Control Statements in Java

 

🧭 Control Statements in Java / నియంత్రణ వాక్యాలు (Control Statements)

🔹 Definition / నిర్వచనం:

Control statements are used to control the flow of execution of a program based on certain conditions or loops.

Javaలో Control Statements అనేవి program execution (program ఎక్కడి నుండి ఎక్కడికి వెళ్ళాలో) నిర్ణయిస్తాయి.

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⚙️ Types of Control Statements / నియంత్రణ వాక్యాల రకాలు

Java has three main types of control statements:

Type	Telugu Meaning	Used For
1. Decision Making Statements	నిర్ణయాత్మక వాక్యాలు	Conditions check చేయడానికి
2. Looping Statements	పునరావృత వాక్యాలు	Code repeatedly execute చేయడానికి
3. Jump Statements	దూకు వాక్యాలు	Control ను ఒక place నుండి మరో place కు మార్చడానికి

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🧩 1. Decision-Making Statements

These statements help Java decide which block of code to execute.

✅ (a) if Statement

Syntax:

if (condition) {
    // code executes only if condition is true
}

Example:

int age = 20;
if (age >= 18) {
    System.out.println("Eligible to vote");
}

🗣️ Output: Eligible to vote

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✅ (b) if-else Statement

Syntax:

if (condition) {
   // true block
} else {
   // false block
}

Example:

int marks = 40;
if (marks >= 35) {
    System.out.println("Pass");
} else {
    System.out.println("Fail");
}

🗣️ Output: Pass

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✅ (c) if-else-if Ladder

Used when there are multiple conditions.

int marks = 75;
if (marks >= 90) {
    System.out.println("Grade A");
} else if (marks >= 75) {
    System.out.println("Grade B");
} else {
    System.out.println("Grade C");
}

🗣️ Output: Grade B

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✅ (d) Nested if Statement

An if inside another if.

int age = 20;
int weight = 60;

if (age >= 18) {
   if (weight >= 50) {
       System.out.println("Eligible for donation");
   }
}

🗣️ Output: Eligible for donation

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✅ (e) switch Statement

Used when you have many possible values for one variable.

int day = 3;
switch(day) {
    case 1: System.out.println("Monday"); break;
    case 2: System.out.println("Tuesday"); break;
    case 3: System.out.println("Wednesday"); break;
    default: System.out.println("Invalid day");
}

🗣️ Output: Wednesday

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🔁 2. Looping Statements (Iteration Statements)

Used to execute code multiple times.

Type	Description
for loop	When number of iterations known
while loop	When number of iterations not known
do-while loop	Executes at least once

(a) for loop

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

🗣️ Output:
1
2
3
4
5

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(b) while loop

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

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(c) do-while loop

Executes at least once, even if condition is false.

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

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🚀 3. Jump Statements

Used to transfer control from one part to another.

Statement	Function
break	Terminates loop or switch
continue	Skips current iteration
return	Exits from method

(a) break Example:

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

🗣️ Output:
1
2

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(b) continue Example:

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

🗣️ Output:
1
2
4
5

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(c) return Example:

public static void main(String[] args) {
   System.out.println("Before return");
   return;
   // Code after return won't execute
}

🗣️ Output: Before return

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🎯 Summary Table

Type	Statements	Use
Decision Making	if, if-else, if-else-if, nested if, switch	Based on conditions
Looping	for, while, do-while	Repeat code
Jump	break, continue, return	Change control flow