Printing *s as triangles in Java?

Question

My assignment in my Java course is to make 3 triangles. One left aligned, one right aligned, and one centered. I have to make a menu for what type of triangle and then input

Answer 1

This will print stars in triangle:

`   
public class printstar{
public static void main (String args[]){
int m = 0;
for(int i=1;i<=4;i++){
for(int j=1;j<=4-i;j++){
System.out.print("");}

for (int n=0;n<=i+m;n++){
if (n%2==0){
System.out.print("*");}
else {System.out.print(" ");}
}
m = m+1;
System.out.println("");
}
}
}'

Reading and understanding this should help you with designing the logic next time..

Answer 2

public class triangle {
    public static void main ( String arg[] ){

        System.out.print("Enter Triangle Size : ");
        int num=0;
        try{
            num=Integer.parseInt( read.readLine() );
        } catch(Exception Number){
            System.out.println("Invalid Number!");
        }
            for(int i=1;i<=num;i++){
                for(int j=1;j<num-(i-1);j++){
                    System.out.print(" ");
                }
                for(int k=1;k<=i;k++){
                    System.out.print("*");
                    for(int k1=1;k1<k;k1+=k){

                        System.out.print("*");
                    }
                }
                System.out.println();
            }
    }
}

Answer 3

// This is for normal triangle

for (int i = 0; i < 5; i++)
        {
            for (int j = 5; j > i; j--)
            {
                System.out.print(" ");
            }
            for (int k = 1; k <= i + 1; k++) {
                System.out.print(" *");
            }
            System.out.print("\n");
        }

// This is for left triangle, just removed space before printing *

for (int i = 0; i < 5; i++)
        {
            for (int j = 5; j > i; j--)
            {
                System.out.print(" ");
            }
            for (int k = 1; k <= i + 1; k++) {
                System.out.print("*");
            }
            System.out.print("\n");
        }

Answer 4

Find the following , it will help you to print the complete triangle.

package com.raju.arrays;

public class CompleteTriange {

public static void main(String[] args) {
    int nuberOfRows = 10;
      for(int row = 0; row<nuberOfRows;row++){

          for(int leftspace =0;leftspace<(nuberOfRows-row);leftspace++){
              System.out.print(" ");
          }
          for(int star = 0;star<2*row+1;star++){
              System.out.print("*");
          }
          for(int rightSpace =0;rightSpace<(nuberOfRows-row);rightSpace++){
              System.out.print(" ");
          }
          System.out.println("");
      }

}

}

          *          
     ***         
    *****        
   *******       
  *********      
 ***********     
*************    

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---

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Answer 5

You might be interested in this too

      Scanner sc = new Scanner(System.in);
      int n=sc.nextInt();
      int b=0;
      for(int i=n;i>=1;i--){
      if(i!=n){
      for(int k=1;k<=b;k++){
      System.out.print(" ");
        }
            }
       for(int j=i;j>=1;j--){
       System.out.print("*");
       if(i!=1){
       System.out.print(" ");
        }
            }
       System.out.println();
       b=b+2;
        }

Output:: 5

       * * * * * 
         * * * * 
           * * * 
             * * 
               *

Answer 6

Ilmari Karonen has good advice, and I'd just like to generalize it a bit. In general, before you ask "how can I get a computer to do this?" ask "how would I do this?"

So, if someone gave you an empty Word document and asked you to create the triangles, how would you go about doing it? Whatever solution you come up with, it's usually not hard to translate it to Java (or any other programming language). It might not be the best solution, but (hopefully!) it'll work, and it may point you to a better solution.

So for instance, maybe you would say that you'd type out the base, then go up a line, then type the next highest line, etc. That suggests that you can do the same in Java -- create a list of Strings, base-to-top, and then reverse them. That might suggest that you can just create them in reverse order, and then not have to reverse them. And then that might suggest that you don't need the list anymore, since you'll just be creating and printing them out in the same order -- at which point you've come up with essentially Ilmari Karonen's advice.

Or, maybe you'd come up with another way of doing it -- maybe you'd come up with Ilmari Karonen's idea more directly. Regardless, it should help you solve this and many other problems.