20 Java Pattern Programs with Source Code: Explanation, Logic & Benefits (2026 Guide)

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Java pattern programs are some of the most commonly asked questions in coding interviews, competitive programming, and software development placements. Whether you are a beginner or an advanced learner, practicing these Java pattern programs helps you master loops, nested conditions, logic building, syntax clarity, and algorithmic thinking.

This complete guide on 20 Java Pattern Programs with Source Code includes:

  • Simple to advanced pattern examples
  • Output displayed cleanly
  • Complete Java source code
  • Logic explanation for each pattern
  • Benefits of learning pattern programs
  • Why they matter for jobs and interviews

Let’s dive in!

⭐ 1. Introduction to Java Pattern Programs

Java pattern programs refer to printing shapes, symbols, numbers, and alphabet arrangements using loops. These patterns improve your problem-solving approach and help you understand how nested loops work in Java.

You will see patterns like:

  • Star patterns
  • Number patterns
  • Alphabet patterns
  • Pyramid patterns
  • Square and rectangle patterns
  • Floyd’s triangle
  • Pascal’s triangle

These 20 Java pattern programs will help you become placement-ready.

⭐ 2. Benefits of Learning Java Pattern Programs

Before exploring the codes, it’s important to understand why Java pattern programs matter.

✔ 1. Boosts Logical Thinking

Pattern problems help improve logic building, especially in controlling loops.

✔ 2. Strengthens Loop Concepts

Patterns require nested loops and conditional logic.

✔ 3. Improves Debugging Skills

Pattern output helps you visualize errors quickly.

✔ 4. Helps in Coding Interviews

Almost all companies—TCS, Wipro, Infosys, HCL, Accenture—ask pattern programs.

✔ 5. Enhances Problem-Solving

Great for competitive programming and algorithmic thinking.

✔ 6. Improves Time & Space Analysis

You understand the complexity each pattern requires.

✔ 7. Prepares Beginners for Larger Programs

Pattern logic forms the foundation for data structures and algorithms.

⭐ 3. 20 Java Pattern Programs with Source Code

Below are the top 20 Java pattern programs with explanations.

Pattern 1: Square Star Pattern

Output

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

Code

for(int i = 1; i <= 4; i++) {
    for(int j = 1; j <= 4; j++) {
        System.out.print("*");
    }
    System.out.println();
}

Explanation

Two nested loops: outer loop for rows, inner loop for columns.

Pattern 2: Right Triangle Pattern

Output

*
**
***
****

Code

for(int i=1; i<=4; i++){
    for(int j=1; j<=i; j++){
        System.out.print("*");
    }
    System.out.println();
}

Logic

Prints stars equal to row number.

Pattern 3: Inverted Right Triangle

Output

****
***
**
*

Code

for(int i=4; i>=1; i--){
    for(int j=1; j<=i; j++){
        System.out.print("*");
    }
    System.out.println();
}

Pattern 4: Pyramid Star Pattern

Output

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

Code

int n = 4;
for(int i=1; i<=n; i++){
    for(int j=1; j<=n-i; j++) System.out.print(" ");
    for(int k=1; k<=(2*i-1); k++) System.out.print("*");
    System.out.println();
}

Pattern 5: Inverted Pyramid Pattern

Output

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

Code

int n = 4;
for(int i=n; i>=1; i--){
    for(int j=1; j<=n-i; j++) System.out.print(" ");
    for(int k=1; k<=(2*i-1); k++) System.out.print("*");
    System.out.println();
}

Pattern 6: Diamond Pattern

Output

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

Code

int n = 4;
// Upper
for(int i=1;i<=n;i++){
    for(int j=1;j<=n-i;j++) System.out.print(" ");
    for(int k=1;k<=2*i-1;k++) System.out.print("*");
    System.out.println();
}
// Lower
for(int i=n-1;i>=1;i--){
    for(int j=1;j<=n-i;j++) System.out.print(" ");
    for(int k=1;k<=2*i-1;k++) System.out.print("*");
    System.out.println();
}

Pattern 7: Number Triangle

Output

1
12
123
1234

Code

for(int i=1; i<=4; i++){
    for(int j=1; j<=i; j++){
        System.out.print(j);
    }
    System.out.println();
}

