JAVA PROGRAM • LEVEL 17 — DATA STRUCTURES & ALGORITHMS IN JAVA
Implement Merge Sort in Java
Learn implement merge sort in java with a complete, compiler-ready Java 17 example.
PROBLEM UNDERSTANDING
Input and expected output
No input required
[1, 3, 5, 8, 9]
COMPLETE JAVA 17 PROGRAM
Complete Java 17 implementation
import java.util.*;class Main{static void sort(int[] a,int l,int r){if(l>=r)return;int m=(l+r)/2;sort(a,l,m);sort(a,m+1,r);int[] temp=new int[r-l+1];int i=l,j=m+1,k=0;while(i<=m&&j<=r)temp[k++]=a[i]<=a[j]?a[i++]:a[j++];while(i<=m)temp[k++]=a[i++];while(j<=r)temp[k++]=a[j++];System.arraycopy(temp,0,a,l,temp.length);}public static void main(String[] args){int[] a={8,3,5,1,9};sort(a,0,a.length-1);System.out.println(Arrays.toString(a));}}CURRENT STEP
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SELECTED LINE
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EXPECTED OUTPUT FOR THE SAMPLE
[1, 3, 5, 8, 9]
PROGRAM EXPLANATION
Algorithm and explanation
- Initialize the deterministic sample values used for implement merge sort in java.
- Apply Merge sort and Divide and conquer in the order shown by the program.
- Print the final result and compare it with the documented sample output.
This Java 17 example demonstrates Merge sort and Divide and conquer through a complete, executable program. The values are intentionally small so students can trace each statement, verify the output, and then modify the example safely in the online compiler.
EFFICIENCY
Time and space complexity
O(n log n)
O(n)
DEBUGGING CHECKLIST
Common mistakes
Keep the class name Main and the entry method signature public static void main(String[] args) when using the online compiler.
Check the loop boundary and update expression carefully to avoid skipping the final value or creating an infinite loop.
Java is case-sensitive, and every statement that requires a semicolon must end with one.