The Ultimate FREE Java Course Part 1

The FREE Java Course
that doesn’t SUCK
Part 1

Agenda
1. Memory Organization
2. Data Hierarchy
3. Types of programming languages
4. Hello World
5. Steps to Run A Java Program
6. Type Conversions

Agenda
7. Operators
1. Arithmetic
2. Relational
3. Assignment
4. Increment/Decrement
5. Logical

Agenda
8. If
9. Ternary Operator
10. for
11. while
12. do while
13. break
14. continue

Agenda
15. Strings
16. String Builder & Conversions
17. Methods & Types of methods
18. Method Overloading
19. Variable Scope
20. Arrays

Where do I watch these videos?
coursetro.com

Mouse
Display
Printer
Keyboard
Main
Memory
Secondary
Storage
CPU
Control Unit
ALU
CPU Storage
Input
Devices
Output
Devices

0
0 0 0 0 0 0 0 0 0 1 0 1 0 1 1 0
1
V i v z
Vivz 26
Vivz 26
Gary 32
Anky 26
Bit
Unicode
Letter V
Field
File
Record
or
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+1300042774
+1400593419
+1200274027
load pay
add overtime
store total
total = pay + overtime
Machine Level Assembly Level High Level
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Install Java JDK
On Windows
Install Java JDK
On Mac
Install IntelliJ On
Windows
Install IntelliJ On
Mac
Relevant
Videos
Click To Watch Videos Below

Google It!
• ASCII table
• unicode table
• ASCII vs Unicode
• utf-8 means
• utf-8 vs utf-16
• machine level language vs assembly language

“Hello World”
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println(“Hello World”);
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System.out.println(“Hello World”);
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1. println in Java
2. system.out.println
3. java system class
4. java String
5. java main method
6. string args in java
7. void in java
Google It!

5 steps to
run a Java
program
Create
Compile
LoadVerify
Run

Create
Editor Disk
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Compile
Compiler Disk
javac HelloWorld.java -> HelloWorld.class
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Load
Class Loader
Disk
Primary
Memory
java HelloWorld
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Verify
Bytecode Verifier
Primary
Memory
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Run
Java Virtual
Machine (JVM)
Primary
Memory
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Memory
Organization And
Data Hierarchy
Hello World
Explained
Hello World
Example
Steps To Run A
Java Program
Relevant
Videos

1. list of java editors
2. javac command
3. java command
4. java compiler vs interpreter
5. java classloader
6. java bytecode verifier
7. jvm in java
8. jvm vs jre
9. jvm vs jre vs jdk vs jit
Google It!

What is a variable?
Storage location in a computer program. It has a name and
value. Assign a value to it any number of times.
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byte
short
int
long
2 bytes1 byte 4 bytes 8 bytes

boolean
char
float
double
2 bytesNot precisely defined 4 bytes 8 bytes

byte myByte = 100;
short myShort = 1000;
int myInt = 100000;
long myLong = 1000000;
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float myFloat = 125.124f;
double myDouble = 125.214545544;
char myChar = ‘C’;
boolean condition = true
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What is a constant?
It has a name and a value. You must assign the value while
creating it and cannot change it afterwards.
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Example
final double PI = 3.14159625;
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1. Data types in java
2. java constants
3. java final variable
Google It!

Type Conversion
A small box can be fitted into a bigger box but vice versa is tricky.
Implicit Type Conversion
long
long
int
int
Explicit Type Conversion

Type Conversion
int earthRad = 6371;
long radius = earthRad;
long
int
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Type Conversion
long galaxyRad= 1000000000000000000L;
int radius = (int) galaxyRad;
long
int
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Variables And
Constants
Explained
Variables And
Constants
Example
Typecasting
Explained
Typecasting
Example
Relevant
Videos

Arithmetic Operators
Addition +
Subtraction -
Multiplication *
Division /
Modulus %
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Modulus Operator
• It gives you the remainder between 2 numbers.
5 % 2 = 1
2 * 2 = 4
• 3 % 4 = 3
21 43 5
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Expression
• Expression in Algebra
1 + 2 + 3 + 4+ 5
= 3
5
• Expression in Java
(1 + 2 + 3 + 4+ 5) / 5 = 3
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Operator Precedence
In Java Arithmetic Operators are evaluated in the
following order from first to last
Multiplicative
* / %
Additive
+ -
Example:
3 * 41 + 7 / 3 – 2 % 1 = ((3 * 41) + (7 / 3)) – (2 % 1) = 125.33
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1. explicit typecasting in java
2. implicit typecasting in java
3. integer division in java
4. modulus operator can be applied to which of the following
5. java expression example
6. precedence of operators in java
7. associativity of operators in java
Google It!

