rupakraj/core-java-examples

Java core examples for beginner

Tranining on Java Core

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Includes the core java basic useful for Android

Tools

• JDK ( OpenJDK or Oracle JDK)
• Text Editor (Any thing- Sublime or Atom or <3 emacs)
• IDE (not recommended :( )

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Language

• How it works? (JDK, JRE, JVM, .java, .class, bytecode)
• write/edit - compile - run (editor, javac, java)
• Type Safe
• Basic Structure
• Comments (Single line or multiline)
• Variables, Data Types (int, char, float, double,bool, String-Refrence Type etc)

data_type <identifier>; // eg int rollNo; //RollNo rollNo roll_no; // No special chars (except _) String name; // value assign => Operation Assignment (=) // Value Type Numeric,char ('SingleQuote') ,String ("Double Quote") rollNo = 10; // declar with initialization String address = "Kathmandu";

• Expression + Operators (+,-,* etc)

float marks_math=123.90, marks_eng =234.09; float avg = (marks_math+marks_eng)/2;

• Statements/Block - terminate by ; / block-{ }
• if..elseif..else, switch

` if(expression){ // true }else{ // false } // evaluation operatiors ( == <= >= < > !(NOT) != AND(&&) OR(||) // !true => false // !false => true // true && true => true otherwise false // false || false => false otherwise true // eg : percent = 89 // percent >=60 && percent < 80 => true

float percent = 89;
if(percent >=60 && percent < 80){
    System.out.println("First Division");
    }
else{
    System.out.println("Other  Division");
    }

// else if
if(percent >=60 && percent < 80){
    System.out.println("First Division");
}
else if(percent >=80) {
    System.out.println("Distincition");
    }
else{
    // else
}

`

• Conditional Operator (? :)
• Iterations: while, for, do-while, foreach

` while (expn){ delay(1006010) // execute this }

while(x==8){ // I can use x here x= x+5-y; }

do{ // this block execute at least once }while(expn)

// for ++, // eg: x++; => x = x+1; // eg: x--; => x = x-1; for(counter-init; counter-evaluate; counter-inc-dec; ){ // loop Body }

`

• Nested Loop
• Array / Object
• Defining Class
• Getter/Setter
• Different ways of creating Objects
• Overloading
• Calling Methods
• Inheritance (extend/implement)
• Example of implement

Generics

• List, ArrayList
• Generic Types

Standard Library

• File handling
• Http handling

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