package firstprogramjava;
class FirstProgram {
public static void main(String args[]){
System.out.println("Hellooooooooooo.......");
}
}
---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------package myfirstgui;
//Usually you will require both swing and awt packages
//even if you are working with just swings.
import javax.swing.*;
import java.awt.*;
class FirstGui{
public static void main(String args[]){
//Creating the Frame
JFrame frame = new JFrame("Chat Frame");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setSize(400,400);
//Creating the MenuBar and adding components
JMenuBar mb = new JMenuBar();
JMenu m1 = new JMenu("FILE");
JMenu m2 = new JMenu("Help");
mb.add(m1);
mb.add(m2);
JMenuItem m11 = new JMenuItem("Open");
JMenuItem m22 =new JMenuItem("Save as");
m1.add(m11);
m1.add(m22);
//Creating the panel at bottom and adding components
JPanel panel = new JPanel(); // the panel is not visible in output
JLabel label = new JLabel("Enter Text");
JTextField tf = new JTextField(10);// accepts upto 10 characters
JButton send = new JButton("Send");
JButton reset = new JButton("Reset");
panel.add(label);// Components Added using Flow Layout
panel.add(tf);
panel.add(send);
panel.add(reset);
//Text Area at the Center
JTextArea ta = new JTextArea();
//Adding Components to the frame.
frame.getContentPane().add(BorderLayout.SOUTH,panel);
frame.getContentPane().add(BorderLayout.NORTH,mb);
frame.getContentPane().add(BorderLayout.CENTER,ta);
frame.setVisible(true);
}
}
Output:-
class FirstProgram {
public static void main(String args[]){
System.out.println("Hellooooooooooo.......");
}
}
---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------package myfirstgui;
//Usually you will require both swing and awt packages
//even if you are working with just swings.
import javax.swing.*;
import java.awt.*;
class FirstGui{
public static void main(String args[]){
//Creating the Frame
JFrame frame = new JFrame("Chat Frame");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setSize(400,400);
//Creating the MenuBar and adding components
JMenuBar mb = new JMenuBar();
JMenu m1 = new JMenu("FILE");
JMenu m2 = new JMenu("Help");
mb.add(m1);
mb.add(m2);
JMenuItem m11 = new JMenuItem("Open");
JMenuItem m22 =new JMenuItem("Save as");
m1.add(m11);
m1.add(m22);
//Creating the panel at bottom and adding components
JPanel panel = new JPanel(); // the panel is not visible in output
JLabel label = new JLabel("Enter Text");
JTextField tf = new JTextField(10);// accepts upto 10 characters
JButton send = new JButton("Send");
JButton reset = new JButton("Reset");
panel.add(label);// Components Added using Flow Layout
panel.add(tf);
panel.add(send);
panel.add(reset);
//Text Area at the Center
JTextArea ta = new JTextArea();
//Adding Components to the frame.