Greater Than
boolean result = 5 > 4; //Contains true
int numOne = 5;
int numTwo = 4;
boolean result = numOne > numTwo; //Contains true
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Less Than
boolean result = 5 < 4; //Contains false
int numOne = 5;
int numTwo = 4;
boolean result = numOne < numTwo; //Contains false
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Greater Than Or Equal To
boolean result = 5 >= 4; //Contains true
boolean result = 5 >= 5; //Contains true
int numOne = 5;
int numTwo = 4;
boolean result = numOne >= numTwo; //Contains true
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Less Than Or Equal To
boolean result = 5 <= 4; //Contains false
boolean result = 5 <= 5; //Contains true
int numOne = 5;
int numTwo = 4;
boolean result = numOne <= numTwo; //Contains false
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Equals To
boolean result = 5 == 4; //Contains false
boolean result = 5 == 5; //Contains true
int numOne = 5;
int numTwo = 5;
boolean result = numOne == numTwo; //Contains true
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Not Equals To
boolean result = 5 != 4; //Contains true
boolean result = 5 != 5; //Contains false
int numOne = 5;
int numTwo = 5;
boolean result = numOne != numTwo; //Contains false
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Arithmetic
Operators
Explained
Arithmetic
Operators
Example
Relational
Operators
Explained
Relational
Operators
Example
Relevant
Videos

Assignment
Int result = 95; //Right to Left
int numOne = 5 , numTwo = 4;
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+=
int numOne = 5;
int numTwo = 4;
//numOne = numOne + numTwo;
numOne += numTwo; //Contains 9
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-=
int numOne = 5;
int numTwo = 4;
//numOne = numOne - numTwo;
numOne -= numTwo; //Contains 1
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*=
int numOne = 5;
int numTwo = 4;
//numOne = numOne * numTwo;
numOne *= numTwo; //Contains 20
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/=
int numOne = 9;
int numTwo = 2;
//numOne = numOne / numTwo;
numOne /= numTwo; //Contains 4
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%=
int numOne = 5;
int numTwo = 4;
//numOne = numOne % numTwo;
numOne %= numTwo; //Contains 1
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Increment
int year = 2050;
newYear = year++;
//Contains 2050
newYear = year;
year = year + 1;
int year = 2050;
newYear = ++year;
//Contains 2051
year = year + 1;
newYear = year;
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Decrement
int year = 2050;
newYear = year--;
//Contains 2050
newYear = year;
year = year - 1;
int year = 2050;
newYear = --year;
//Contains 2049
year = year - 1;
newYear = year;
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!
A !A
true false
false true
boolean engaged = false;
boolean notEngaged = !engaged;
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&&
A B A && B
true true true
true false false
false true false
false false false
boolean dcFan = true, marvelFan = true;
if(dcFan && marvelFan){
System.out.println(“You like superheroes…”);
}

||
A B A || B
true true true
True false true
False true true
false false false
boolean dcFan = false, marvelFan = false;
if(dcFan || marvelFan){
System.out.println(“You like some superhero, don’t you?”);
}
else{
System.out.println(“I guess not!”);
}

