/
ch30.html
519 lines (341 loc) · 31.2 KB
/
ch30.html
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
<!doctype html>
<html lang="en">
<head>
<meta http-equiv="x-ua-compatible" content="ie=edge">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<meta name="description" content="Study guide for the Oracle Certified Professional, Java SE 8 Programmer Exam ">
<title>Java 8 Programmer II Study Guide: Exam 1Z0-809</title>
<link href="css/code.css" rel="stylesheet" type="text/css" />
<link href="css/style.css" rel="stylesheet" type="text/css" />
<link href="https://netdna.bootstrapcdn.com/font-awesome/3.2.1/css/font-awesome.css" rel="stylesheet">
<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.2.2/jquery.min.js"></script>
<script src="js/common-sections.js"></script>
</head>
<body>
<div class="nav"></div>
<div class="header">
<div class="title-container">
<div class="chapter-title">
<h1><i class="chapter">Chapter THIRTY</i><br />
Localization</h1>
<p><br /></p>
<h3 style="text-align: center;"><i>Exam Objectives</i></h3>
<p style="text-align: center;"><i>Read and set the locale by using the Locale object.<br /></i><i>Create and read a Properties file.<br /></i><i>Build a resource bundle for each locale and load a resource bundle in an application.</i></p>
</div>
</div>
</div>
<div class="container">
<div class="column">
<h2>Localization</h2>
<p><i>Localization</i> (abbreviated as l10N because of the number of characters between the first and the last letter) is the mechanism by which an application is adapted to a specific language and region.</p>
<p>It's related to the concept of <i>internationalization</i> (abbreviated as i18n for the same reason as localization), which is about designing an application that can handle different languages and regions.</p>
<p>The most common things that can be customized by language and/or region are messages, dates, and numbers.</p>
<p>In Java, it all starts with one class, <code>java.util.Locale</code>.</p>
<p>The <code>Locale</code> class basically represents a language and a country although, to be precise, a locale can have the following information:</p>
<ul>
<li>An ISO 639 alpha-2 or alpha-3 language code, like <i>ja</i> (Japanese)</li>
<li>An ISO 3166 alpha-2 country code or UN M.49 numeric-3 area code, like <i>JP</i> (Japan)</li>
<li>A variant name, usually empty but can be any string.</li>
<li>An ISO 15924 alpha-4 script code, like <i>Latn</i> (Latin)</li>
<li>A set of extensions represented by single characters, like <i>u</i>.</li>
</ul>
<p>But most of the time, we just work with languages and countries.</p>
<hr />
<h4><i>A Locale representation</i></h4>
<p><i>The language part is required</i></p>
<p><i>The country part is optional</i></p>
<p><i><code style="color:black;"><span style="font-size:600%"><b>fr_CA</b></span></code></i></p>
<p><i>Notice the lower case in the language part</i></p>
<p><i>Then the underscore for separation</i></p>
<p><i>Notice the upper case in the country part</i></p>
<hr />
<p>You can get the default locale of your machine with:</p>
<p><code class="java hljs">Locale locale = Locale.getDefault();</code></p>
<p>And get information like:</p>
<p><code class="java hljs">System.out.println(<span class="hljs-string">"Country Code: "</span><br />
+ locale.getCountry());<br />
System.out.println(<span class="hljs-string">"Country Name: "</span><br />
+ locale.getDisplayCountry());<br />
System.out.println(<span class="hljs-string">"Language Code: "</span><br />
+ locale.getLanguage());<br />
System.out.println(<span class="hljs-string">"Language Name: "</span><br />
+ locale.getDisplayLanguage());</code></p>
<p>The output (notice how the actual names are localized in Spanish):<br />
<code class="java hljs">Country Code: MX<br />
Country Name: México<br />
Language Code: es<br />
