无法将元素添加到ArrayList <Integer>

Question

So I am trying to create a ArrayList of Integers and then iterate variables into it. Only the first value that I specify is being added.

 private ArrayList<Integer> heights(String detail) {
        ArrayList<Integer> heights = new ArrayList<Integer>();
        heights.add(0);
        switch(detail) {
            case "L": for(Integer i = 100; i <= 1000; i=+50) { heights.add(i); } break;
            case "H": for(Integer i = 100; i <= 1000; i=+25) { heights.add(i); } break;
        }
        return heights;
    }

Value of heights("H"):

heights: [0]

Answer 1

The Problem is in for loop. Use int instead of Integer class....

The code below works properly...

import java.util.*;  
class Test{
        private ArrayList<Integer> heights(String detail) {
            ArrayList<Integer> heights = new ArrayList<Integer>();
            heights.add(0);
            switch(detail) {
                case "L": for(int i = 100; i <= 1000; i=i+50) { heights.add(i); } break;
                case "H": for(int i = 100; i <= 1000; i=i+25) { heights.add(i); } break;
            }
            return heights;
        }
     public static void main(String args[]){
            Test t = new Test();
            System.out.println(t.heights("H"));
         }
    }