Assignment
Operators Explained
Assignment
Operators Example
Increment
Decrement And
Logical Operators
Explained
Increment
Decrement And
Logical Operators
Example
Relevant
Videos

if
If you get 90% or more this year I will get
you a bike.
if ( marks >= 90 ) {
System.out.println(“You get a bike”);
}
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if
If you get more than 80% but less than
90% you get a phone.
if (marks >= 80 && marks < 90) {
System.out.println(“You get a phone”);
}
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If else
If you pass, you get a chocolate
Else no video games.
if ( marks >= 40 ) {
System.out.println(“Chocolate yay!”);
} else {
System.out.println(“No video games”);
}
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If else ladder
If marks greater than 90%, you get a bike,
if marks are between 80-90% you get a
phone, otherwise you get a chocolate, if
you failed, then no video games
if ( marks >= 90 ) {
System.out.println(“You get a bike”);
}
else if (marks >=80){
System.out.println(“You get a phone”);
}
else if (marks>=40){
System.out.println(“Chocolate yay!”);
}
else {
System.out.println(“No video games”);
}
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Nested if else
if marks greater than 90 and physical
fitness examination score greater than 80
you get a car else you get a bike
If marks less than 90 go to the gym
if ( marks >= 90 ) {
if (score>=80){
System.out.println(“You get a car”);
}
else {
System.out.println(“You get a bike!”);
}
}
else {
System.out.println(“Go to the gym”);
}
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1. assignment vs equality operator in java
2. == vs = in java
3. java logical operators
4. dangling else problem in java
5. semicolon after if statement in java
6. short circuit evaluation in java
Google It!

Ternary Operator
result = some condition ? An expression
that returns some value if true : An
expression that returns some value if it is
false;
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Ternary Operator
int marks = 91;
char grade = marks >= 90 ? ‘A’ : ‘B’;

If Else Explained If Else Example
Ternary
Explained
Ternary Example
Relevant
Videos

Case Study
If it is the first day, it is a Sunday… the second day is a
Monday...the last day is a Saturday...anything else is not a day
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int day = 1;
if(day == 1){
… (“It is a Sunday”);
} else if (day == 2) {
… (“It is a Monday”);
}
…
else {
… (“Not a valid day”);
}
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int day = 1;
switch(day){
case 1:
… (“It is a Sunday”);
break;
case 2:
… (“It is a Monday”);
break;
default:
… (“Not a valid day”);
break;
}
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1. break default java
2. switch fallthrough java
3. switch case expressions must be constant expressions
4. switch vs if else performance java
5. switch statement break after default
Google It!

Print Hello World 4 times : The Noob
Way
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for
for( initial value; loop continuation condition; increment) {
//…something that you want to do a certain number of times
}
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Print “Hello World” 4 times
for(int i = 0; i < 4; i++){
…("Hello World");
}
Initialization Check Condition Run the code inside Increment
i = 0 0 < 4 = true Hello World i = 1
1 < 4 = true Hello World i = 2
i = 3Hello World2 < 4 = true
4 < 4 = false
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for(int i = 1; i <= 4; i++){
…("Hello World");
}
Initialization Check Condition Run the code inside Increment
i = 1 1 <= 4 = true Hello World i = 2
2 <= 4 = true Hello World i = 3
i = 4Hello World3 <= 4 = true
4 <= 4 = true Hello World i = 5
5 <= 4 = false
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for(int i = 4; i > 0; i--){
…("Hello World");
}
Initialization Check Condition Run the code inside Decrement
i = 4 4 > 0 = true Hello World i = 3
3 > 0 = true Hello World i = 2
i = 1Hello World2 > 0 = true
1 > 0 = true Hello World i = 0
0 > 0 = false
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Vary the control variable from 1 to 10 in increments of 1.
for (int i = 1; i <= 10; i++)
Vary the control variable from 10 to 1 in decrements of 1.
for (int i = 10; i >= 1; i--)
Vary the control variable from 6 to 66 in increments of 6.
for (int i = 6; i <= 66; i += 6)
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Vary the control variable from 30 to 3 in decrements of 3.
for (int i = 30; i >= 3; i -= 3)
Vary the control variable over the values 3, 7, 11, 15, 19.
for (int i = 3; i <= 20; i += 4)
Vary the control variable over the values 100, 89, 78, 67, 56, 45, 34, 23, 12
for (int i = 100; i >= 10; i -= 11)
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Switch Explained Switch Example
For Explained For Example
Relevant
Videos

1. java for statement
2. java for statement multiple conditions
3. java for statement colon
4. java nested for loop number pyramid
5. java nested for loop exercises
6. java for loop off by one
7. java infinite for loop
Google It!

