Control Statements in Java - A Comprehensive Guide

When you run a program in Java, it smoothly executes from beginning to end. However, certain statements in Java allow you to change this order to suit your needs. You can control the flow of the execution. These statements are very essential to ensure that a program runs effectively and optimally.

In this article, we are going to learn about different types of statements that allow us to control the flow. It’s use cases with examples so that you will be familiar with the implementation of the control statement

Table of contents

• • Control Statements in Java
  • Decision-Making Statements in Java
    • • If statement
      • If-Else Statement
      • If Else-If statement
      • Switch Statement
  • Looping Control Statements in Java
    • • For loop
      • While loop
      • Do-while loop
  • Unconditional Control Statements/Jump Statements in Java
    • • break Statement
      • continue Statement
  • Conclusion

Control Statements in Java

Control Statements in Java are used to control the execution flow of the program. Let’s say you want to print 9 for a number of times and you don’t want to write print statement that number of times. What will you do? To solve this type of problem control statements are used in java.

Different situations may demand different execution flow of the program. There can be many different conditions which you want your program to follow.
Some of these situations can be:

• • • You want your program to execute the same statement number of times.
    • You want your program after executing a certain number of times

There are three types of control statements:

• • • 1. Decision-making statements in Java
      2. Looping Control Statements in Java
      3. Unconditional Control Statements/Jump Statements in Java

Decision-Making or Conditional Control Statements allows the program to select between the alternatives during the program execution.
They are also called as decision-making statements or selection statements.

if(condition){
// statements (if Block)
}
//other statements
• Below flow chart shows the condition of if block execution.

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2. If-Else Statement

If the condition is true then, it will execute the If block. Otherwise, it will execute the Else block.

if(condition){
// statements (if Block)
}
else{
// statements (Else block)
}
//other statements
• Below flow chart shows the condition of if block execution.

Execution flow chart of If-Else Statement

If the condition is true, then it will execute the If block. Otherwise, it will execute the Else-If block. Again, if the condition is not met, then it will move to the else block.

if(condition){
// statements (if Block)
}
else if{
// statements (Else-If block)
}
else{
//statements(Else Block)
}//other statements

Execution flow chart of If Else-If Statement

Program to understand If statements

class WriteExample{
public static void main(String []args){
int a=2; int b=3; int c=4;
if(a>b){
System.out.print(“Institute1”);
}
else if(a>c){
System.out.print(“Institute2”);
}
else{
System.out.print(“Intellipaat”);
}
}
}

Output:
Intellipaat

Switch statement allows program to select one action among multiple actions during the program execution.
Syntax:

Switch(variable/value/expression){
Case :
// statements [];
Case :
// statements [];
…
default:
// statements [];
}

• • • Based on the argument in the switch statement suitable case value will be selected and executed.
    • If no matching case found, then the default will be executed.
    • It is optional to write a break statement at the end of each case statement.

Program to understand switch statement:

class WriteExample{
public static void main(String []args){
int choice=2; int a=1;
switch(choice){
case a:
System.out.print(“For Right Study”); break;
case choice:
System.out.print(“Intellipaat Trainings”); break;
default:
System.out.print(“No choice found”); break;
}
} }
}

Output: Intellipaat Trainings

These are used to execute a block of statements multiple times. It means it executes the same code multiple times so it saves code. These are also called Iteration statements.

There are three types of looping control statements:

• • 1. For loop
    2. While loop
    3. Do-while loop

• • • It executes the code until condition is false.
    • It is used when number of iterations are known.

Syntax:

for(initialization; condition; increment/decrement){
//statements (For Body)
}

Program to understand for loop

class WriteExample{
public static void main(String []args){
int a=1;
for(int i=0; i<2; i++){
System.out.println(“Value of a is:”+ a); // string concatenation
a++; // increases value by 1
}
}
}

Output: Value of a is:1
Value of a is:2

2. While loop

• • • While loop executes till the condition becomes false.

Syntax:

while(condition){
// statements
}

Program to understand while loop

class Intellipaat {public static void main(String args[]) {
int i = 2;
while( i <=2 ) {
System.out.println("Intellipaat” );
i++;
}
}
}

Output:  Intellipaat

• • • When you are using for or while, then it will execute the loop body only if the condition if true.
    • In do-while loop, it will execute the loop first, then it checks the condition. So, it will execute the loop atleast once.
    • It is called exit controlled loop while for & while loop are called entry controlled loop.

Syntax:

do{
// statements
}while(condition);

Program to understand do-while loop

class Intellipaat {public static void main(String args[]){
int a = 2;
do{
System.out.println("Intellipaat”);
i++;
}while( a< =2 );
}
}

Output: Intellipaat

• • • break is a keyword. It is used within any control statements. It is used to terminate the execution of the current loop or switch statements.
    • Syntax: break; or break <label>;

class Intellipaat{ // break without label
public static void main(String args[]){
for(int i=1;i<=4;i++){
if(i==3) break;
System.out.println(“Intellipaat.com”);}
} }

Output:
Intellipaat.com
Intellipaat.com

/* break with label is used to terminate the number of loops below the label */
class Intellipaat{
public static void main(String args[]){
Termi:
for(int i=1;i<=4;i++){
for(int k=1;i<=4;k++){
if(i==3) break Termi;
System.out.println(“Intellipaat.com”);
}
}
} }

Output:
Intellipaat.com
Intellipaat.com

• • • continue is a keyword. It is used to continue the execution of the current loop with the next iteration.
    • Syntax: continue; or continue<label>;

class Intellipaat{ //continue without label
public static void main(String args[]){
for(int i=1;i<=4;i++){
System.out.print(“ “+i+” “);
if(i==3) continue;
System.out.println(“Intellipaat.com”);}
} }

Output:
1 Intellipaat.com
2 Intellipaat.com
3 4 Intellipaat.com

/* continue with label is used to continue the number of loops below the label */
class Intellipaat{
public static void main(String args[]){
Termi:
for(int i=1;i<=4;i++){
for(int k=1;i<=4;k++){
System.out.print(“ ”+i+” ”);
if(i==3) continue Termi;
System.out.println(“Intellipaat.com”);
}
}
} }

Output:
1 Intellipaat.com
2 Intellipaat.com
3 1 Intellipaat.com
2 Intellipaat.com
3 1 Intellipaat.com
This statement will keep on printing the same output till the memory gets full.

Conclusion

Every Java programmer should understand control statements and know how they influence the execution of a program. A developer is able to build powerful programs by using efficient, concise, and maintainable code with the help of conditional statements, loops, and jump statements. Such programs also perform better and are structured more effectively.