How to make for loops in Java increase by increments other than 1

Question

If you have a for loop like this   for j   0  j lt  90  j        It works fine  But when you have a for loop like this   for j   0  j lt  90  j 3      it doesn t work  Could someone please explain this to me

User · Answer

for  let i   0  i  lt   value  i  n       increments by n   code statement       this format works for me incrementing index by n  for  let i   0  i  lt   value  i  4       increments by 4   code statement       if n   4 this it will increment by 4

User · Answer

It s just a syntax error  You just have to replace j 3 by j j 3 or j  3

User · Answer

Simply try this  for int i 0  i lt 5  i i 2    value increased by 2   body     OR  for int i 0  i lt 5  i  2    value increased by 2   body

User · Answer

Change   for j   0  j lt  90  j 3    to   for j   0  j lt  90  j j 3

User · Answer

It should be like this  for int j   0  j lt  90  j    3     but watch out for   for int j   0  j lt  90  j    3     or   for int j   0  j lt  90  j   j   3

User · Answer

In your example  j  3 increments by 3    Not much else to say here  if it s syntax related I d suggest Googling first  but I m new here so I could be wrong

User · Answer

You can also write code as   for int i 0 i lt n i              statements        i i 2   cause you want to increment i by 3

User · Answer

That   s because j 3 doesn   t change the value of j  You need to replace that with j   j   3 or j    3 so that the value of j is increased by 3   for  j   0  j  lt   90  j    3

User · Answer

If you have a for loop like this   for j   0  j lt  90  j        In this loop you are using shorthand provided by java language which means a postfix operator use-then-change  which is equivalent to j j 1   so the changed value is initialized and used for next operation   for j   0  j lt  90  j 3      In this loop you are just increment your value by 3 but not initializing it back to j variable  so the value of j remains changed

User · Answer

for j   0  j lt  90  j   j 3         j 3 will not assign the new value to j  add j j 3 will assign the new value to j and the loop will move up by 3    j   is like saying j   j 1  so in that case your assigning the new value to j just like the one above

User · Answer

for j   0  j lt  90  j        j   means j j 1  j value already 0 now we are adding 1 so now the sum value of j 1 became 1  finally we are overriding the j value 0  with the sum value 1       so here we are overriding the j value by j 1  So each iteration j value will be incremented by 1   for j   0  j lt  90  j 3      Here j 3 means j value already 0 now we are adding 3 so now the sum value of j 3 became 3 but we are not overriding the existing j value  So that JVM asking the programmer  you are calculating the new value but where you are assigning that value to a variable i e j   That s why we are getting the compile-time error   invalid AssignmentOperator     If we want to increment j value by 3 then we can use any one of the following way    for  int j 0  j lt  90  j  3   -- gt  here each iteration j value will be incremented by 3   for  int j 0  j lt  90  j j 3  -- gt  here each iteration j value will be incremented by 3

User · Answer

Since nobody else has actually tackled Could someone please explain this to me  I believe I will   j   is shorthand  it s not an actual operation  ok it really IS  but bear with me for the explanation   j   is really equal to the operation j   j   1  except it s not a macro or something that does inline replacement  There are a lot of discussions on here about the operations of i     i and what that means  because it could be intepreted as i       i OR  i        i  Which brings us to  i   versus   i  They are called the post-increment and pre-increment operators  Can you guess why they are so named  The important part is how they re used in assignments  For instance  you could do  j i    or j   i  We shall now do an example experiment      declare them all with the same value  for clarity and debug flow purposes    int i   0  int j   0  int k   0      yes we could have already set the value to 5 before  but I chose not to  i   5   j   i    k     i   print i  j  k      pretend this command prints them out nicely    to the console screen or something  it s an example   What are the values of i  j  and k   I ll give you the answers and let you work it out     i   7  j   5  k   7  That s the power of the pre and post increment operators  and the hazards of using them wrong  But here s the alternate way of writing that same order of operations      declare them all with the same value  for clarity and debug flow purposes    int i   0  int j   0  int k   0      yes we could have already set the value to 5 before  but I chose not to  i   5   j   i  i   i   1    post-increment  i   i   1    pre-increment k   i   print i  j  k      pretend this command prints them out nicely    to the console screen or something  it s an example   Ok  now that I ve shown you how the    operator works  let s examine why it doesn t work for j 3     Remember how I called it a  shorthand  earlier  That s just it  see the second example  because that s effectively what the compiler does before using the command  it s more complicated than that  but that s not for first explanations   So you ll see that the  expanded shorthand  has i   AND i   1 which is all that your request has   This goes back to math  A function is defined where f x    mx   b or an equation y   mx   b so what do we call mx   b     it s certainly not a function or equation  At most it is an expression  Which is all j 3 is  an expression  An expression without assignment does us no good  but it does take up CPU time  assuming the compiler doesn t optimize it out      I hope that clarifies things for you and gives you some room to ask new questions  Cheers

User · Answer

The  increment  portion of a loop statement has to change the value of the index variable to have any effect  The longhand form of    j  is  j   j   1   So  as other answers have said  the correct form of your increment is  j   j   3   which doesn t have as terse a shorthand as incrementing by one   j   3   as you know by now  doesn t actually change j  it s an expression whose evaluation has no effect

[java] How to make for loops in Java increase by increments other than 1

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