-
Notifications
You must be signed in to change notification settings - Fork 2
Expand file tree
/
Copy pathclass-objects-java.html
More file actions
619 lines (527 loc) · 32.7 KB
/
Copy pathclass-objects-java.html
File metadata and controls
619 lines (527 loc) · 32.7 KB
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8"/>
<meta name="viewport" content="width=device-width, initial-scale=1.0"/>
<meta name="description" content="Java is an object-oriented programming language. It is based on the concept of objects. A typical Java program creates many objects, which as you know, interact by invoking methods. An object consists of :"/>
<meta name="keywords" content="Java class,Java objects,class and objects,Java class and objects,classes in java,objects in java,about class,How to create class and objects,class and objects,what are classes,How to create objects of a class,C, C++, Python, Java, HTML, CSS, JavaScript, SQL, PHP, jQuery, XML, DOM, Bootstrap, Tutorials, Articles, Programming, training, learning, quiz, preferences, examples, code"/>
<title>Java Class and Objects | Java Tutorials | CodeMistic</title>
<!-- Google Tag Manager -->
<script>(function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':
new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],
j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src=
'https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);
})(window,document,'script','dataLayer','GTM-MCNC43J');</script>
<!-- End Google Tag Manager -->
<!-- Global site tag (gtag.js) - Google Analytics -->
<script async src="https://www.googletagmanager.com/gtag/js?id=G-YPTQSLH0XW"></script>
<script>
window.dataLayer = window.dataLayer || [];
function gtag(){dataLayer.push(arguments);}
gtag('js', new Date());
gtag('config', 'G-YPTQSLH0XW');
</script>
<script data-ad-client="ca-pub-5352867889640158" async src="https://pagead2.googlesyndication.com/pagead/js/adsbygoogle.js"></script>
<!-- Favicon -->
<link rel="icon" type="img/png" href="../favicon.png"/>
<!-- FONT AWESOME -->
<link rel="stylesheet" href="https://use.fontawesome.com/releases/v5.13.1/css/all.css"
integrity="sha384-xxzQGERXS00kBmZW/6qxqJPyxW3UR0BPsL4c8ILaIWXva5kFi7TxkIIaMiKtqV1Q" crossorigin="anonymous"/>
<!-- FONTS -->
<link href="https://fonts.googleapis.com/css2?family=Kalam:wght@700&family=Ubuntu&family=Varela+Round&display=swap"
rel="stylesheet"/>
<!-- Bootstrap -->
<link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/bootstrap/4.0.0/css/bootstrap.min.css" integrity=""
crossorigin="anonymous"/>
<link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/bootstrap/4.3.1/css/bootstrap.min.css" integrity=""
crossorigin="anonymous"/>
<!-- CSS -->
<link rel="stylesheet" href="../lang_styles.css"/>
</head>
<body>
<!-- Google Tag Manager (noscript) -->
<noscript><iframe src="https://www.googletagmanager.com/ns.html?id=GTM-MCNC43J"
height="0" width="0" style="display:none;visibility:hidden"></iframe></noscript>
<!-- End Google Tag Manager (noscript) -->
<!-- NAVIGATION BAR -->
<nav class="navbar fixed-top navbar-expand-xl navbar-dark">
<a class="navbar-brand" href="../index.html">CODEMISTIC</a>
<button class="navbar-toggler" type="button" data-toggle="collapse" data-target="#navbarSupportedContent" aria-controls="navbarSupportedContent" aria-expanded="false" aria-label="Toggle navigation">
<span class="navbar-toggler-icon"></span>
</button>
<div class="collapse navbar-collapse" id="navbarSupportedContent">
<ul class="navbar-nav ml-auto">
<li class="nav-item">
<a class="nav-link" href="../index.html">Home</a>
</li>
<li class="nav-item dropdown">
<a class="nav-link dropdown-toggle" href="#" id="navbarDropdown" role="button"
data-toggle="dropdown" aria-haspopup="true" aria-expanded="false">
Tutorials
</a>
<div class="dropdown-menu" aria-labelledby="navbarDropdown">
