Java Conditional and Loop Statements

Java Conditional and Loop Statements

Java Flow Control
i) Java Conditional Statements
2) Java Loop Statements
————————————————————–
i) Java Conditional Statements
> Conditional Statements are used to insert verification points and error handling.

a) Two types of Conditional statements in Java
1) if statement

2) switch Statement
————————
b) Types of Conditions
1) Single Condition (Positive and Negative Conditions)

Ex:

if (a > b) {
—–
—-
}
—————
if (!(a < b)){
——
———-
}
——————–
2) Compound Condition

Ex:

if ((a > b) && (a < C)){
——–
——–
}

if ((a > b) || (a < C)){
——–
——–
}
——————————
3) Nested Condition

if (a>b){
if (a>c){
if (a>d){
}
}
}
———————————-
c) Usage of Conditional Statements
1) Execute a block of statements when condition is True.
Syntax:

if (Condition){
Statements
——–
———
——
}

Example:

public class Flow Control {
public static void main (String []args){

int a, b;
a=50; b=200;

if (a > b){
System.out.println(“A is a Big Number”);
}
}
}
——————————
2) Execute a block of statements when a compound Condition is True.
Syntax:

if ((Condition1) && or || (Condition2)) {
Statements
———
———
}

Example:

public class FlowControl {
public static void main (String []args){

int a, b, c;
a=50; b=40; c=30;

if ((a > b) && (a > c)) {
System.out.println(“A is a Big Number”);
}
}
}
—————————-
3) Execute a block of statements when condition is True, otherwise execute another block of statements.
Syntax:

if (Condition) {
Statements
———
———
}
else
{
Statements
———
———
}

Example:

public class FlowControl {
public static void main (String []args){
int a, b;
a=50; b=50;

if (a > b){
System.out.println(“A is a Big Number”);
}
else
{
System.out.println(“B is a Big Number”);
}
}
}
——————————
4) Decide among several alternates (else if structure)
Syntax:

if (Condition){
Statements
———–
}
else if (Condition) {
Statements
———–
}
else if (Condition) {
Statements
———–
}
else if (Condition) {
Statements
———–
}
else
{
Statements
———–
}

Example:

Initialize a integer variable, and Verify the Number.

if the number is in between 1 and 100 then display number is a Small Number.

if the number is in between 101 and 1000 then display number is a Medium Number.

if the number is in between 1001 and 10000 then display number is a Big Number.

if the number is more than 10000 then display number is High Number.

Otherwise display Number is either Zero or Negative number.
——————————————————
public class FlowControl {
public static void main (String []args){
int a =-100;

if ((a >= 1) && (a <= 100)){
System.out.println(“A is a Small Number”);
}
else if ((a > 100) && (a <= 1000)){
System.out.println(“A is a Medium Number”);
}

else if ((a > 1000) && (a <= 10000)){
System.out.println(“A is a Big Number”);
}
else if (a > 10000) {
System.out.println(“A is High Number”);
}
else
{
System.out.println(“A is either Zero or Negative Number”);
}
}
}
——————————————
5) Execute a block of statements when more than one condition is True.
Syntax:

if(Condition){
if(Condition){
if(Condition){
Statements
——–
——–
}

}

}
———————————
Examples:
—————————-
i) Else part for 1st condition only

public class FlowControl {
public static void main (String []args){
int a =10, b=80, c=7, d=2;

if (a> b){
if (a>c){
if (a>d){
System.out.println(“A is a Big Number”);
}
}
}
else
{
System.out.println(“A is Not a Big Number”);
}
}
}
———————————-
ii) Else part for 2nd condition only

if (a> b){
if (a>c){
if (a>d){
System.out.println(“A is a Big Number”);
}
}
else
{
System.out.println(“A is Not a Big Number”);
}
}
———————
iii) Else part for 3rd condition only

if (a> b){
if (a>c){
if (a>d){
System.out.println(“A is a Big Number”);
}
else
{
System.out.println(“A is Not a Big Number”);
}
}
}
————————–
iv) Else parts for all conditions

public class FlowControl {
public static void main (String []args){
int a =10, b=8, c=7, d=2;

