Control statements
Conditional control statements in java
Conditional control or decision making is done in java with if statements and switch statement.
Simple if()
Ensures that a statement is executed only when a condition is true. Conditions typically involve comparison of variables or quantities for equality or inequality
Syntax :
if(condition)
{
statement;
}
statement;
Example:
if (age >= 18)
System. out.println(“You are eligible to vote.”);
if ... else()
This is two way branching statement and is an extension of if statement and informs what to do if the condition evaluates to false.
Syntax :
if(condition)
{
statement;
}
else
{
statement;
}
Example :
if(a>b)
System.out.println("A is big");
else
System.out.println("B is big");
Nested if()
When if ..else statement is placed inside another if..else statement then it is called nested if…else statement. This is used for making multiway decisions
Syntax :
if(condition)
{
if(condition)
{
statement;
}
else
{
statement;
}
}
else
{
statement;
}
Example:
if(a>b)
{
if (a>c)
System.out.println("A is big");
else
System.out.println("C is big");
}
else
{
if (b>c)
System.out.println("B is big");
else
System.out.println("C is big")
else ... if ladder
The <condition1> is evaluated first. If it evaluates to true, then /* statements 1 */ are executed. The rest of the if-else-if construct is ignored.
If <condition 1> is false, then <condition 2> is checked; if <condition 2> is false, <condition 3> is checked.
This process continues until a condition evaluates to true. At this point, the statements following the associated if or else-if are executed.
If none of the conditions evaluate to true, if there is a final else clause, those statements are executed. Otherwise, execution continues with the statements after the if-else-if construct.
If the clauses for any of the conditions is more than one statement, than curly brackets are necessary. Otherwise, the brackets are optional.
Syntax :
if(condition)
{
statement;
}
else if(condition)
{
statement;
}
else
{
statement;
}
statement;
Example:
if(avg>79)
System.out.println("Distinction");
else if(avg>59)
System.out.println("First Class");
else if(avg>39)
System.out.println("Second Class");
else
System.out.println("Fail");
Using switch
switch case is used to check a number of possible execution paths. A switch can work with the byte, short, char and int primitive data types.
Java has a built in multi-way design statement called switch
The expression inside the switch case may be an integer or a character.
Since JDK 1.7 we have facility to take an String inside the switch case.
Each case must be end with colon (:)
The default statement is executed if there is no match with any case specified in the switch case.
Each case must be terminated with a break; statement.
Syntax :
switch(expression)
{
case value1: statement();
break;
case value2: statement();
break;
case value3: statement();
break;
default: statement();
break;
}
Example:
switch (day)
{
case 1:
System.out.println("Monday");
break;
case 2:
System.out.println("Tuesday");
break;
case 3:
System.out.println("Wednesday");
break;
case 4:
System.out.println("Thrusday");
break;
case 5:
System.out.println("Friday");
break;
case 6:
System.out.println("Saturday");
break;
case 7:
System.out.println("Sunday");
break;
default:
System.out.println("Invalid entry");
}
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