Language Name: español</code></p>
<p>You can also get all the locales supported by Java:</p>
<p><code class="java hljs">Locale [] locales = Locale.getAvailableLocales();<br />
Arrays.stream(locales)<br />
.forEach(System.out::println);</code></p>
<p>This would output around 160 locales in the form of <code>language[_country]</code>, for example:</p>
<p><code class="java hljs">it<br />
pt_BR<br />
ro_RO</code></p>
<h2>Setting the locale</h2>
<p>There are three different ways to create a <code>Locale</code> instance:</p>
<p><b>1. Using a constructor</b><br /> There are three constructors:</p>
<p><code class="java hljs">Locale(String language)<br />
Locale(String language, String country)<br />
Locale(String language, String country, String variant)</code></p>
<p>For example:</p>
<p><code class="java hljs">Locale chinese = <span class="hljs-keyword">new</span> Locale(<span class="hljs-string">"zh"</span>);<br />
Locale CHINA = <span class="hljs-keyword">new</span> Locale(<span class="hljs-string">"zh"</span>, <span class="hljs-string">"CN"</span>);</code></p>
<p><b>2. Using the forLanguageTag(String) factory method</b><br /> This method expects a language code, for example:</p>
<p><code class="java hljs">Locale german = Locale.forLanguageTag(<span class="hljs-string">"de"</span>);</code></p>
<p><b>3. Using Locale.Builder</b><br /> You can set the properties you need and build the object at the end, for example:</p>
<p><code class="java hljs">Locale japan = <span class="hljs-keyword">new</span> Locale.Builder()<br />
.setRegion(<span class="hljs-string">"JP"</span>)<br />
.setLanguage(<span class="hljs-string">"jp"</span>)<br />
.build();</code></p>
<p>Passing an invalid argument to any of the above three methods will not throw an exception, it will just create an object with invalid options that will make your program behave incorrectly:</p>
<p><code class="java hljs">Locale badLocale = <span class="hljs-keyword">new</span> Locale(<span class="hljs-string">"a"</span>, <span class="hljs-string">"A"</span>); <span class="hljs-comment">// No error</span><br />
System.out.println(badLocale); <span class="hljs-comment">// It prints a_A</span></code></p>
<p>So it's good to know that <code>Locale</code> class also provides predefined constants for some common languages and countries, for example:</p>
<p><code class="java hljs">Locale.GERMAN<br />
Locale.KOREAN<br />
Locale.UK<br />
Locale.ITALY</code></p>
<p>For the exam, you don't have to know all these constants, or some obscure language and country codes, just that there are four ways to start working with locales.</p>
<p>Once you have a <code>Locale</code> object, you can change the locale of your program with the <code>setDefault(Locale)</code> method:</p>
<p><code class="java hljs">System.out.println(Locale.getDefault()); <span class="hljs-comment">// Prints let's say en_GB</span><br />
Locale.setDefault(<span class="hljs-keyword">new</span> Locale(<span class="hljs-string">"en"</span>, <span class="hljs-string">"US"</span>));<br />
System.out.println(Locale.getDefault()); <span class="hljs-comment">// Now prints en_US</span></code></p>
<h2>Property files</h2>
<p>Property files define strings in key/value pairs separated by lines.</p>
<p>There are some rules, like:</p>
<ul>
<li>Spaces at the beginning of the line (if any) are ignored.</li>
<li>Any line that starts with <code>#</code> or <code>!</code> will be treated as a comment.</li>
<li>You can break a line for readability purposes with a backslash.</li>
</ul>
<p>For example, we can have the following file:</p>
<p><b>Messages.properties</b><br />
<code class="java hljs"># Video related messages<br />
video.added = The video has been added<br />
video.deleted = The video has been deleted</code></p>