frame.getContentPane().add(BorderLayout.SOUTH,panel);
frame.getContentPane().add(BorderLayout.NORTH,mb);
frame.getContentPane().add(BorderLayout.CENTER,ta);
frame.setVisible(true);
}
}
Output:-
---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Inheritance class Programme
package inheritclss;
public class InheritClassLesson{
public static void main(String args[]){
X x= new X();
Y y = new Y();
y.m2();
//x.m1();
//y.m1();
//x = y; parent pointing to object of child
//x.m1() ;
//y.a=10;
}
}
class X{
private int a;
int b;
public void m1(){
System.out.println("This is method m1 of class X");
}
}
class Y extends X{
int c;
//new instance variable of class Y
public void m1(){
//overriden method
System.out.println("This is method m1 of class Y");
}
public void m2(){
super.m1();
System.out.println("This is method m2 of class Y");
}
}
Output:-
---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
String
package firststring;
class StringClass{
public static void main(String []args){
String strTest = "100";
/*This statement results in a compilation error as you
cannot do arithmetic operation on Strings
System.out.println("Using String:" + (strTest/4));
Convert the String to Integer*/
int iTest = Integer.parseInt(strTest);
System.out.println("Actual String:"+ strTest);
System.out.println("Converted to Int:" + iTest);
System.out.println("Arithmetic Operation on Int:" + (iTest/5));
}
}
Output:-
---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Array:-
package firstjavaarray;
import java.util.ArrayList;
class FirstArray {
public static void main(String[] args) {
//Creating a generic ArrayList
ArrayList arlTest = new ArrayList();
//Size of arrayList
System.out.println("Size of ArrayList at creation: " + arlTest.size());
//Lets add some elements to it
arlTest.add("D");
arlTest.add("U");
arlTest.add("K");
arlTest.add("E");
//Recheck the size after adding elements
System.out.println("Size of ArrayList after adding elements: " + arlTest.size());
//Display all contents of ArrayList
System.out.println("List of all elements: " + arlTest);
//Remove some elements from the list
arlTest.remove("D");
System.out.println("See contents after removing one element: " + arlTest);
//Remove element by index
arlTest.remove(2);
System.out.println("See contents after removing element by index: " + arlTest);
//Check size after removing elements
System.out.println("Size of arrayList after removing elements: " + arlTest.size());
System.out.println("List of all elements after removing elements: " + arlTest);
//Check if the list contains "K"
System.out.println(arlTest.contains("K"));
}
}
Output:-
---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Loops:-
package loopspkg;
class LoopsClass {
public static void main(String[] args) {
String[] arrData = {"Alpha", "Beta", "Gamma", "Delta", "Sigma"};
System.out.println("Using conventional For Loop:");
for(int i=0; i< arrData.length; i++){
System.out.println(arrData[i]);
}
System.out.println("\nUsing Foreach loop:");
for (String strTemp : arrData){
System.out.println(strTemp);
}
}
}
---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Date format
package datepkg;
import java.text.SimpleDateFormat;
import java.util.Date;
class DateClass {
public static void main(String args[]) {
Date objDate = new Date( ); // Current System Date and time is assigned to objDate
System.out.println(objDate);
String strDateFormat = "hh:mm:ss a dd-MMM-yyyy";//Date format is Specified
SimpleDateFormat objSDF = new SimpleDateFormat (strDateFormat);//Date format string is passed as an argument to the Date format object
System.out.println(objSDF.format(objDate));//Date formatting is applied to the current date
}
}
Output:-
Single Thread
package singlethreadd;
public class SingleThreads implements Runnable
{
/**
* @param args
*/
public static void main(String[] args) {
Thread guruThread1 = new Thread("Guru1");
Thread guruThread2 = new Thread("Guru2");
guruThread1.start();
guruThread2.start();
System.out.println("Thread names are following:");
System.out.println(guruThread1.getName());
System.out.println(guruThread2.getName());
}
@Override
public void run() {
}
}
Output:-
Java multithreading example
In this example, we will learn about overriding methods run() and start() method of a runnable interface and create two threads of that class and run them accordingly.
Also, we are taking two classes,
- One which will implement the runnable interface and
- Other one which will have the main method and execute accordingly.
package multithreadingpkg;
public class MultiThreadingClass {
public static void main(String[] args) {
// TODO Auto-generated method stub
GuruThread3 threadguru1 = new GuruThread3("guru1");
threadguru1.start();
GuruThread3 threadguru2 = new GuruThread3("guru2");
threadguru2.start();}
}
class GuruThread3 implements Runnable
{ Thread guruthread;
private String guruname;
GuruThread3(String name)
{
guruname = name;
}
@Override
public void run() {
System.out.println("Thread running" +guruname);
for(int i=0;i<4;i++)
{
System.out.println(i);
System.out.println(guruname);
try {
Thread.sleep(1000);
} catch (InterruptedException e) {
System.out.println("Thread has been interrupted");
}
}
}
public void start()
{
System.out.println("Thread started");
if(guruthread==null)
{
guruthread = new Thread(this,guruname);
guruthread.start();
}
}
}
Output:-
