Creating a triangle with for loops

Question

I don t seem to be able to find the answer to this-   I need to draw a simple triangle using for loops                                                    I can make a half triangle  but I don t know how to add to my current loop to form a full triangle                                  for  int i 0  i lt 6  i          for  int j 0  j lt i  j          System out print             System out println            Thanks-

User · Answer

Try this   class piramid        public static void main String   args                   System out println  Hello World          int max   7       int k max 2      int j        printf   n        printf   n        printf   n        printf   n        for i k i gt 0 i--              for j 0 j lt k 1 j                      if i  j                           printf                         else if j gt i                         printf                             printf                        else                         printf                                                    printf   n                      hope it will help you

User · Answer

This will answer to your question  uncomment the commented code to display only outer line     public class TrianglePattern        public static void main String   args               This logic will generate the triangle for given dimension         int dim   10          for  int i   0  i  lt  dim  i                  for  int k   i  k  lt  dim  k                      System out print                                 for  int j   0  j  lt   i  j                        if  i    dim - 1                      if  j    0    j    i                          System out print                           else                         System out print                         else                     System out print                       System out print                                 System out println

User · Answer

First think of a solution without code  The idea is to print an odd number of    increasing by line  Then center the   by using spaces  Knowing the max number of   in the last line  will give you the initial number of spaces to center the first    Now write it in code

User · Answer

private static void printStar int x        int i  j      for  int y   0  y  lt  x  y         number of row of              for  i   y  i  lt  x - 1  i                   number of space each row             System out print                for  j   0  j  lt  y   2   1  j                   number of     each row             System out print                System out println

User · Answer

Homework question  Well you can modify your original  right triangle  code to generate an inverted  right triangle  with spaces So that ll be like for i 0  i lt 6  i          for j 6  j gt   6-i   j--                print  quot   quot              for x 0  x lt    2 i  1   x                  print  quot   quot              print  quot  n quot

User · Answer

for  int i 0  i lt 6  i             for  int k 0  k lt 6-i  k                   System out print                   for  int j 0  j lt i 2 1  j                   System out print                   System out println

User · Answer

Try this one in Java  for  int i   6  k   0  i  gt  0  amp  amp  k  lt  6  i--  k          for  int j   0  j  lt  i  j              System out print                 for  int j   0  j  lt  k  j              System out print                 for  int j   1  j  lt  k  j              System out print                 System out println

User · Answer

First of all  you need to make sure you re producing the correct number of   symbols  We need to produce 1  3  5 et cetera instead of 1  2  3  This can be fixed by modifying the counter variables   for  int i 1  i lt 10  i    2        for  int j 0  j lt i  j                  System out print                 System out println          As you can see  this causes i to start at 1 and increase by 2 at each step as long is it is smaller than 10  i e   1  3  5  7  9   This gives us the correct number of   symbols  We then need to fix the indentation level per line  This can be done as follows   for  int i 1  i lt 10  i    2        for  int k 0  k  lt   4 - i   2   k                  System out print                 for  int j 0  j lt i  j                  System out print                 System out println          Before printing the   symbols we print some spaces and the number of spaces varies depending on the line that we are on  That is what the for loop with the k variable is for  We can see that k iterates over the values 4  3  2  1 and 0 when    is 1 3  5  7 and 9  This is what we want because the higher in the triangle we are  the more spaces we need to place  The further we get down the triangle  we less spaces we need and the last line of the triangle does not even need spaces at all

User · Answer

I appreciate the OP is new to Java  so methods might be considered  advanced   however I think it s worth using this problem to show how you can attack a problem by breaking it into pieces   Let s think about writing a method to print a single line  telling the method which number line it is   public void printTriangleLine int rowNumber           we have to work out what to put here     We have to print some number of spaces  then some number of stars   Looking at the example  I can see that  if the first row is 0  it s  5-rowNumber  spaces and  2 rowNumber   1  stars   Let s invent a method that prints the rows of characters for us  and use it   public void printTriangleLine int rowNumber        printSequence      5 - rowNumber       printSequence      2   rowNumber   1       System out println         That won t compile until we actually write printSequence    so let s do that   public void printSequence String s  int repeats        for int i 0  i lt repeats  i              System out print s             Now you can test printSequence on its own  and you can test printTriangleLine on its own  For now you can just try it out by calling those methods directly in main    public static void main String    args        printSequence  a  3       System out println        printTriangleLine 2           run it and verify  with your eyes  that it outputs   aaa            When you get further into programming  you ll want to use a unit testing framework like jUnit  Instead of printing  you d more likely write things like printTriangleLine to return a String  which you d print from higher up in your program   and you would automate your testing with commands like   assertEquals             TriangleDrawer triangleLine 2    assertEquals           TriangleDrawer triangleLine 0     Now we have the pieces we need to draw a triangle   public void drawTriangle         for int i 0  i lt 5  i              printTriangleLine i             The code we have written is a bit longer than the answers other people have given  But we have been able to test each step  and we have methods that we can use again in other problems  In real life  we have to find the right balance between breaking a problem into too many methods  or too few  I tend to prefer lots of really short methods   For extra credit    adapt this so that instead of printing to System out  the methods return a String -- so in your main   you can use System out print drawTriangle    adapt this so that you can ask drawTriangle   for different sizes -- that is  you can call drawTriangle 3  or drawTriangle 5  make it work for bigger triangles  Hint  you will need to add a new  width  parameter to printTriangleLine

User · Answer

Well  there will be two sequences size-n for spaces and  2  n 1   -1 for stars  Here you go   public static void main String   args        String template                                      int size    template length   2       for int n 0 n lt size n             System out print template substring 0 size-n  replace                    System out println template substring 0   2  n 1   -1

User · Answer

This lets you have a little more control and an easier time making it   public static int biggestoddnum   31   public static void main String   args        for  int i 1  i lt biggestoddnum  i    2                for  int k 0  k  lt    biggestoddnum   2  - i   2   k                          System out print                         for  int j 0  j lt i  j                          System out print                         System out println                Just change public static int biggestoddnum s value to whatever odd number you want it to be  and the for int k     has been tested to work

User · Answer

A fun  simple solution   for  int i   0  i  lt  5  i       System out println                 substring i  5   2 i

[java] Creating a triangle with for loops

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