first commit

Access_modifier/A.java

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+package Access_modifier;
+
+public class A {
+	public void display() {
+		System.out.println("HI I am private");
+	}
+	protected void display2() {
+		System.out.println("Hi I am protected");
+	}
+
+	void nothing() {
+		System.out.println("Default, We can only use in Same package");
+	}
+}

Access_modifier/B.java

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+package Access_modifier;
+
+public class B {
+
+}

Access_modifier/C.java

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+package Access_modifier;
+
+public class C {
+
+}

Access_modifier/test.java

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+package Access_modifier;
+
+public class test {
+ public static void main(String[] args) {
+	A a = new A();
+	a.display();
+	a.display2();
+	a.nothing();
+}
+}

Access_modifier2/CC.java

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+package Access_modifier2;
+
+import Access_modifier.A;
+
+public class CC extends A {
+public static void main(String[] args) {
+	CC aa= new CC();
+	aa.display();
+	aa.display2();
+//	aa.nothing();
+}
+}

ExpressionHandaling/A.java

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+package ExpressionHandaling;
+
+import java.io.File;
+
+public class A {
+
+	// expection handaling
+	// - Runtime Error means expection
+
+	int x = 10;
+	int y = 0;
+	 int z=  x / y; 
+//	 Arithmetic expection
+
+	 String name = null;
+	 char name2 =  name.charAt(0);
+	 //Null pointer expection
+
+	 String name3 = "Dipraj";
+	 char name4 = name3.charAt(9);
+	 // String Index Out Of Bounds Expection
+
+	 int num = Integer.parseInt("DIPURAJ");
+	 // NumberFormet expection
+
+	 File file  = new File("../..///");
+	 //File not Found expection
+
+	 int[] a = new int[5];
+	 a[5] = 32;
+	 //Array INdex Out of bOund expection
+
+	// What is expection handling
+	 // Handling runtime ERROR
+
+//	 try
+//	 catch
+//	 finally
+//	 throw
+//	 throws
+	 //this keywords are used to handle expection
+
+	 try {
+
+		 //code you want to monitor
+//		 or maybe the code can show expection error
+		 //if any expection will have found than try will throw it to the FIRST CATCH
+	 }
+	 catch( /* expection type e1 */ ) {
+		 //Exception handler for expection
+	 }
+	 catch( /* expection type e2 */ )
+	 {
+		 //Exception handler for expection	 //Exception handler for expection
+	 }
+	 finally {
+		 // block of code to be executed after try block
+	 }
+
+
+}

ExpressionHandaling/ExpectionDemo.java

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+package ExpressionHandaling;
+
+public class ExpectionDemo {
+	public static void main(String[] args) {
+
+		try {
+		int x = 10;
+		int y = 0;
+			int result = x/y;
+			System.out.println(result);
+		}
+
+		catch(ArrayIndexOutOfBoundsException e) {
+			System.out.println("Expection : "+e);
+		}
+		catch(ArithmeticException e) {
+			System.out.println("Expection : "+e);
+		}
+
+		finally {
+			System.out.println("Vai jani nah ki vul hocie");
+		}
+
+
+		System.out.println("Last line of the program");
+
+		//Another
+
+		try {
+			int [] a = new int[4];
+			a[4] = 5;
+
+		}
+		catch(ArrayIndexOutOfBoundsException e1) {
+			System.out.println("Expection : "+e1);
+		}
+		catch(Exception e2) {
+			System.out.println("Expection : "+e2);
+		}
+		finally {
+			System.out.println("Last line of the program");
+		}
+
+
+
+	}
+}

HashSett/HashSetDemo.java

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+package HashSett;
+
+import java.util.HashSet;
+
+public class HashSetDemo {
+	public static void main(String[] args) {
+
+		HashSet<String> fruits = new HashSet<String>();
+
+		fruits.add("Alu");
+		fruits.add("Orange");
+		fruits.add("Banana");
+
+		System.out.println(fruits);
+		System.out.println(fruits.size());
+	}
+}

Hashmap/Hashmapp.java

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+package Hashmap;
+
+import java.util.HashMap;
+
+public class Hashmapp {
+	public static void main(String[] args) {
+
+		HashMap<Integer, String> customar = new HashMap<Integer, String>();
+
+		//put get
+		customar.put(101, "Dipraj");
+		customar.put(102, "Sunu");
+		customar.put(130, "Anu");
+
+
+		System.out.println(customar.get(102));
+
+	}
+}