<a class="dropdown-item" href="../cpp.html">C++</a>
<div class="dropdown-divider"></div>
<a class="dropdown-item" href="../python.html">Python</a>
<div class="dropdown-divider"></div>
<a class="dropdown-item" href="../java.html">Java</a>
<div class="dropdown-divider"></div>
<a class="dropdown-item" href="../dsa.html">Data Structure and Algorithms</a>
<div class="dropdown-divider"></div>
<a class="dropdown-item" href="../tutorials.html">All Tutorials</a>
</div>
</li>
<li class="nav-item">
<a class="nav-link" href="../events.html">Events</a>
</li>
<li class="nav-item">
<a class="nav-link" href="../teen-code.html">Teen-Code</a>
</li>
<li class="nav-item">
<a class="nav-link" href="../campus.html">Campus Programme</a>
</li>
<!-- <li class="nav-item">
<a class="nav-link" href="https://docs.google.com/forms/d/e/1FAIpQLSc2O28YJpxQc6kh2tKpI_Lf5MwfwGXVnhMs0g5EEXobJ4Beeg/viewform?usp=sf_link" target="_blank">Contribute</a>
</li> -->
<li class="nav-item">
<a class="nav-link" href="../register.html">Join Our Community</a>
</li>
</ul>
</div>
</nav>
<!-- Accordion -->
<section class="lbar">
<div class="lang-img col-md-2">
<img src="../logo/java.png" alt="dsa" class="cpp-img">
</div>
<ul id="accordion" class="accordion ml-5">
<li>
<div class="link">Java Introduction<i class="fa fa-chevron-down"></i>
</div>
<ul class="submenu collapse ">
<li>
<a href="hello-world-java.html" class="closed" >Java Hello World</a>
</li>
<li>
<a href="JVM-JRE-JDK-java.html" class="closed">Java JVM, JRE and JDK</a>
</li>
<li>
<a href="data-types-java.html" class="closed">Java Data Types</a>
</li>
<li>
<a href="operators-java.html" class="closed">Java Operators</a>
</li>
<li>
<a href="input-and-output-java.html" class="closed">Java Input and Output</a>
</li>
<li>
<a href="expressions-and-blocks-java.html" class="closed">Java Expressions & Blocks</a>
</li>
<li>
<a href="comment-java.html" class="closed">Java Comment</a>
</li>
</ul>
</li>
<li>
<div class="link">Java Flow Control<i class="fa fa-chevron-down"></i>
</div>
<ul class="submenu collapse">
<li><a href="if-else-java.html" class="closed">Java if...else</a></li>
<li><a href="switch-statement-java.html" class="closed">Java switch Statement</a></li>
<li><a href="for-loop-java.html" class="closed">Java for Loop</a></li>
<li><a href="for-each-loop-java.html" class="closed">Java for-each Loop</a></li>
<li><a href="while-loop-java.html" class="closed">Java while Loop</a></li>
<li><a href="break-statement-java.html" class="closed">Java break Statement</a></li>
<li><a href="continue-statement-java.html" class="closed">Java continue Statement</a></li>
</ul>
</li>
<li>
<div class="link">Java Arrays<i class="fa fa-chevron-down"></i>
</div>
<ul class="submenu collapse">
<li><a href="arrays-java.html" class="closed" >Java Arrays</a></li>
<li><a href="multidimensional-array-java.html" class="closed">Multidimensional Array</a></li>
<li><a href="copy-arrays-java.html" class="closed" >Java Copy Arrays</a></li>
</ul>
</li>
<li>
<div class="link">Java OOP(I)<i class="fa fa-chevron-down"></i>
</div>
<ul class="submenu collapse show">
<li><a href="class-objects-java.html" class="opened"> Java Class and Objects</a></li>
<li><a href="methods-java.html" class="closed">Java Methods</a></li>
<li><a href="constructor-java.html" class="closed"> Java Constructor</a></li>
<li><a href="string-java.html" class="closed"> Java String</a></li>
<li><a href="access-modifiers-java.html" class="closed"> Java Access Modifiers</a></li>
<li><a href="this-keyword-java.html" class="closed"> Java this Keyword</a></li>
<li><a href="final-keyword-java.html" class="closed"> Java final Keyword</a></li>
<li><a href="recursion-java.html" class="closed"> Java Recursion</a></li>
<li><a href="instance-of-operator-java.html" class="closed"> Java instanceOf Operator</a></li>
</ul>
</li>
<li>
