🚀 Day 26 of My Automation Journey – Conditions, Inputs & Do-While Loop

Today’s session was a mix of core Java fundamentals + tricky logic + real-world usage 💡
We explored how conditions work, how loops behave without braces, user input handling, and even touched JSON/XML basics.

Let’s break it down step by step 👇

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🔹 1. Condition Must Be Boolean (True/False)

In Java, every condition must return either true or false.

❌ Invalid Example

int i = 1;
while(i) {   // ❌ Compilation Error
    System.out.println(i);
}

👉 Why error?

• Java does NOT allow non-boolean conditions
• Unlike C/C++, numbers are not treated as true/false

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✅ Correct Example

int i = 1;
while(i <= 5) {
    System.out.println(i);
    i++;
}

✔ Condition → i <= 5 → returns boolean
✔ Hence valid

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🔹 2. True / False Direct Conditions

You can directly use true or false in conditions.

✅ Example

if(true) {
    System.out.println("Always runs");
}

✔ Output:

Always runs

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❌ Example

if(false) {
    System.out.println("Never runs");
}

✔ Output:

(no output)

👉 This is useful for testing or debugging

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🔹 3. Removing Curly Braces { }

Java allows skipping { } if only one statement is present.

✅ Example

for(int i = 1; i <= 5; i++)
    System.out.println(i);

✔ Output:

1 2 3 4 5

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⚠️ Tricky Case

for(int i = 1; i <= 5; i++)
    System.out.println(i);
    System.out.println("Done");

✔ Output:

1 2 3 4 5
Done

👉 Only the first statement is inside loop
👉 Second statement runs once after loop

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🔹 4. Infinite Loop (By Default True)

If condition is always true → loop never stops 😱

Example

for(;;) {
    System.out.println("Infinite Loop");
}

👉 This is equivalent to:

while(true) {
    System.out.println("Infinite Loop");
}

✔ Used in:

• Servers
• Continuous monitoring systems

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🔹 5. break and continue

🔸 break → stops loop completely

for(int i = 1; i <= 5; i++) {
    if(i == 3)
        break;
    System.out.println(i);
}

✔ Output:

1
2

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🔸 continue → skips current iteration

for(int i = 1; i <= 5; i++) {
    if(i == 3)
        continue;
    System.out.println(i);
}

✔ Output:

1
2
4
5

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🔹 6. Taking Input from User (Scanner)

To read input in Java, we use Scanner.

Example

import java.util.*;

public class Test {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);

        System.out.print("Enter your name: ");
        String name = sc.nextLine();

        System.out.println("Hello " + name);
    }
}

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⚠️ Important Notes

❌ Java does NOT directly support char input
✔ Workaround:

char ch = sc.next().charAt(0);

✔ For String:

String name = sc.nextLine();

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🔹 7. Multiple Inputs Example

Scanner sc = new Scanner(System.in);

System.out.print("Enter Tamil mark: ");
int tamil = sc.nextInt();

System.out.print("Enter English mark: ");
int english = sc.nextInt();

int total = tamil + english;

System.out.println("Total mark: " + total);

✔ Output Example:

Enter Tamil mark: 80
Enter English mark: 90
Total mark: 170

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🔹 8. JSON vs XML (Basic Understanding)

🔸 JSON (JavaScript Object Notation)

{
  "username": "Manikandan",
  "password": "1234"
}

✔ Lightweight
✔ Easy to read
✔ Mostly used in APIs

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🔸 XML (Extensible Markup Language)

<user>
    <username>Manikandan</username>
    <password>1234</password>
</user>

✔ Structured format
✔ Used in older systems / configs

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🔹 9. Do-While Loop

👉 Runs at least once, even if condition is false

Example

int i = 1;

do {
    System.out.println(i);
    i++;
} while(i <= 5);

✔ Output:

1 2 3 4 5

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🔥 Key Difference

Loop Type	Condition Check
while	Before execution
do-while	After execution

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🧠 Key Takeaways

✔ Condition must always be boolean
✔ Java does NOT allow non-boolean conditions
✔ Without {}, only one statement is considered
✔ Infinite loops happen when condition is always true
✔ break → exits loop
✔ continue → skips iteration
✔ Scanner is used for user input
✔ JSON is lightweight, XML is structured
✔ do-while runs at least once

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🏁 Conclusion

Today was all about understanding how Java actually behaves under the hood 🧠

These small concepts are very important when:

• Writing automation scripts
• Handling test data
• Building logic-driven frameworks

🔥 Step by step, building strong fundamentals in automation!

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🤖 A Small Note
I used ChatGPT to help structure and refine this blog while keeping the concepts aligned with my learning.