if (a> b){
if (a>c){
if (a>d){
System.out.println(“A is a Big Number”);
}
else
{
System.out.println(“A is Not a Big Number”);
}
}
else
{
System.out.println(“A is Not a Big Number”);
}
}
else
{
System.out.println(“A is Not a Big Number”);
}
}
}
————————————–
Get Biggest number out of Four Numbers (else if and compound conditions)
public class FlowControl {
public static void main (String []args){
int a =10, b=8, c=7, d=2;

if ((a>b) && (a>c) && (a>d)){
System.out.println(“A is a Big Number”);
}
else if (((b>a) && (b>c) && (b>d))) {
System.out.println(“B is a Big Number”);
}
else if (((c>a) && (c>b) && (c>d))) {
System.out.println(“C is a Big Number”);
}
else{
System.out.println(“D is a Big Number”);
}
}
}
—————————–
6) Decide among several alternates (using Switch case structure)
Syntax:

switch (expression) {
case value:
Statements
——-
——-
break;
case value:
Statements
——-
——-
break;
case value:
Statements
——-
——-
break;

default
Statements
———
———
———-
}
———————————
Example:

public class FlowControl {
public static void main (String []args){
char grade= ‘X’;

switch (grade){

case ‘A’:
System.out.println(“Excellent”);
break;

case ‘B’:
System.out.println(“Well Done”);
break;

case ‘C’:
System.out.println(“Better”);
break;

default:
System.out.println(“Invalid Grade”);
}
}
}
————————————————————–
ii) Java Loop Statements
Loop statements for repetitive execution.

a) for loop

b) while loop

c) do while loop

d) Enhanced for loop
—————————————–
a) for loop
Description: It repeats a block of statements for a specified number of times.

Syntax:

for (stratValue; endValue; increment/decrement){
Statements
——-
——-
}

Example1:
//Print 1 to 10 Numbers

for(int i=1; i<=10; i++){
System.out.println(i);
}
—————————–
Example2:
//Print 10 to 1 Numbers

for(int i=10; i>=1; i–){
System.out.println(i);
}
———————————-
Example3:
//Print 1 to 10 Numbers except 7

for(int i=1; i<=10; i++){
if (i != 7){
System.out.println(i);
}
—————————————–
Example4:
//Print 1 to 10 Numbers except 4th number and 7th Number

for(int i=1; i<=10; i++){
if ((i != 4) && (i != 7)){
System.out.println(i);
}
}
———————————————-
b) while loop
Description: It repeats a block of statements while condition is true.

Syntax:

Initialization
while (Condition){
statements
——–
——-
increment/decrement
}

Example1:
//Print 1 to 10 Numbers

int i = 1;
while (i <= 10){
System.out.println(i);
i++;
}
———————————-
Example2:
//Print 10 to 11 Numbers

int i = 10;
while (i >= 1){
System.out.println(i);
i–;
}
}
——————————-
Example3:
//Print 1 to 10 Numbers except 7

int i = 1;
while (i <= 10){
if (i != 7){
System.out.println(i);
}
i++;
}
—————————————–
c) do while loop
Description: It repeats a block of statements while condition is true.
It executes a block of statements at least once irrespective of the condition.

Syntax:

Initialization
do
{
Statements
———
———
increment/decrement
} while (Condition);

Example:

int i = 1;
do
{
System.out.println(i);
i++;
} while (i<=10);
———————————–
int i = 20;
do
{
System.out.println(i);
i++;
} while (i<=10);
——————————————-
d) Enhanced for loop
It Executes all elements in an Array.

Syntax:

Array Declaration

for (declaration: Expression/Array){
Statements
——
}

Examples:

String [] languages ={“C”, “COBOL”, “Java”};

for (String lang: languages){
System.out.println(lang);
}
———————————-
String [] languages = new String[3];
languages[0] =”C”;
languages[1] =”COBOL”;
languages[2] =”Java”;

for (String lang: languages){
System.out.println(lang);
}
—————————————
int [] mathOperations = new int[3];
int a=10, b=20;

mathOperations[0]= a+b;
mathOperations[1]= a-b;
mathOperations[2]= a*b;

for (int operation: mathOperations){
System.out.println(operation);
}
———————————————
double [] mathOperations = new double[4];
double a=10, b=20;

mathOperations[0]= a+b;
mathOperations[1]= a-b;
mathOperations[2]= a*b;
mathOperations[3]= a/b;

for (double operation: mathOperations){
System.out.println(operation);
}
—————————–

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