<div class="link">Java OOP(II)<i class="fa fa-chevron-down"></i>
</div>
<ul class="submenu collapse ">
<li><a href="inheritance-java.html" class="closed">Java Inheritance</a></li>
<li><a href="methods-overriding-java.html" class="closed">Java Methods Overriding </a></li>
<li><a href="super-keyword-java.html" class="closed">Java Super Keyword</a></li>
<li><a href="abstract-class-method-java.html" class="closed">Abstract Class ∓ Method</a></li>
<li><a href="interfaces-java.html" class="closed">Java Interfaces</a></li>
<li><a href="polymorphism-java.html" class="closed">Java Polymorphism</a></li>
<li><a href="encapsulation-java.html" class="closed">Java Encapsulation</a></li>
</ul>
</li>
<li>
<div class="link">Java OOP(III)<i class="fa fa-chevron-down"></i>
</div>
<ul class="submenu collapse">
<li><a href="nested-inner-class-java.html" class="closed">Nested & Inner Class</a></li>
<li><a href="static-class-java.html" class="closed">Java Static class </a></li>
<li><a href="anonymous-java.html" class="closed">Java Anonymous</a></li>
<li><a href="singleton-java.html" class="closed">Java Singleton</a></li>
<li><a href="enum-class-java.html" class="closed">Java enum Class </a></li>
<li><a href="enum-constructor-java.html" class="closed">Java enum Constructor</a></li>
<li><a href="enum-string-java.html" class="closed">Java enum String</a></li>
<li><a href="reflection-java.html" class="closed">Java Reflection</a></li>
</ul>
</li>
<li>
<div class="link">Java Exception Handling<i class="fa fa-chevron-down"></i>
</div>
<ul class="submenu collapse ">
<li><a href="exceptions-java.html" class="closed" >Java Exceptions</a>
</li>
<li><a href="exception-handling-java.html" class="closed" >Java Exception Handling</a>
</li>
<li> <a href="throw-throws-java.html" class="closed" >Java throw and throws</a>
</li>
<li><a href="catch-multiple-exceptions-java.html" class="closed" >Java catch Multiple Exceptions</a>
</li>
<li ><a href="try-with-resources-java.html" class="closed" >Java try-with-resources</a>
</li>
<li ><a href="annotation-java.html" class="closed" >Java Annotation</a>
</li>
<li><a href="logging-java.html" class="closed" >Java Logging</a>
</li>
<li><a href="assertions-java.html" class="closed" >Java Assertions</a>
</li>
</ul>
</li>
<li>
<div class="link">Java List<i class="fa fa-chevron-down"></i>
</div>
<ul class="submenu collapse">
<li><a href="collections-framework-java.html" class="closed" >Java Collections Framework</a></li>
<li><a href="collection-interface-java.html" class="closed" >Java Collection Interface</a></li>
<li><a href="list-interface-java.html" class="closed" >Java List Interface</a></li>
<li><a href="array-list-java.html" class="closed" >Java ArrayList</a ></li>
<li> <a href="vector-java.html" class="closed" >Java Vector</a></li>
<li> <a href="stack-java.html" class="closed" >Java Stack</a></li>
</ul>
</li>
<li>
<div class="link">Java Queue<i class="fa fa-chevron-down"></i>
</div>
<ul class="submenu collapse">
<li> <a href="queue-interface-java.html" class="closed">Java Queue Interface </a></li>
<li> <a href="priority-queue-java.html" class="closed">Java PriorityQueue </a></li>
<li> <a href="deque-interface-java.html" class="closed">Java Deque Interface </a></li>
<li> <a href="linked-list-java.html" class="closed">Java LinkedList </a></li>
<li> <a href="array-deque-java.html" class="closed">Java ArrayDeque </a></li>
<li> <a href="blocking-queue-interface-java.html"class="closed">Java BlockingQueue Interface </a></li>
<li> <a href="array-blocking-queue-java.html" class="closed">Java ArrayBlockingQueue </a></li>
<li> <a href="linked-blocking-queue-java.html" class="closed">Java LinkedBlockingQueue </a></li>
</ul>
</li>
<li>
<div class="link">Java Map<i class="fa fa-chevron-down"></i>
</div>
<ul class="submenu collapse">
