﻿ Java exercises: Sort an array of positive integers of a given array in the specified pattern - w3resource # Java Array Exercises: Sort an array of positive integers of a given array in the specified pattern

## Java Array: Exercise-50 with Solution

Write a Java program to sort an array of positive integers of a given array, in the sorted array the value of the first element should be maximum, second value should be minimum value, third should be second maximum, fourth second be second minimum and so on.

Sample Pattern:

```[100, 10, 90, 20, 80, 30, 70, 40, 60, 50]
```

Sample Solution:

Java Code:

``````import java.util.Arrays;

public class Main
{
static int[] rearrange(int[] new_arra, int n)
{
int temp[] = new int[n];

int small_num = 0, large_num = n-1;
boolean flag = true;

for (int i=0; i < n; i++)
{
if (flag)
temp[i] = new_arra[large_num--];
else
temp[i] = new_arra[small_num++];

flag = !flag;
}

return temp;
}

public static void main(String[] args)
{
int nums[] = new int[]{10, 20, 30, 40, 50, 60, 70, 80, 90, 100};
int result[];

System.out.println("Original Array ");
System.out.println(Arrays.toString(nums));

result = rearrange(nums,nums.length);

System.out.println("New Array ");
System.out.println(Arrays.toString(result));

}
}
```
```

Sample Output:

```
Original Array
[10, 20, 30, 40, 50, 60, 70, 80, 90, 100]
New Array
[100, 10, 90, 20, 80, 30, 70, 40, 60, 50]
```

Flowchart: Visualize Java code execution (Python Tutor):

Java Code Editor:

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## Java: Tips of the Day

Array vs ArrayLists:

The main difference between these two is that an Array is of fixed size so once you have created an Array you cannot change it but the ArrayList is not of fixed size. You can create instances of ArrayLists without specifying its size. So if you create such instances of an ArrayList without specifying its size Java will create an instance of an ArrayList of default size.

Once an ArrayList is full it re-sizes itself. In fact, an ArrayList is internally supported by an array. So when an ArrayList is resized it will slow down its performance a bit as the contents of the old Array must be copied to a new Array.

At the same time, it's compulsory to specify the size of an Array directly or indirectly while creating it. And also Arrays can store both primitives and objects while ArrayLists only can store objects.

Ref: https://bit.ly/3o8L2KH