<p>To read it, you create an instance of <code>java.util.Properties</code> and load it with either a <code>java.io.Reader</code> or a <code>java.io.InputStream</code>, for example:</p>
<p><code class="java hljs">Properties prop = <span class="hljs-keyword">new</span> Properties();<br />
<span class="hljs-keyword">try</span> (InputStream is = getClassLoader()<br />
.getResourceAsStream(<span class="hljs-string">"Messages.properties"</span>)) {<br />
prop.load(is); <span class="hljs-comment">// Load properties</span><br />
<span class="hljs-comment"> // Prints The video has been adde<br /></span><font color="#006A00"> </font>System.out.println(prop.getProperty(<span class="hljs-string">"video.added"</span>));<br />
<span class="hljs-comment"> // It prints a default value if the key is not foun<br /></span> System.out.println(prop.getProperty(<span class="hljs-string">"video.add"</span>, <span class="hljs-string">"default"</span>));<br />
<span class="hljs-comment"> // Get all properties keys</span><br />
Enumeration<?> e = prop.propertyNames();<br />
} <span class="hljs-keyword">catch</span> (IOException e) {<br />
e.printStackTrace();<br />
}</code></p>
<h2>Resource Bundles</h2>
<p>To localize an application, we have Resource Bundles, which define a set of keys with localized values. Resource Bundles can be property files or classes.</p>
<p>To support this, we have an abstract class <code>java.util.ResourceBundle</code> with two subclasses:</p>
<p><b>java.util.PropertyResourceBundle</b><br /> Each locale is represented by a property file. Keys and values are of type <code>String</code>.</p>
<p><b>java.util.ListResourceBundle</b><br /> Each locale is represented by a subclass of this class that overrides the method <code>Object[][] getContents()</code>. The returned array represents the keys and values. Keys must be of type <code>String</code>, but values can be any object.</p>
<p>In both methods, the name (of the file or the class) follows a convention which allows Java to search for resource bundles and match them to their corresponding locales.</p>
<p>That name convention is:</p>
<p><i><code style="color:black;"><b style="font-size:160%">package.Bundle_language_country_variant</b></code></i></p>
<p>For example:</p>
<p><i><code style="color:black"><b style="font-size:160%">com.example.MyBundle_fr_FR</b></code></i></p>
<p>Only the resource bundle name is required (and the name of the package if it is not the default one).</p>
<p>For example, we can have bundles with the following names (assuming we're working with property files, although it's the same with classes):</p>
<p><code class="java hljs">MyBundle.properties<br />
MyBundle_en.properties<br />
MyBundle_en_NZ.properties<br />
MyBundle_en_US.properties</code></p>
<p>To determine which bundle belongs to a particular locale, Java tries to find the most specific bundle that matches the properties of the locale.</p>
<p>This means that:</p>
<p>1. Java first searches for a bundle whose name matches the complete locale:<br />
<code>package.bundle_language_country_variant</code></p>
<p>2. If it cannot find one, it drops the last component of the name and repeats the search:<br />
<code>package.bundle_language_country</code></p>
<p>3. If it cannot find one, again, it drops the last component of the name and repeats the search:<br />
<code>package.bundle_language</code></p>
<p>4. If still cannot find one, the last component is dropped again, leaving just the name of the bundle:<br />
<code>package.bundle</code></p>
<p>If nothing is found, a <code>MissingBundleException</code> is thrown.</p>
<p>If a class and a property file share the same name, Java gives priority to the class.</p>
<p>But there's another important point.</p>
<p>In your program, you can use the keys of the matching resource bundle and <b>ANY</b> of its <b>PARENTS</b>.</p>