<li><a href="map-interface-java.html" class="closed" >Java Map Interface</a> </li>
<li><a href="hashmap-java.html" class="closed" >Java HashMap</a> <li>
<li><a href="linked-hashmap-java.html" class="closed" >Java LinkedHashMap</a> <li>
<li><a href="weak-hashmap-java.html" class="closed" >Java WeakHashMap</a> <li>
<li><a href="enum-map-java.html" class="closed" >Java EnumMap</a> <li>
<li><a href="sorted-map-interface-java.html" class="closed" >Java SortedMap Interface</a> <li>
<li><a href="navigable-map-interface-java.html" class="closed" >Java NavigableMap Interface</a> <li>
<li><a href="tree-map-java.html" class="closed" >Java TreeMap</a> <li>
<li><a href="concurrent-map-interface-java.html" class="closed" >Java ConcurrentMap Interface</a> <li>
<li><a href="concurrent-hashmap-java.html" class="closed" >Java ConcurrentHashMap</a> <li>
</ul>
</li>
<li>
<div class="link">Java Set<i class="fa fa-chevron-down"></i>
</div>
<ul class="submenu collapse">
<li > <a href="set-interface-java.html" class="closed">Java Set Interface</a> </li>
<li><a href="hashset-java.html" class="closed">Java HashSet</a></li>
<li><a href="linked-hashset-java.html" class="closed">Java LinkedHashSet</a> </li>
<li><a href="enum-set-java.html" class="closed">Java EnumSet</a></li>
<li><a href="sorted-set-interface-java.html" class="closed">Java SortedSet Interface</a></li>
<li><a href="navigable-set-interface-java.html" class="closed">Java NavigableSet Interface</a></li>
<li><a href="tree-set-java.html" class="closed">Java TreeSet</a></li>
<li><a href="algorithms-java.html" class="closed">Java Algorithms</a></li>
<li><a href="iterator-java.html" class="closed">Java Iterator</a></li>
<li><a href="list-iterator-java.html" class="closed">Java ListIterator</a></li>
</ul>
</li>
<li>
<div class="link">Java I/O Streams<i class="fa fa-chevron-down"></i>
</div>
<ul class="submenu collapse">
<li > <a href="I/O-streams-java.html" class="closed">Java I/O Streams</a> </li>
<li><a href="input-stream-java.html" class="closed">Java Input Stream</a></li>
<li><a href="output-stream-java.html" class="closed">Java Output Stream</a> </li>
<li><a href="file-input-stream-java.html" class="closed">Java FileInput Stream</a></li>
<li><a href="file-output-stream-java.html" class="closed">Java FileOutput Stream</a></li>
<li><a href="bytearray-input-stream-java.html" class="closed">Java ByteArrayInput Stream</a></li>
<li><a href="bytearray-output-stream-java.html" class="closed">Java ByteArrayOutput Stream</a></li>
<li><a href="object-input-stream-java.html" class="closed">Java ObjectInput Stream</a></li>
<li><a href="object-output-stream-java.html" class="closed">Java ObjectOutput Stream</a></li>
<li><a href="buffered-input-java.html" class="closed">Java BufferedInput</a></li>
<li><a href="buffered-output-java.html" class="closed">Java BufferedOutput</a></li>
<li><a href="print-input-java.html" class="closed">Java PrintInput</a></li>
</ul>
</li>
<li>
<div class="link">Java Reader/Writer<i class="fa fa-chevron-down"></i>
</div>
<ul class="submenu collapse">
<li > <a href="reader-java.html" class="closed">Java Reader</a> </li>
<li><a href="writer-java.html" class="closed">Java Writer</a></li>
<li><a href="input-stream-reader-java.html" class="closed">Java InputStreamReader</a> </li>
<li><a href="output-stream-writer-java.html" class="closed">Java OutputStreamWriter</a></li>
<li><a href="file-reader-java.html" class="closed">Java FileReader</a></li>
<li><a href="file-writer-java.html" class="closed">Java FileWriter</a></li>
<li><a href="buffered-reader-java.html" class="closed">Java BufferedReader</a></li>
<li><a href="buffered-writer-java.html" class="closed">Java BufferedWriter</a></li>
<li><a href="string-reader-java.html" class="closed">Java StringReader</a></li>
<li><a href="string-writer-java.html" class="closed">Java StringWriter</a></li>
