﻿ Java - Display the pattern like a diamond

# Java: Display the pattern like a diamond

## Java Conditional Statement: Exercise-21 with Solution

Write a Java program to display the pattern like a diamond.

Test Data
Input number of rows (half of the diamond) :7

Pictorial Presentation:

Sample Solution:

Java Code:

``````import java.util.Scanner;
public class Exercise21 {

public static void main(String[] args)

{
int i,j,r;
System.out.print("Input number of rows (half of the diamond) : ");
Scanner in = new Scanner(System.in);
r = in.nextInt();
for(i=0;i<=r;i++)
{
for(j=1;j<=r-i;j++)
System.out.print(" ");
for(j=1;j<=2*i-1;j++)
System.out.print("*");
System.out.print("\n");
}

for(i=r-1;i>=1;i--)
{
for(j=1;j<=r-i;j++)
System.out.print(" ");
for(j=1;j<=2*i-1;j++)
System.out.print("*");
System.out.print("\n");
}

}
}
```
```

Sample Output:

```Input number of rows (half of the diamond) : 7
*
***
*****
*******
*********
***********
*************
***********
*********
*******
*****
***
*

```

Flowchart:

Java Code Editor:

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﻿

## Java: Tips of the Day

IsPowerOfTwo

Checks if a value is positive power of two.

To understand how it works let's assume we made a call IsPowerOfTwo(4).

As value is greater than 0, so right side of the && operator will be evaluated.

The result of (~value + 1) is equal to value itself. ~100 + 001 => 011 + 001 => 100. This is equal to value.

The result of (value & value) is value. 100 & 100 => 100.

This will value the expression to true as value is equal to value.

```public static boolean isPowerOfTwo(final int value) {
return value > 0 && ((value & (~value + 1)) == value);
}
```

Ref: https://bit.ly/3sA5d4I

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