while
while( some condition is true ) {
//…something that you want to do
}
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int i = 0;
while(i < 4){
…("Hello World");
i++;
}
Initialization Check Condition Run the code inside
i = 0 0 < 4 = true Hello World i = 1
i = 3Hello World2 < 4 = true
4 < 4 = false
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Print “Hello World” Till
Condition Becomes False
boolean condition = true;
int i = 0;
while(condition){
…("Hello World");
i++;
if(i == 4){
condition = false;
}
}
Initialization Condition Run the code inside
i = 0 true Hello World i = 1
true Hello World i = 2
i = 3Hello Worldtrue
true Hello World i = 4
false
Increment if
1 == 4 is false
2 == 4 is false
3 == 4 is false
4 == 4 is true
So make
condition = false

1. java while loop
2. java nested while loop
3. infinite while loop in java
4. while vs for loop java
Google It!

do…while
do{
//…something that you want to do
}
while( some condition is true );
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int i = 0;
do
{
…("Hello World");
i++;
}
while(i < 4);
Initialization Check ConditionRun the code inside
i = 0 Hello World i = 1 1 < 4 = true
Hello World i = 2
i = 3Hello World
2 < 4 = true
3 < 4 = true
Hello World i = 4 4 < 4 = false
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while vs. do…while
boolean condition = false;
while(condition){
…(“Hello World”);
}
//Prints nothing
boolean condition = false;
do{
…(“Hello World”);
}
while(condition);
//Prints Hello World
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While Explained While Example
Do While
Explained
Do While
Example
Relevant
Videos

1. do while loop in java
2. do while vs while java
3. for vs while vs do while
4. infinite do while loop java
5. do while semicolon java
Google It!

break
Break the cases in a switch
Break loops
Labelled break (covered in code)
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Break the cases of a switch
int day = 0;
switch(day){
case 0:
…(“Sunday”);
case 1:
…(“Monday”);
case 2:
…(“Tuesday”);
}
Output
Sunday
Monday
Tuesday
int day = 0;
switch(day){
case 0:
…(“Sunday”);
break;
case 1:
…(“Monday”);
break;
case 2:
…(“Tuesday”);
break;
}
Output
Sunday
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Break Loops
for(int i = 0; i < 9 ; i++) {
…(i);
if(i == 3){
break;
}
}
Output
0
1
2
3
int i = 0;
while(i < 9) {
…(i);
if(i == 3){
break;
}
i++;
}
Output
0
1
2
3
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continue
Skip an iteration in the loops with or
without a label.
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for(int i = 0; i < 9 ; i++) {
if(i == 3){
continue;
}
…println(i);
}
Output
0
1
2
4
5
6
7
8
int i = 0;
while(i < 9) {
i++;
if(i == 3){
continue;
}
…println(i);
}
Output
1
2
4
5
6
7
8
9 coursetro.com

Break Explained Break Example
Continue
Explained
Continue
Example
Relevant
Videos

1. break statement in java
2. break out of loops java
3. labelled break in java
4. continue statement in java
5. break vs continue in java
6. labelled continue in java
Google It!

What are Strings
Strings are simply a sequence of characters defined inside “”
Examples:
“Hello”
“123”
“!@#$%^&*(”
“NB *(*(&GB86786rfyv”
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Kinds of Strings in Java
• String
• StringBuilder
• StringBuffer
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Creating a String
• String str = “Hello String”;
• String nullStr = null;
nullStr = “Hello String”;
• String newStr = new String(“Hello String”);
• String string = String.valueOf(“Hello String”);
Using String class
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Length
String str = “Hello World”;
System.out.println(str.length()); // 11
H e l l o W o r l d
0 1 2 3 4 5 6 7 8 9 10