<li><a href="print-writer-java.html" class="closed">Java PrintWriter</a></li>
</ul>
</li>
<li>
<div class="link">Additional Topics<i class="fa fa-chevron-down"></i>
</div>
<ul class="submenu collapse">
<li > <a href="scanner-class-java.html" class="closed">Java Scanner Class</a> </li>
<li><a href="type-casting-java.html" class="closed">Java Type Casting</a></li>
<li><a href="autoboxing-and-unboxing-java.html" class="closed">Java Autoboxing and Unboxing</a> </li>
<li><a href="lambda-expression-java.html" class="closed">Java Lambda Expression</a></li>
<li><a href="generics-java.html" class="closed">Java Generics</a></li>
<li><a href="file-class-java.html" class="closed">Java File Class</a></li>
<li><a href="wrapper-class-java.html" class="closed">Java Wrapper Class</a></li>
<li><a href="command-line-arguments-java.html" class="closed">Java Command line Arguments</a></li>
</ul>
</li>
</ul>
</section>
<br>
<section class="para">
<!-- <div class="but mt-4">
<button class="btn btn-md btn-primary "><a href="../dsa.html"><i
class="fas fa-arrow-left "></i> Back to Index</a></button>
</div> -->
<!-- breadcrumb -->
<nav class="bdcrumb" id="bdcrumb" aria-label="breadcrumb">
<ul class="breadcrumb">
<li class="breadcrumb-item"><a href="../tutorials.html"><i class="fas fa-home"></i></a></li>
<li class="breadcrumb-item"><a href="../java.html#languages">Java Index</a></li>
<li class="breadcrumb-item active" aria-current="page">Java Class and Objects</li>
</ul>
</nav>
<!-- breadcrumb ending -->
<!-- para-->
<div class="wrapper">
<h3>Java Class and Objects</h3>
<h4>Introduction :</h4><p>In this tutorial, you will learn about object-oriented programming in Java and you will learn about Java classes and objects with the help of examples.</p>
<p>Java is an object-oriented programming language. It is based on the concept of objects. A typical Java program creates many objects, which as you know, interact by invoking methods. An object consists of :</p>
<ul><li><strong>State : </strong>It is represented by attributes of an object. It also reflects the properties of an object.</li>
<li><strong>Behavior : </strong>It is represented by methods of an object. It also reflects the response of an object with other objects.</li>
<li><strong>Identity : </strong>It gives a unique name to an object and enables one object to interact with other objects.</li></ul>
<h4>Example of an Object : Dog</h4>
<center>
<img alt="Java Object Example" src="javaphoto/Object_example.png" title="Java Object Example" width="454" height="300">
<figcaption><strong>fig: Java Object Example</strong></figcaption>
</center>
<h4>Principles of Object-oriented Programming:</h4>
<ul><li><a href="encapsulation-java.html">Encapsulation</a></li><li><a href="inheritance-java.html">Inheritance</a></li><li><a href="polymorphism-java.html">Polymorphism</a></li></ul>
<p>The focus of object-oriented programming is to break a complex programming task into objects that contain fields (to store data) and methods (to perform operations on fields).</p>
<hr>
<h3>Java Classes</h3>
<p>A class is a group of objects which have common properties. It is a template or blueprint from which objects are created. It is a logical entity. It can't be physical.</p>
<p>A class in Java can contain:</p>
<ul><li>Fields</li>
<li>Methods</li>
<li>Constructors</li>
<li>Blocks</li>
<li>Nested class and interface</li></ul>
<h4>Syntax to declare class in java : </h4>
<pre><code>
class <class_name>
{
//field
//method
}
</code></pre>
<h4>Example :</h4>
<pre><code>
public class Circle
{
private double x, y; // centre of the circle
private double r; // radius of circle
//Methods to return circumference and area
public double circumference()
{
return 2*3.14*r;
}
public double area()
{
return 3.14 * r * r;
}
}
<strong>Note : </strong>Here, we have created a class named Circle.