<p>The parents of a resource bundle are the ones with the same name but fewer components. For example, the parents of <code>MyBundle_es_ES</code> are:</p>
<p><code class="java hljs">MyBundle_es<br />
MyBundle</code></p>
<p>For example, let's assume the default locale <code>en_US</code>, and that your program is using those and other property files, all in the default package, with the values:</p>
<p><code class="java hljs"><b>MyBundle_EN.properties</b><br />
s = buddy</code></p>
<p><code class="java hljs"><b>MyBundle_es_ES.properties</b><br />
s = tío</code></p>
<p><code class="java hljs"><b>MyBundle_es.properties</b><br />
s = amigo</code></p>
<p><code class="java hljs"><b>MyBundle.properties</b><br />
hi = Hola</code></p>
<p>We can create a resource bundle like this:</p>
<p><code class="java hljs"><span class="hljs-keyword">public</span> <span class="hljs-class"><span class="hljs-keyword">class</span> <span class="hljs-title">Test</span></span> {<br />
<span class="hljs-function"><span class="hljs-keyword"> public</span> <span class="hljs-keyword">static</span> <span class="hljs-keyword">void</span> <span class="hljs-title">main</span><span class="hljs-params">(String[] args)</span></span> {<br />
Locale spain = <span class="hljs-keyword">new</span> Locale(<span class="hljs-string">"es"</span>, <span class="hljs-string">"ES"</span>);<br />
Locale spanish = <span class="hljs-keyword">new</span> Locale(<span class="hljs-string">"es"</span>);<br />
ResourceBundle rb = ResourceBundle.getBundle(<span class="hljs-string">"MyBundle"</span>, spain);<br />
System.out.format(<span class="hljs-string">"%s %s\n"</span>,<br />
rb.getString(<span class="hljs-string">"hi"</span>), rb.getString(<span class="hljs-string">"s"</span>));<br />
rb = ResourceBundle.getBundle(<span class="hljs-string">"MyBundle"</span>, spanish);<br />
System.out.format(<span class="hljs-string">"%s %s\n"</span>,<br />
rb.getString(<span class="hljs-string">"hi"</span>), rb.getString(<span class="hljs-string">"s"</span>));<br />
}<br />
}</code></p>
<p>The output:</p>
<p><code class="java hljs">Hola tío<br />
Hola amigo</code></p>
<p>As you can see, each locale picks different values for key <code>s</code>, but they both use the same for <code>hi</code> since this key is defined in their parent.</p>
<p>If you don't specify a locale, the <code>ResourceBundle</code> class will use the default locale of your system:</p>
<p><code class="java hljs">ResourceBundle rb = ResourceBundle.getBundle(<span class="hljs-string">"MyBundle"</span>);<br />
System.out.format(<span class="hljs-string">"%s %s\n"</span>,<br />
rb.getString(<span class="hljs-string">"hi"</span>), rb.getString(<span class="hljs-string">"s"</span>));</code></p>
<p>Since we assume that the default locale is <code>en_US</code>, the output is:</p>
<p><code class="java hljs">Hola buddy</code></p>
<p>We can also get all the keys in a resource bundle with the method <code>keySet()</code>:</p>
<p><code class="java hljs">ResourceBundle rb =<br />
ResourceBundle.getBundle(<span class="hljs-string">"MyBundle"</span>, spain);<br />
Set<String> keys = rb.keySet();<br />
keys.stream()<br />
.forEach(key -><br />
System.out.format(<span class="hljs-string">"%s %s\n"</span>, key, rb.getString(key)));</code></p>
<p>The output (notice it also prints the parent key):</p>
<p><code class="java hljs">hi Hola<br />
s tío</code></p>
<p>If instead of using property files we were using classes, the program would look like this:</p>
<p><code class="java hljs"><span class="hljs-keyword">package</span> bundles;<br />
<span class="hljs-keyword">public</span> <span class="hljs-class"><span class="hljs-keyword">class</span> <span class="hljs-title">MyBundle_EN</span> <span class="hljs-keyword">extends</span> <span class="hljs-title">ListResourceBundle</span></span> {<br />
