The conditional control statement controls the order in which a java program is executed.
Types of Conditional control statement:
If statement
Switch statement
Syntax :
i) if(condition){
s1;
}
ii) if(condition){
s1;
}
else{
s2;
}
iii) if (condition) {
s1;
} else
if (condition) {
s2;
} else {
s3;
}
package com.javabykiran.basics;
public class Lab12 {
public static void main(String[] args) {
int a = 5;
int b = 2;
int c = 1;
if ((a > b) && (a > c)) {
System.out.println("Min" +a);
} else if (b > c) {
System.out.println("Min" +b);
} else {
System.out.println("Min" + c);
}
if (a < b) {
if (a < c) {
System.out.println("Min:" +a);
} else {
System.out.println("Min" + c);
}
} else {
if (b < c) {
System.out.println("Min" +b);
} else {
System.out.println("Min" + c);
}
}
}
}
Syntax :
switch(expr) {
case No1: s1;
break;
case Non: sn;
break;
default: s;
}Example:
package com.javabykiran.basics;
public class Lab16 {
public static void main(String[] args){
int a = Integer.parseInt(args[0]);
switch (a) {
case 1:
System.out.println("FRI");
break;
case 2:
System.out.println("MON");
break;
case 3:
System.out.println("TUE");
break;
default:
System.out.println("Invalid No");
break;
}
}
}
NOTE: The default statement can be written anywhere in the switch statement. But they have a break. In the last statement, it does not have break, but it is also possible.
Looping statements execute statements over and over again, in a loop. It continues until the condition result is true.
Types of Looping control statement:
For statement
While statement
Do while statement
The for statement lets a code execute in a loop continuously.
Syntax :
for (initialization; condition; increment/decrement) {
s1; s2;
}
for( ; ; ) { // possible empty
s1; s2;
}
package com.javabykiran.basics;
public class Lab17 {
public static void main(String[] args) {
int n = 67;
System.out.println("Forward order");
for (int i = 1; i <= n; i++){
if (i % 5 == 0) {
System.out.println(i);
}
}
System.out.println("Reverse order");
for (int i = n; i >= 1; i--){
if (i % 5 == 0) {
System.out.println(i);
}
}
}
}
Output:
Forward order
5
10
15
20
25
30
35
40
45
50
55
60
65
Reverse order
65
60
55
50
45
40
35
30
25
20
15
10
5
package com.javabykiran.basics;
/*
Prime Numbers Java Example:
This example shows how to generate prime numbers
between 1 and the given number, using a for
loop.
*/
public class GeneratePrimeNumbersExample {
public static void main(String[] args){
// define limit
int limit = 100;
System.out.println("Prime numbers between 1 and " +limit);
// loop through the numbers one by one
for (int i = 1; i < 100; i++) {
boolean isPrime = true;
// check to see if the number is prime
for (int j = 2; j < i; j++) {
if (i % j == 0) {
isPrime = false;
break;
}
}
// print the number
if (isPrime)
System.out.print(i + " ");
}
}
}
/*
* Output of Prime Numbers example would be Prime numbers between 1 and 100 12
*3 5 7 11 13 17 19 23 29 31 37 41 43 47 53 59 61 67 71 73 79 83 89 97
*/
package com.javabykiran.basics;
public class Lab19 {
static Boolean isPrime(int n) {
int count = 0;
for (int i = 2; i <= n / 2; i++) {
if (n % i == 0) {
count++;
break;
}
}
if (count == 0) {
return true;
} else {
return false;
}
}
public static void main(String[] args) {
int m = 3;
int n = 30;
for (int i = m; i <= n; i++) {
boolean b = isPrime(i);
if(b){
System.out.println(i);
}
}
}
}
Output:
3
5
7
11
13
17
19
23
29
The while statement executes a single line continuously until the condition is met.
Syntax :
initialization;
while(condition) {
s1;
s2;
Increment/decrement
}Example :
package com.javabykiran.basics;
public class Lab22 {
public static void main(String[] as) {
int n = Integer.parseInt(as[0]);
//int n = 10;
System.out.println("Forward order");
int i = 1;
while (i <= n) {
if (i % 5 == 0) {
System.out.println(i);
}
i++;
}
System.out.println("Reverse order");
i = n;
while (i >= 1) {
if (i % 5 == 0) {
System.out.println(i);
}
i--;
}
}
}
Output:
Forward order
5
10
Reverse order
10
5
package com.javabykiran.basics;
public class Lab33 {
public static void main(String[] args){
int n = 123;
// int n=Integer.parseInt(args [0]);
int sum = 0;
while (n != 0) {
int r = n % 10;
sum += r;
n = n / 10;
}
System.out.println("Sum = " + sum);
}
}
Output:
Sum = 6
The do while statement executes a particular chunk of the code until a Boolean expression is true.
Syntax :
Initialization;
do {
//processing s2;
Increment/decrement
} while ( condition );Example:
package com.javabykiran.basics;
public class Lab20 {
public static void main(String[] args) {
int n = 30;
System.out.println("while");
int i = 1;
while (i <= n)
System.out.println("ok" + i);
if (i% 5 == 0) {
System.out.println(i);
}
i++;
System.out.println("do_While");
i = 1;
do {
if ((i % 5) == 0) {
System.out.println(i);
}
i++;
System.out.println("ok" +i);
} while (i <= n);
}
}
| While | Do While |
|---|---|
| In the case of While, the first condition will be verified and then the statement will be executed, Inside the while block. | In the case of Do-While first statement, inside do block is executed and the condition is be verified. |
| If the condition is false the first time, then the block of statement will be executed zero times. | If the condition is false the first Time, then the block of statement will be executed once. |
Types of Unconditional control statements:
Break
Continue
Goto
Break statement transfers the control unconditionally to the end of the block.
The Continue statement transfers the control unconditionally to the beginning of the block.
Example:
package com.javabykiran.basics;
public class Lab23 {
public static void main(String[] args) {
int n=12;
for(int i=1; i < n; i++) {
if(i %2==0){
System.out.println(i+" Next is continue");
continue;
}
else if(i==9) {
System.out.println("i is 9");
break;
}
System.out.println("Ok "+i);
}
System.out.println("Done");
}
}
Output:
Ok 1
2 Next is continue
Ok 3
4 Next is continue
Ok 5
6 Next is continue
Ok 7
8 Next is continue
i is 9
Done
Example:
package com.javabykiran.basics;
public class Lab24 {
public static void main(String[] args){
/*
* if(1) { } while(1) { -- }
*/
int i = 1;
/*
*for(i<=3)
sop(i);
i++; } /* while(true) sop("ok");}
*/
// System.out.println("Done");
}
}
package com.javabykiran.basics;
public class Lab25 {
public static void main(String[] args) {
for (int i = 1; i <= 2; i++){
JBK: for (int j = 1; j <= 2; j++) {
for (int k = 1; k <= 2; k++){
if (k <= 3)
System.out.println(k + "\t");
else
break JBK;
} // end of k for
System.out.println("JBK");
} // end of j for
System.out.println("*");
} // end of i for
System.out.println("Done");
}
}
Output:
1
2
JBK 1
2
JBK
* 1
2
JBK 1
2
JBK
* Done