The class has three variables named x,y and r and two methods circumference() and area(). These variables and methods defined within a class are called members of the class.
</code></pre>
<p>
In the above example, we have used keywords private and public. These are known as access modifiers. To learn more, visit <a href="access-modifiers-java.html"> Java Access Modifiers</a>.</p>
<h3>Java Objects</h3>
<p>A typical Java program creates many objects, which as you know, interact by invoking methods. Through these object interactions, a program can carry out various tasks, such as implementing a GUI, running an animation, or sending and receiving information over a network. Once an object has completed the work for which it was created, its resources are recycled for use by other objects.</p>
<p>For example, suppose City is a class then Bhopal,Nagpur,Dhanbad and so on can be considered as objects of City class.</p>
<h4>Syntax to creating objects : </h4>
<pre><code>
className object = new className();
</code></pre>
<h4>Example :</h4>
<pre><code>
City bhopal= new City(); //1st object
City nagpur= new City(); //2nd object
<strong>Note : </strong>Objects are used to access members of a class.
</code></pre>
<h4>How to access members of a class ?</h4>
<p>Objects are used to access members of the class. We can access members (call methods and access instance variables) by using the "." operator. For example,</p>
<pre><code>
class City
{
checkPopulation()
{
//some code...
}
}
// create object
City bhopal = new City();
// access method checkPopulation
bhopal.checkPopulation(); //This statement calls the checkPopulation() method inside the City class for the <i>bhopal</i> object.
</code></pre>
<p>We have mentioned the word method quite a few times. You will learn about Java methods in detail in the next chapter. Here's what you need to know for now:
When you call the method using the above statement, all statements within the body of the checkPopulation() method is executed. Then, the control of the program jumps back to the statement following bhopal.checkPopulation();</p>
<h4>Example: Java Class and Objects</h4>
<pre><code>
//Java Program to illustrate how to define a class and fields
//Defining a Student class.
class Student
{
//defining fields
int id; //field or data member or instance variable
String name;
//creating main method inside the Student class
public void display(int id1, String name1)
{
System.out.println("id ="+id1+" and Name ="+name1);
}
public static void main(String args[])
{
//Creating an object or instance
Student s1=new Student(); //creating an object of Student
//Printing values of the object
s1.display(1,"CodeMistic");
}
}
</code></pre>
<strong>Output :</strong>
<pre><code>
id =1 and Name =CodeMistic
</code></pre>
<p>In the above program,</p>
<ol>
<li>We have created a class named <var>Student</var>.</li>
<li>The class has two instance variable <var>id</var> and <var>name</var> one method <code>display()</code> .</li>
<li>Inside the <var>Main</var> class, we have created one object <var>s1</var> of the <var>Student</var> class.</li>
<li>We then use the <var>s1</var> object to call <code>display()</code>.</li>
</ol>
<p><strong>Note</strong>: The variables defined inside a class are known as instance variables for a reason. When an object is created, it is called an instance of the class.</p>
<p>Each instance contains its own copy of the variables defined inside the class. Hence, known as instance variables.</p>
<hr>
</div>
<div class="but text-right">
<button class="btn btn-primary pull-right"><a href="methods-java.html">Next Topic <i
class="fas fa-arrow-right "></i><br/>Java Methods</a></button>
</div><br>
</section>