<span class="hljs-annotation"> @Override</span><br />
<span class="hljs-keyword"> protected</span> Object[][] getContents() {<br />
<span class="hljs-keyword"> return</span> <span class="hljs-keyword">new</span> Object[][] {<br />
{ <span class="hljs-string">"s"</span>, <span class="hljs-string">"buddy"</span> }<br />
};<br />
}<br />
}<br />
<span class="hljs-keyword"><br />
package</span> bundles;<br />
<span class="hljs-keyword">public</span> <span class="hljs-class"><span class="hljs-keyword">class</span> <span class="hljs-title">MyBundle_es_ES</span> <span class="hljs-keyword">extends</span> <span class="hljs-title">ListResourceBundle</span></span> {<br />
<span class="hljs-annotation"> @Override</span><br />
<span class="hljs-keyword"> protected</span> Object[][] getContents() {<br />
<span class="hljs-keyword"> return</span> <span class="hljs-keyword">new</span> Object[][] {<br />
{ <span class="hljs-string">"s"</span>, <span class="hljs-string">"tío"</span> }<br />
};<br />
}<br />
}<br />
<br />
<span class="hljs-keyword">package</span> bundles;<br />
<span class="hljs-keyword">public</span> <span class="hljs-class"><span class="hljs-keyword">class</span> <span class="hljs-title">MyBundle_es</span> <span class="hljs-keyword">extends</span> <span class="hljs-title">ListResourceBundle</span></span> {<br />
<span class="hljs-annotation"> @Override</span><br />
<span class="hljs-keyword"> protected</span> Object[][] getContents() {<br />
<span class="hljs-keyword"> return</span> <span class="hljs-keyword">new</span> Object[][] {<br />
{ <span class="hljs-string">"s"</span>, <span class="hljs-string">"amigo"</span> }<br />
};<br />
}<br />
}<br />
<br />
<span class="hljs-keyword">package</span> bundles;<br />
<span class="hljs-keyword">public</span> <span class="hljs-class"><span class="hljs-keyword">class</span> <span class="hljs-title">MyBundle</span> <span class="hljs-keyword">extends</span> <span class="hljs-title">ListResourceBundle</span></span> {<br />
<span class="hljs-annotation"> @Override</span><br />
<span class="hljs-keyword"> protected</span> Object[][] getContents() {<br />
<span class="hljs-keyword"> return</span> <span class="hljs-keyword">new</span> Object[][] {<br />
{ <span class="hljs-string">"hi"</span>, <span class="hljs-string">"Hola"</span> }<br />
};<br />
}<br />
}<br />
<span class="hljs-keyword"><br />
public</span> <span class="hljs-class"><span class="hljs-keyword">class</span> <span class="hljs-title">Test</span></span> {<br />
<span class="hljs-function"><span class="hljs-keyword"> public</span> <span class="hljs-keyword">static</span> <span class="hljs-keyword">void</span> <span class="hljs-title">main</span><span class="hljs-params">(String[] args)</span></span> {<br />
Locale spain = <span class="hljs-keyword">new</span> Locale(<span class="hljs-string">"es"</span>, <span class="hljs-string">"ES"</span>);<br />
Locale spanish = <span class="hljs-keyword">new</span> Locale(<span class="hljs-string">"es"</span>);<br />
<br />
ResourceBundle rb =<br />
ResourceBundle.getBundle(<span class="hljs-string">"bundles.MyBundle"</span>, spain);<br />
System.out.format(<span class="hljs-string">"%s %s\n"</span>,<br />
rb.getString(<span class="hljs-string">"hi"</span>), rb.getString(<span class="hljs-string">"s"</span>));<br />
<br />
rb = ResourceBundle.getBundle(<span class="hljs-string">"bundles.MyBundle"</span>, spanish);<br />
System.out.format(<span class="hljs-string">"%s %s\n"</span>,<br />
rb.getString(<span class="hljs-string">"hi"</span>), rb.getString(<span class="hljs-string">"s"</span>));<br />
}<br />
}</code></p>
<p>The only thing that changed in the <code>Test</code> class was the name of the bundle (we had to reference the package). This should not surprise you, after all, both <code>PropertyResourceBundle</code> and <code>ListResourceBundle</code> inherit from the same class.</p>
