Problem: How to remove duplicate elements from the array
Solution:
Contents:
1: Create a file & Declare a Class
2: Declare the main method
3: Declare Variables
4: Taking inputs
5: Passing input to the second method
6: Declare the second method which contains our logic
7: actual logic for removing duplicates from an array
8: Returning a pure array
9: Display the Output
Note: I am following the java naming conventions in this solution.
It is not forced to follow, but it is a good habit as a programmer.
And it will make your program readable for other programmers.
1. Create a file & Declare a Class
Create a file EliminateDuplicatesFromArray.java
Open a file and declare class
import java.util.Scanner;
class EliminateDuplicatesFromArray{
}
According to java conventions, Filename and class name must be the same which makes it easier to maintain and organize your programs.
We are importing the Scanner class to take inputs
2 : Declare the main method
public static void main(String as[]){
}
This is the starter method of any java program
3 : Declare Variables in main method
Now declare necessary variables that will require in the program.
- Two Arrays one for input and another for output
int[] list,pureList;
- Size of Array
int len;
- object of Scanner class
Scanner s=new Scanner(System.in);
It will require if we use Dynamic Initialization
4 : Taking inputs
Two ways to take input/initializing array
- Static Initialization
list={10,20,30,30,30,30,40,50,10,40,10,50,10,0,0,0,10,70,80,10,90,10,90,90,90};
- Dynamic Initialization For this, we need to take input from the user. So we need an Object of Scanner class to get input as declared in step 3.
System.out.println("Enter Size of array");
int len=s.nextInt();
list=new int[len]; // instantiation
for(int i=0;i<list.length;i++)
{
System.out.print("Enter "+i+" element :=> ");
list[i]=s.nextInt(); // initialization
}
5 : Passing input to the second method
pureList=removeDuplicates(list);
passing list
as input to the method removeDuplicates
and it will return to pureList
.
6 : Declare the second method
Creating the second method
public static int[] eliminateDuplicates(int[] list){
}
why static
? because we're calling it from the main method.
7 : Actual logic for removing duplicates from an array
- Declare Variables in
eliminateDuplicates
method
int key,newSize;
int[] pureList;
the key
variable is for selecting each element of the list
as key
and comparing key
with each element of the list
pureList
is for storing pure Array
newSize
is the length of pureList
Array
7.1 : Initialize inputs
newSize=list.length;
the list variable will contain passed impure array
Currently, newSize
will contain length of input array(impure Array)
newSize
will be decreased as the element is removed.
7.2 : Process the Array [Actual Logic]
for(int i=0;i<newSize-1;i++)//for select each element as key
{
key=list[i];//store first element as Key
for(int j=i+1;j<newSize;j++){/* Start Comparing with Next Element
otherwise key element will be removed */
if(key==list[j])
{
newSize=newSize-1; /* Decreasing Length to Skip the Last
element which already shifted up
after below loop */
for(int k=j;k<newSize;k++)//Shift Up Array to remove Duplicate {
list[k]=list[k+1]; //remove duplicate
}
j--; //for skipped element after deletion
}
}
}
- 1st For loop
Selecting Each element of the array
Assigning to
Key
variable - 2nd For loop
Selecting Each element of the array after the
key
element - If Statement
Comparing key with each element of array excluding
key
If match found then decrementnewSize
variable because in 3rd loop we are deleting one element from the array - 3rd For loop removing an element from the array by shifting up the next element
Now decrement 2nd loop counter j
by one because after deletion of element next element's index will become deleted element's index.
So the next element will not be skipped for comparison.
8 : Returning a pure array
After this list
has no duplicates values but it contains dummy values
So Copy list with newSize
length to pureList
array.
pureList=new int[newSize]; //Instantiate pureList Array with newSize
for(int p=0;p<newSize;p++)
{
pureList[p]=list[p];
}
return pureList;
9 : Display the Output
for(int x: pureList)//for each loop for display output
{
System.out.println(x);
}
Source Code
And also, if you ever have any problems, questions or suggestions, please feel free to drop me a line or leave a comment below.
Thank you.
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