<!-- footer -->
<footer >
<div class="row footer" >
<div class="logo">
<img src="../image.png" alt="" class="f-img">
<h5>LEARN CODE DISCUSS</h5>
</div>
<div class="footer-column ">
<ul class="footer-ul">
<li class="foot-header"><strong>CodeMistic</strong></li>
<li class="f-li"><a href="../index.html" class="f-links">Home</a></li>
<li class="f-li"><a href="../team.html" class="f-links">Our Team</a></li>
<li class="f-li"><a href="../terms-and-conditions.html" class="f-links">Terms of Service</a></li>
<li class="f-li"><a href="../privacy-policy.html" class="f-links">Privacy Policy</a></li>
</ul>
</div>
<div class="footer-column ">
<ul class="footer-ul ">
<li class="foot-header"><strong>LEARN</strong></li>
<li class="f-li"><a href="../cpp.html" class="f-links">C++</a></li>
<li class="f-li"><a href="../java.html" class="f-links">Java</a></li>
<li class="f-li"><a href="../python.html" class="f-links">Python</a></li>
<li class="f-li"><a href="../dsa.html" class="f-links">DSA</a></li>
</ul>
</div>
<div class="footer-column ">
<ul class="footer-ul ">
<li class="foot-header"><strong>CONTRIBUTE</strong></li>
<li class="f-li"><a href="https://docs.google.com/forms/d/e/1FAIpQLSduxk_aP9M1lqUAebQJwRXiVm2ukmdgv3T7gjBpOsr_gdeOcQ/viewform?usp=sf_link" class="f-links" target="_blank">Write an Article/Blog</a></li>
<li class="f-li"><a href="https://docs.google.com/forms/d/e/1FAIpQLSc2O28YJpxQc6kh2tKpI_Lf5MwfwGXVnhMs0g5EEXobJ4Beeg/viewform?usp=sf_link" class="f-links" target="_blank">Internships</a></li>
<li class="f-li"><a href="https://docs.google.com/forms/d/e/1FAIpQLSe9nr_Aw0fGIqm3_xWhqEzTr3UWdOFz-pvKpQvkAsosORYq9w/viewform?usp=sf_link" class="f-links" target="_blank">Videos</a></li>
<li class="f-li"><a href="https://docs.google.com/forms/d/e/1FAIpQLScOW3hJjxxwzPYL4u51oboc4T1aDtIUEIRa20hKPKu4UlcZAA/viewform?usp=sf_link" class="f-links" target="_blank">Donations/Funds</a></li>
</ul>
</div>
</div>
<div class="footer-links" style="text-align: center;">
<!-- <h7>Connect With Us</h7><br><br> -->
<a href="https://www.facebook.com/codemistic " target="_blank "><i class="icons fa-2x fab fa-facebook "
style="color:#3b5998; "></i></a>
<a href="https://www.instagram.com/codemistic " target="_blank "><i class="icons fa-2x fab fa-instagram "
style="color:#e95950; "></i></a>
<a href="https://www.twitter.com/codemistic " target="_blank "><i class="icons fa-2x fab fa-twitter "
style="color:#8accf5; "></i></a>
<a href="https://www.linkedin.com/company/codemistic " target="_blank "><i
class="icons fa-2x fab fa-linkedin " style="color:#88b3ee; "></i></a>
<a href="https://t.me/codemistic " target="_blank "><i class="icons fa-2x fab fa-telegram "
style="color:#65adda; "></i></a>
<a href="https://www.youtube.com/channel/UCS1Iv_kkgQGDwoXtvrlwlag " target="_blank "><i
class="icons fa-2x fab fa-youtube " style="color:red; "></i></a>
<p class="foot mt-3">© Copyright : <strong>CodeMistic</strong> All Rights Reserved.</p>
</div>
</footer>
<!-- CSS Scripts -->
<script src="https://code.jquery.com/jquery-3.5.1.slim.min.js "
integrity="sha384-DfXdz2htPH0lsSSs5nCTpuj/zy4C+OGpamoFVy38MVBnE+IbbVYUew+OrCXaRkfj "
crossorigin="anonymous "></script>
<script src="https://cdn.jsdelivr.net/npm/popper.js@1.16.0/dist/umd/popper.min.js "
integrity="sha384-Q6E9RHvbIyZFJoft+2mJbHaEWldlvI9IOYy5n3zV9zzTtmI3UksdQRVvoxMfooAo "
crossorigin="anonymous "></script>
<script src="https://stackpath.bootstrapcdn.com/bootstrap/4.5.0/js/bootstrap.min.js "
integrity="sha384-OgVRvuATP1z7JjHLkuOU7Xw704+h835Lr+6QL9UvYjZE3Ipu6Tp75j7Bh/kR0JKI "
crossorigin="anonymous "></script>
<script src='https://cdnjs.cloudflare.com/ajax/libs/jquery/3.2.1/jquery.min.js'></script>
<script src='../side.js'></script>
</body>
</html>