<p>Remember also, when using classes we can have values of types other than <code>String</code>, for example:</p>
<p><code class="java hljs"><span class="hljs-keyword">public</span> <span class="hljs-class"><span class="hljs-keyword">class</span> <span class="hljs-title">MyBundle</span> <span class="hljs-keyword">extends</span> <span class="hljs-title">ListResourceBundle</span></span> {<br />
<span class="hljs-annotation"> @Override<br /></span><span class="hljs-keyword"> protected</span> Object[][] getContents() {<br />
<span class="hljs-keyword">return</span> <span class="hljs-keyword">new</span> Object[][] {<br />
{ <span class="hljs-string">"hi"</span>, <span class="hljs-string">"Hola"</span> },<br />
{ <span class="hljs-string">"number"</span>, <span class="hljs-keyword">new</span> Integer(<span class="hljs-number">100</span>) }<br />
};<br />
}<br />
}</code></p>
<p>To get an object value, we use:</p>
<p><code class="java hljs">Integer num = (Integer)rb.getObject(<span class="hljs-string">"number"</span>);</code></p>
<p>Instead of <code>rb.getString(key)</code>. In fact, this method is just a shortcut to:</p>
<p><code class="java hljs">String val = (String)rb.getObject(<span class="hljs-string">"hi"</span>);</code></p>
<h2>Key Points</h2>
<ul>
<li><i>Localization</i> (abbreviated as l10N because of the number of characters between the first and the last letter) is the mechanism by which an application is adapted to a particular language and region.</li>
<li>The <code>java.util.Locale</code> class basically represents a language and a country, and is the starting point for localization in Java.</li>
<li>You can get the default locale of your machine with: <code class="java hljs">Locale locale = Locale.getDefault();</code></li>
<li>You can also get all the locales supported by Java: <code class="java hljs">Locale [] locales = Locale.getAvailableLocales();</code></li>
<li>You can create a <code>Locale</code> object using a constructor:<br />
<code class="java hljs">Locale(String language)<br />
Locale(String language, String country)<br />
Locale(String language, String country, String variant)</code></li>
<li>By using the <code>forLanguageTag(String)</code> factory method: <code class="java hljs">Locale german = Locale.forLanguageTag(<span class="hljs-string">"de"</span>);</code></li>
<li>By using <code>Locale.Builder</code>: <code class="java hljs">Locale japan = <span class="hljs-keyword">new</span> Locale.Builder() .setRegion(<span class="hljs-string">"JP"</span>) .setLanguage(<span class="hljs-string">"jp"</span>) .build();</code></li>
<li>By using predefined constants for some common languages and countries, for example: <code>Locale.GERMAN<br />
Locale.KOREAN</code></li>
<li>Once you have a <code>Locale</code> object, you can change the locale of your program with the <code>setDefault(Locale)</code> method: <code class="java hljs">Locale.setDefault(<span class="hljs-keyword">new</span> Locale(<span class="hljs-string">"en"</span>, <span class="hljs-string">"US"</span>));</code></li>
<li>Property files define strings in key/value pairs separated by lines.</li>
<li>To localize an application, we have Resource Bundles, which define a set of keys with localized values. Resource Bundles can be property files or classes.</li>
<li><b>java.util.PropertyResourceBundle</b>. Each locale is represented by a property file. Keys and values are of type String.</li>
<li><b>java.util.ListResourceBundle</b>. Each locale is represented by a subclass of it that overrides the method <code>Object[][] getContents()</code>. The returned array represents the keys and values. Keys must be of type <code>String</code>, but values can be any object.</li>