Concatenating Strings
String str = “Hello”; // Hello
str += “World”; // Hello World
str = str + “!”; // Hello World !
str.concat(“ Again”); // Hello World ! Again
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Escape Sequences
’
””

n
t
…
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Whose equal?
String s1 = “Hello”;
String s2 = “Hello”;
String s3 = “Bye”;
String s4 = new String(“Hello”);
String s5 = “hello”;
s1 == s2 ; // true
s1 == s4; // false
s1.equals(s4); // true
s1.equalsIgnoreCase(s5); // true
s1.equals(s3); // false
Hello
Bye
Hello
hello
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str.indexOf('e');// 1
str.indexOf("ello"); // 1
str.indexOf('o', 5); // 7
str.charAt(3); // l
str.substring(3); // lo World
H e l l o W o r l d
0 1 2 3 4 5 6 7 8 9 10
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str.substring(3, 9); // lo Wor
str.contains("Z"); // false
"".isEmpty(); // true
str.toUpperCase(); // HELLO WORLD
str.toLowerCase(); // hello world
H e l l o W o r l d
0 1 2 3 4 5 6 7 8 9 10
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“ Hello ”.trim(); // Hello
"Potatoes, Apples, Oranges".split(","); //
[“Potatoes”, “Apples”, “Oranges”]
str.join(",", "Apples", "Oranges", "Potatoes"); //
“Apples,Oranges,Potatoes”
H e l l o W o r l d
0 1 2 3 4 5 6 7 8 9 10
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1. java string class
2. java String.valueOf
3. java string length
4. java string concat
5. string concat vs + in java
6. java escape special
characters
7. java string equals
8. equals vs == in java
8. java string indexof
9. java string
equalsignorecase
10. java string charat
11. java string substring
12. java string contains
13. java check empty string
14. java string trim
15. Java string join
Google It!

Creating a String Builder
StringBuilder sb= new StringBuilder();
sb.append("Hello");
StringBuilder sb= new StringBuilder("Hello Again");
StringBuilder sb= new StringBuilder(5);
sb.append("Hello One more time");
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Length
StringBuilder sb = new StringBuilder(“Hello World”);
System.out.println(sb.length()); // 11
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Concatenation
StringBuilder sb = new StringBuilder("Hello"); // Hello
sb.append(“World”); // Hello World
sb.append(“!”); // Hello World !
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Methods
StringBuilder sb = new StringBuilder("Hello"); // Hello
sb.append(" Again"); // Hello Again
sb.insert(5, "2"); // Hello2 Again
sb.replace(5, sb.length(), " World"); // Hello World
sb.delete(5, 11); // Hello
sb.deleteCharAt(4); // Hello coursetro.com

Conversions to String
byte b = 1;
String result = String.valueOf(b);
short s = 12;
String result = String.valueOf(s);
String result = String.valueOf(123);
char letter = ‘A’;
String result = String.valueOf(letter); coursetro.com

Conversions to String
long l = 1224;
String result = String.valueOf(l);
String result = String.valueOf(23.32f);
String result = String.valueOf(12.34);
String result = String.valueOf(true); coursetro.com

Conversions from String
String value = “12”;
byte b= Byte.parseByte(value);
short s= Short.parseShort(value);
int i = Integer.parseInt(“123”);
String value = “A”;
char c =value.charAt(0); coursetro.com

Conversions from String
long l = Long.parseLong(value);
float f= Float.parseFloat(“23.42F”);
double d = Double.parseDouble(“12.3456”);
boolean b =Boolean.parseBoolean(“false”);

Click to watch videos below
String Explained String Example I
String Example
II
String Builder
And String
Conversions
Explained
String Builder
And String
Conversions
Example

1. java stringbuffer class
2. java stringbuilder class
3. string vs stringbuffer
4. string vs stringbuilder
5. stringbuffer vs
stringbuilder
6. stringbuilder append
7. stringbuilder delete
8. stringbuilder insert
9. stringbuilder replace
10. stringbuilder to string
11. integer.parseint
12. float.parsefloat
13. double.parsedouble
14. string.valueof
Google It!

