();
stringList.add(stringList.size(), random);
}
}
import java.util.*;
public class matrixcecil {
public static void main(String args[]){
List<Integer> k1=new ArrayList<Integer>(10);
k1.add(23);
k1.add(10);
k1.add(20);
k1.add(24);
int i=0;
while(k1.size()<10){
if(i==(k1.get(k1.size()-1))){
}
i=k1.get(k1.size()-1);
k1.add(30);
i++;
break;
}
System.out.println(k1);
}
}
I think this example will help you for better solution.