LinkedList/LinkEDLIST.java

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+package LinkedList;
+
+import java.util.LinkedList;
+
+public class LinkEDLIST {
+
+	public static void main(String[] args) {
+
+		LinkedList<String> countryName = new LinkedList<String>();
+
+		countryName.add("Bangladesh");
+		countryName.add("India");
+		countryName.add("Pakistan");
+		countryName.add("China");
+
+		countryName.add(4, "Japan");
+		countryName.add(5, "Argentina");
+
+		countryName.addFirst("USA");
+		countryName.addLast("Afganistan");
+
+		for(String x : countryName) {
+			System.out.println(x);
+		}
+
+		countryName.remove(5);
+		countryName.removeFirst();
+
+
+		System.out.println(countryName);
+		System.out.println("Size of the list : " + countryName.size());
+
+		System.out.println( "5 " + "Element is : "+countryName.get(5));
+
+	}
+
+
+}

LinkedList/StudentList.java

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+package LinkedList;
+
+public class StudentList {
+
+	String name ,className;
+	int id;
+
+	StudentList(int id, String name, String className){
+		this.id = id;
+		this.name = name;
+		this.className = className;
+
+	}
+
+	@Override
+
+	public String toString(){
+		return "ID : " +  id + ", Name : " + name + ", Class : " + className;
+	}
+
+
+}

LinkedList/StudentListDemo.java

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+package LinkedList;
+
+import java.util.LinkedList;
+
+public class StudentListDemo {
+public static void main(String[] args) {
+	// student link list
+
+	LinkedList<StudentList> list = new LinkedList<StudentList>();
+
+
+	// student create
+
+	StudentList s1 = new StudentList(1, "Dipraj", "XI");
+	StudentList s2 = new StudentList(2, "Sun", "XII");
+	StudentList s3 = new StudentList(3 , "Ayaon", "V");
+	StudentList s4 = new StudentList(4, "Avro", "I");
+
+	// adding student
+
+	list.add(s1);
+	list.add(s2);
+	list.add(s3);
+	list.add(s4);
+
+	for(StudentList o : list) {
+		System.out.println(o);
+	}
+}
+}

StringComparison/Compare1.java

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+package StringComparison;
+
+public class Compare1 {
+
+	public static void main(String[] args) {
+	//equals()
+	//Compares the original content of the string 
+
+	String password1 = "Dipraj";
+	String password2 = "Dipraj";
+	String pass3 = new String("Dipraj");
+	String pass4 = new String("Dipraj");
+
+	System.out.println(pass3.equals(pass4));
+	// == compare the reference of the objects not the value
+	System.out.println(password1 == password2); //true
+	System.out.println(password1 == pass3); // false
+	}
+}

ToStringMethod/Person.java

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+package ToStringMethod;
+
+public class Person {
+
+	// to string method
+	String name;
+	int age;
+	Person(String name, int age ){
+		this.age = age;
+		this.name = name;
+	}
+
+	@Override
+	public String toString() {
+		return "Name : " + name + "\n" + "Age : "+ age;
+
+	}
+
+}

ToStringMethod/test.java

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+package ToStringMethod;
+
+public class test {
+	public static void main(String[] args) {
+
+		Person  p1 =new Person("Dipraj",56);
+		Person p2 = new Person("Minhaj", 89);
+		System.out.println(p1); // toString Method
+		System.out.println(p2); //toString method
+	}
+}

TypeCasting/A.java

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+package TypeCasting;
+
+public class A {
+	// to convert data type from one to another
+
+	public static void main(String[] args) {
+		int x = 10;
+		double y = x; //implicit type casting
+		// Widening
+
+
+
+		double z=12.5;
+		int c = (int) z; // explicit type casting
+		//narrowing
+
+		// not primitive type casting
+//		1. Upcasting
+//		2. downcasting 
+
+		Person p = new Teacher(); // upcasting
+		p.display();
+
+		Teacher t = (Teacher) new Person();
+		t.display(); //compile error
+
+		System.out.println(y +" " + c );
+
+	}
+}

TypeCasting/Person.java

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+package TypeCasting;
+
+public class Person {
+
+	// super
+
+	void display() {
+		System.out.println("Perosn class");
+	}
+
+}

TypeCasting/Teacher.java

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+package TypeCasting;
+
+public class Teacher extends Person {
+	//sub
+
+	@Override
+	void display() {
+		System.out.println("Teacher class");
+	}
+
+}