Pattern 8: Inverted Number Triangle

Output

1234
123
12
1

Code

for(int i=4;i>=1;i--){
    for(int j=1;j<=i;j++){
        System.out.print(j);
    }
    System.out.println();
}

Pattern 9: Repeating Number Triangle

Output

1
22
333
4444

Code

for(int i=1;i<=4;i++){
    for(int j=1;j<=i;j++){
        System.out.print(i);
    }
    System.out.println();
}

Pattern 10: Floyd’s Triangle

Output

1
2 3
4 5 6
7 8 9 10

Code

int num = 1;
for(int i=1;i<=4;i++){
    for(int j=1;j<=i;j++){
        System.out.print(num++ + " ");
    }
    System.out.println();
}

Pattern 11: Pascal’s Triangle

Code

int rows = 5;
for (int i = 0; i < rows; i++) {
    int number = 1;
    for (int k = 0; k < rows - i; k++)
        System.out.print(" ");
    for (int j = 0; j <= i; j++) {
        System.out.print(number + " ");
        number = number * (i - j) / (j + 1);
    }
    System.out.println();
}

Pattern 12: Alphabet Pattern (A Triangle)

Output

A
AB
ABC
ABCD

Code

for(int i=1;i<=4;i++){
    for(char ch='A'; ch<'A'+i; ch++){
        System.out.print(ch);
    }
    System.out.println();
}

Pattern 13: Hollow Square Pattern

Output

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

Code

int n=4;
for(int i=1;i<=n;i++){
    for(int j=1;j<=n;j++){
        if(i==1 || i==n || j==1 || j==n)
            System.out.print("*");
        else
            System.out.print(" ");
    }
    System.out.println();
}

Pattern 14: Hollow Triangle Pattern

Output

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

Code

int n=5;
for(int i=1;i<=n;i++){
    for(int j=1;j<=i;j++){
        if(j==1 || j==i || i==n)
            System.out.print("*");
        else
            System.out.print(" ");
    }
    System.out.println();
}

Pattern 15: Butterfly Pattern

Output

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

Code

int n=3;
for(int i=1;i<=n;i++){
    for(int j=1;j<=i;j++){
        System.out.print("*");
    }
    for(int j=1;j<=2*(n-i);j++){
        System.out.print(" ");
    }
    for(int j=1;j<=i;j++){
        System.out.print("*");
    }
    System.out.println();
}

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

Pattern 16: Hollow Pyramid

Output

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

Code

int n=4;
for(int i=1;i<=n;i++){
    for(int j=1;j<=n-i;j++) System.out.print(" ");
    for(int k=1;k<=2*i-1;k++){
        if(k==1 || k==2*i-1 || i==n)
            System.out.print("*");
        else
            System.out.print(" ");
    }
    System.out.println();
}

Pattern 17: Reverse Pyramid Numbers

Output

12321
 121
  1

Pattern 18: Zero-One Pattern

Output

1
01
101
0101

Code

for(int i=1;i<=4;i++){
    for(int j=1;j<=i;j++){
        if((i+j)%2==0) System.out.print("1");
        else System.out.print("0");
    }
    System.out.println();
}

Pattern 19: Cross Pattern

Output

*   *
 * *
  *
 * *
*   *

Code

int n=5;
for(int i=1;i<=n;i++){
    for(int j=1;j<=n;j++){
        if(j==i || j==n-i+1)
            System.out.print("*");
        else
            System.out.print(" ");
    }
    System.out.println();
}

Pattern 20: Number Pyramid

Output

   1
  121
 12321
1234321

Code

int n=4;
for(int i=1;i<=n;i++){
    for(int j=1;j<=n-i;j++) System.out.print(" ");
    for(int k=1;k<=i;k++) System.out.print(k);
    for(int k=i-1;k>=1;k--) System.out.print(k);
    System.out.println();
}

⭐ 4. Final Thoughts: Why These 20 Java Pattern Programs Matter

Learning these 20 Java pattern programs with source code will make you:

  • A better logical thinker
  • Confident in loops and conditions
  • Ready for coding interviews
  • Prepared for competitive exams
  • Stronger in debugging skills
  • Capable of writing cleaner and structured programs

Pattern programming is not just about printing stars—it’s about shaping your logic. The better your pattern-solving skills, the better your foundations in Java programming.

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