What are methods ?
A group of instructions that which you can name.
Calling the name runs all the instructions in that group.
Sure Boss.
Send that email
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Another example
main()
Math.pow()Send 2 and 3
Calculate 23
Give result
Use result

Add 2
numbers
without
methods
Add 2 + 5
int num1 = 2, num2 = 5;
int sum = num1 + num2;
Add 3 + 7
int num1 = 3, num2 = 7;
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Why repeat
yourself?
Bunch the 2 lines together!
{
int num1 = 2, num2 = 5;
}
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Give that
bunch a
name
add(){
int num1 = 2, num2 = 5;
}
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Call the
name() to add
2 + 5 every
time
add();
Its like calling your assistant
Wait, who wants to add 2 + 5 every
time?
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Tell them
what to add
while calling
them
add(3, 7)
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Assistant
says, “Give
me the
numbers, I
will add
them”
add(int num1, int num2){
}
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What should
the assistant
do after
adding?
Display the result?
Print them on a printer?
Email the boss?
Why not tell your assistant to give
the results back to the boss?
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Assistant says
it will return
an integer
int add(int num1, int num2){
return sum;
}
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Boss is free
to do
whatever
he/she wants
with the
result
int result = add(3, 7);
…println(result);
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Assistant says
“I will display
the value but
I wont give
the boss any
result”
void add(int num1, int num2){
…println(sum);
}
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Boss calls the
assistant to
display the
result
add(3, 7);
The assistant’s code has a println()
remember?
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1. java methods example
2. java method vs function
3. java method signature
4. java argument promotion and casting
5. java method overloading
6. java method call stack
Google It!

Kinds of Methods
• Methods that take no input and give no result back.
• Methods that take input and give no result back.
• Methods that take no input and give some result back.
• Methods that take input and give some result back.
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No instructions, no reporting
Boss Assistant
sendEmail() public void sendEmail(){
//code written to send email
}
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No instructions, With reporting
Boss Assistant
boolean outcome = public boolean sendEmail(){
//code written to send email
return success;
}
Reporting
sendEmail()
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Instructions included, no reporting
Boss Assistant
sendEmail(
“contact@coursetro.com”,
”Hello”,
“I would love to buy your course”)
public void sendEmail(String to,
String subject, String message){
//code written to send email to the
//person with the subject and message
}
Instructions
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Instructions included, With reporting
Boss Assistant
boolean outcome = public boolean sendEmail(String to,
return success;
}
Instructions
Reporting
sendEmail(
”Hello”,
coursetro.com

Assistant handling 1 set of instructions
Boss Assistant
Instructions [to whom, subject, message]
Reporting
coursetro.com

New assistant for email with
attachments?
coursetro.com

Multiple assistants with same name
Boss Assistant
Instructions [to whom, subject, message]
Reporting
Instructions [to whom, subject, message, attachment]
coursetro.com

Boss Assistant
boolean outcome = sendEmail(
”Hello”,
//OR
public boolean sendEmail(String to,
return success;
}
Instructions
Reporting
boolean outcome =
sendEmail(
”Hello”,
“I would love to buy your
course”,
…)
public boolean sendEmail(String to,
String subject, String message, Object attachment){
return success;
}
coursetro.com

What is variable scope?
Scope = part of the program where you can access your
variable…
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Example 1
public static void main(String[] args){
System.out.println(volumeOfCube(10.0));
}
public static double volumeOfCube(double length){
return length * length * length;
}
length is called a local variable and can be accessed or used only inside the blue box
Scope = within {} where it was created

Example 2
Both i and square can be accessed or used only inside the green box
Scope = within {} where it was created
int sum = 0;
}
for(int i = 0 ; i <= 10 ; i++ ) {
int square = i * i;
sum = sum + square;
}

Same variable name in different scopes
int result = square(5);
};
public static double square(int number){
int result = number * number;
return result;
}
Variables created inside different boxes can have the same name

Click to watch videos below
Methods
Explained
Types of
Methods
Methods
Example
Method
Overloading And
Variable Scope
Explained
Method
Overloading And
Variable Scope
Example

1. java method variable scope
2. java method overloading
3. java method overloading rules
Google It!

