Sum all the elements java arraylist

Question

If I had  ArrayList lt Double gt  m   new ArrayList lt Double gt     with the double values   inside  how should I do to add up all the ArrayList elements   public double incassoMargherita      double sum   0   for int i   0  i  lt  m size    i                     return sum      as

User · Accepted Answer

Two ways   Use indexes   double sum   0  for int i   0  i  lt  m size    i        sum    m get i   return sum    Use the  for each  style   double sum   0  for Double d   m      sum    d  return sum

User · Answer

Java 8  version for Integer  Long  Double and Float      List lt Integer gt  ints   Arrays asList 1  2  3  4  5       List lt Long gt  longs   Arrays asList 1L  2L  3L  4L  5L       List lt Double gt  doubles   Arrays asList 1 2d  2 3d  3 0d  4 0d  5 0d       List lt Float gt  floats   Arrays asList 1 3f  2 2f  3 0f  4 0f  5 0f        long intSum   ints stream                mapToLong Integer  longValue               sum         long longSum   longs stream                mapToLong Long  longValue               sum         double doublesSum   doubles stream                mapToDouble Double  doubleValue               sum         double floatsSum   floats stream                mapToDouble Float  doubleValue               sum         System out println String format               Integers   s  Longs   s  Doubles   s  Floats   s               intSum  longSum  doublesSum  floatsSum         15  15  15 5  15 5

User · Answer

Not very hard  just use m get i  to get the value from the list   public double incassoMargherita         double sum   0      for int i   0  i  lt  m size    i                  sum    m get i             return sum

User · Answer

I haven t tested it but it should work       public double incassoMargherita         double sum   0      for int i   0  i  lt  m size    i                  sum   sum   m get i             return sum

User · Answer

Using Java 8 streams   double sum   m stream        mapToDouble a - gt  a       sum     System out println sum

[java] Sum all the elements java arraylist

Examples related to java

Examples related to arraylist

Examples related to sum