<li>To determine which bundle belongs to a particular locale, Java tries to find the most specific bundle that matches the properties of the locale.</li>
<li>If it cannot locate one, the last component of the name is dropped until it's just the name of the bundle.</li>
<li>If nothing is found, a <code>MissingBundleException</code> is thrown.</li>
<li>If a class and a property file share the same name, Java gives priority to the class.</li>
<li>You can use the keys of the matching resource bundle and <b>ANY</b> of its <b>PARENTS</b>. The parents of a resource bundle are the ones with the same name but fewer components.</li>
</ul>
<h2>Self Test</h2>
<p>1. Given:</p>
<p><code class="java hljs"><span class="hljs-keyword">public</span> <span class="hljs-class"><span class="hljs-keyword">class</span> <span class="hljs-title">Question_30_1</span></span> {<br />
<span class="hljs-function"><span class="hljs-keyword"> public</span> <span class="hljs-keyword">static</span> <span class="hljs-keyword">void</span> <span class="hljs-title">main</span><span class="hljs-params">(String[] args)</span></span> {<br />
Locale locale = <span class="hljs-keyword">new</span> Locale(<span class="hljs-string">""</span>, <span class="hljs-string">""</span>);<br />
ResourceBundle rb = ResourceBundle.getBundle(<span class="hljs-string">"Bundle1"</span>, locale);<br />
System.out.println(rb.getString(<span class="hljs-string">"key1"</span>));<br />
}<br />
}</code></p>
<p><code><b>Bundle1.properties</b><br />
key1 = Hi</code></p>
<p>What is the result?<br /> A. <code>Hi</code><br /> B. <code>null</code><br /> C. Compilation fails<br /> D. An exception occurs at runtime</p>
<p>2. Which of the following are valid ways to create a locale?<br /> A. <code>new Locale();</code><br /> B. <code>Locale.Builder().setLanguage("de");</code><br /> C. <code>new Locale.Builder().setRegion("DE").build();</code><br /> D. <code>Locale.forRegionTag("it");</code></p>
<p>3. Assuming a default locale <code>de_DE</code>, which of the following resource bundles will be loaded first with</p>
<p><code class="java hljs">ResourceBundle rb = ResourceBundle.getBundle(<span class="hljs-string">"MyBundle"</span>);</code></p>
<p>A. <code>MyBundle.class</code><br /> B. <code>MyBundle.properties</code><br /> C. <code>MyBundle_de.class</code><br /> D. <code>MyBundle_de.properties</code></p>
<p>4. Given:</p>
<p><code class="java hljs"><span class="hljs-keyword">public</span> <span class="hljs-class"><span class="hljs-keyword">class</span> <span class="hljs-title">Question_30_4</span></span> {<br />
<span class="hljs-function"><span class="hljs-keyword">public</span> <span class="hljs-keyword">static</span> <span class="hljs-keyword">void</span> <span class="hljs-title">main</span><span class="hljs-params">(String[] args)</span></span> {<br />
Locale locale = <span class="hljs-keyword">new</span> Locale(<span class="hljs-string">"en"</span>, <span class="hljs-string">"CA"</span>);<br />
System.out.println(locale.toLanguageTag());<br />
}<br />
}</code></p>
<p>What is the result?<br /> A. <code>en</code><br /> B. <code>en_CA</code><br /> C. <code>CA</code><br /> D. <code>CA_en</code></p>
<p>5. Which of the following are valid ways to get a value given its key from a property file resource bundle <code>rb</code>?<br /> A. <code>rb.getValue("key");</code><br /> B. <code>rb.getProperty("key");</code><br /> C. <code>rb.getObject("key");</code><br /> D. <code>rb.get("key");</code></p>
<div class="answers">
<a href="ch30a.html" target="_blank">Open answers page</a>
</div>
<div class="book-info"></div>
<div class="linkbox">
<div class="previous">
<a href="ch29.html">29. JDBC API</a>
</div>
<div class="next">
<a href="ch31.html">A1. From Java 6 to Java 8</a>
</div>
<div style="clear:both;"></div>
</div>
</div>
</div>
</body>
</html>