What is an array ?
It’s a collection of variables of fixed size and same type.
Collection of integers.
Collection of Booleans
Collection of Characters
1 52 0
true falsefalse true
‘c’ ‘r’‘q’ ‘t’

Representation of an Array
Every item in an Array has a location
Location starts from 0, not 1
Length = 9, last position in the above array = 8
In Memory
Locati
on
0 1 2 3 4 5 6 7 8
Value C o u r s e t r o
coursetro.com

Method A
int[] numbers;
numbers =
coursetro.com

Method A
int [] numbers;
numbers = new int[10];
int[]
0
0
0
0
0
0
0
0
0
0

Method A
int [] numbers;
numbers = new int[10];
numbers[5] = 26;
int[]
0
0
0
0
0
26
0
0
0
0
0
1
2
3
4
5
6
7
8
9

Method B
int[] numbers = {0, 0, 45, 18}; int[]
0
0
45
18
0
1
2
3
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Array References
int[] scores = {10, 9, 7, 6, 8};
int[] values = scores;
scores[3] = 10;
System.out.println(values[3]); //Prints 10
int[]
10
9
7
6
8
0
1
2
3
4
scores =
values =
10
9
7
10
8
0
1
2
3
4
coursetro.com

Reading values from Arrays.
Using for loop:
int[] numbers = {4,1,5,7,8};
for( int i = 0 ; i < numbers.length ; i++ )
{
…(“Value at index ” + i + “ is: “ + numbers[i] );
}
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Using while loop:
int[] numbers = {4,1,5,7,8};
int counter = 0;
while( counter < numbers.length ){
…(“Value at index ” + i + “ is: “ + numbers[i] );
counter += 1;
}
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Using for-each loop:
int[] numbers = {4,1,5,7,8};
for( int i : numbers )
{
…(“Value “ + i );
}
coursetro.com

Send email to an array of addresses
Boss Assistant
String[] to = {
“slidenerd@gmail.com”,
”contact@designcourse.com”};
sendEmail(to)
public void sendEmail(String[] to){
//code written to send ‘hello there’
//email to the person
}
Instructions
coursetro.com

Send and receive arrays from a method
Boss Assistant
String[] to = {
“slidenerd@gmail.com”,
”contact@designcourse.com”};
boolean[] outcomes = sendEmail(to)
public boolean[] sendEmail(String[] to){
boolean[] successes = …
//code written to send hello to everyone
return successes;
}
Instructions
Reporting
coursetro.com

1. java array with variable size
2. java array declaration
3. java array initialization
4. where are arrays stored in memory in java
5. java string array
6. java character array
7. char array to string java
8. string to char array java
9. java for each loop
Google It!

Single dimensional Array
int[] numbers = {9,8,7,6}; int[][] numbers = {
{9,8,7},
{6,5,4},
{3,2,1}
};
Position 0 1 2 3
Value 9 8 7 6
Position Col 0 Col 1 Col 2
Row 0 9 8 7
Row 1 6 5 4
Row 2 3 2 1

Multi dimensional Array
int[][] numbers;
numbers = new int[3][3];
numbers[0][0] = 9;
…
numbers[2][2] = 1;
Row 0 9 8 7
Row 1 6 5 4
Row 2 3 2 1
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Print column wise
We want to print:
column 0, column 1, column 2 for row 0
We want to print
column c for row r
Row 0 9 8 7
Row 1 6 5 4
Row 2 3 2 1
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Print column wise
If we wanted to print only the first row:
for(int c = 0; c < 3; c++){
…(numbers[0][c]);
}
Row 0 9 8 7
Row 1 6 5 4
Row 2 3 2 1
coursetro.com

Print column wise
If we wanted to print all rows and all columns:
for(int r = 0; r < 3; r++){ //Increase the rows by 1 after inner loop runs
for(int c = 0; c < 3; c++){ //Increase the column by 1 each time
…(numbers[r][c]);
}
}
Row 0 9 8 7
Row 1 6 5 4
Row 2 3 2 1
coursetro.com

Multidimensional Array
0 1 2
0 9 8 7
1 6 5 4
2 3 2 1
Jagged Array
0
1
2
9
8
6
7
5 4
0 1 2
int[][] numbers = new int[3][3];
numbers[0][0] = 9;
…
numbers[2][2] = 1;
int[][] numbers = new int[3][ ];
numbers[0] = new int[1];
numbers[0][0]=9;
…
numbers[2][2]=4;
coursetro.com

Arrays Explained Arrays Example
Multidimensional
Arrays Explained
Multidimensional
Arrays Example
Relevant
Videos

1. java multidimensional array
2. Java multidimensional array length
3. java jagged array
4. java jagged array length
Google It!

What Next?
Part 2 covers all Object Oriented Stuff, search for it J

Thank You From…
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