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Control statements
Control statements are of three types They are
1.Conditional / decision for selection statement
2. Looping / iterative / repetitive statement they are also called as pre and post conditional checking statement
3. Jumping statement
1. Conditional statements (if, if else, else if, nested if)
if syntax: if(condition)
{ True block statement;
}
Statement x;
Example:
import java.util.Scanner;
//checking number +,-,0
public class ifDemo{
public static void main(String[] args) {
Scanner sc= new Scanner(System.in);
System.out.println("Enter a value ");
int n=sc.nextInt();
if(n>0)
System.out.println("Positive number!!!");
if (n<0)
System.out.println("Negative number");
if(n==0)
System.out.println("Given number is zero");
System.out.println("Demo on if statement");
sc.close();
}}
2.If else syntax:
if(condition)
{ True block statement
}
else
{ False block statement
}
Statement x;
Example
Write a program to check given number is even or odd.
import java.util.Scanner;
public class ifelseDemo {
public static void main(String[] args) {
Scanner sc= new Scanner(System.in);
System.out.println("Enter any number ");
int n=sc.nextInt();
if(n%2==0)
System.out.println("Even number");
else
System.out.println("Odd number");
System.out.println("Demo on if else");
sc.close();
}}
3. Else if
Else if ladder is ment for checking more than one condition
Syntax: if(condition)
{ Statement 1;
}
else if(condition 2)
{ Statement 2;
}
else if(Condition 3)
{ Statement 3;
}
else
Statement n;
Example
import java.util.Scanner;
public class check_number {
public static void main(String[] args) {
double a,b;
Scanner sc= new Scanner(System.in);
System.out.println("Enter a value");
a=sc.nextDouble();
System.out.println("Enter b value");
b=sc.nextDouble();
if(a>b)
System.out.println("a is greater then b");
else if(b>a)
System.out.println("b is greater than a ");
else
System.out.println("a is equal to b");
sc.close();
}}
4. Nested if
• If statement present in another if is called nested if.
Syntax:
if(condition 1){
if(condition 2)
{ Statement 1;
}
else {
Statement 2;
}
}
else {
Statement 3;
}
Example
Write a program to check whether a person is eligible to donate blood or not where age >18 and weight > 60.
import java.util.*;
class blooddonation
{ public static void main (String args[])
{ int age,wt;
System.out.println("Enter your age and weight");
Scanner sc=new Scanner (System.in);
age=sc.nextInt();
wt=sc.nextInt();
if(age>18){
if(wt>60)
System.out.println("Eligible for bood donation");
else{
int wtgain=60-wt;
System.out.println("Please gain"+wtgain+"kg");
}
}
else{
int agegain=18-age;
System.out.println("Please wait for"+agegain"+"year");
}
System.out.println("Demo on nested if);
} } }
4. Switch
Switch is also a multi condition checking statement
Syntax:
switch(option)
{ case label 1:
Statement 1; break;
}
{ case label 2:
Statement 2; break;
}
default: statement ; break;
Rules
• option cannot be a float value
• case label cannot be repeated
• case label can be an expression
• default is optional
• no statement can be placed between case label
Example 1
import java.util.*;
class switchdemo{
public static void main (String args[]){
int n;
Scanner sc=new Scanner (System.in);
System.out.println("enter a value between 0 and 4");
n=sc.nextInt();
switch(n){
case 1: System.out.println("one"); break;
case 2: System.out.println("two"); break;
case 3: System.out.println("three"); break;
default: System.out.println("out of range");
break;
}}}
2. Write a program to perform basic calculator for performing arithmetic operations on supplied two integers.
import java.util.*;
class calculator{
public static void main (String args[]){
int a,b;
Scanner sc=new Scanner (System.in);
System.out.println("enter 2 values");
a=sc.nextInt();
b=sc.nextInt();
System.out.println("enter any operator");
String ch=sc.next();
switch(ch){
case "+": System.out.println(a+b); break;
case "-": System.out.println(a-b); break;
case "*": System.out.println(a*b); break;
case "/": System.out.println(a/b); break;
case"%": System.out.println(a%b);break;
}}}
3. Program to check given character is vovel or not
import java.util.*;
class vovel{
public static void main (String args[]){
string ch;
Scanner sc=new Scanner (System.in);
System.out.println("enter any character");
ch=sc.next();
switch(ch){
case "a" : case "e" : case "i": case "o":
case"u": System.out.println("vovel"); break;
default : System.out.println("consonent");
}}}
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