{"id":1870,"date":"2015-07-27T23:30:40","date_gmt":"2015-07-27T22:30:40","guid":{"rendered":"http:\/\/blog.davidkeen.com\/?p=1870"},"modified":"2025-10-23T10:20:01","modified_gmt":"2025-10-22T23:50:01","slug":"generating-random-mobile-numbers-with-java-8","status":"publish","type":"post","link":"https:\/\/davidkeen.com\/blog\/2015\/07\/generating-random-mobile-numbers-with-java-8\/","title":{"rendered":"Generating random mobile numbers with Java 8"},"content":{"rendered":"\n<p>In a <a href=\"http:\/\/blog.davidkeen.com\/2014\/09\/generating-random-mobile-numbers-with-scala\/\">previous post<\/a> I gave a way of generating random test mobile numbers (Ofcom approved!) using Scala iterators.<\/p>\n\n\n\n<p>Now that Java 8 gives us lambdas and streams I thought I would see what those generators might look like in Java.<\/p>\n\n\n\n<p>Here&#8217;s the mobile generator:<\/p>\n\n\n\n<div class=\"wp-block-kevinbatdorf-code-block-pro\" data-code-block-pro-font-family=\"Code-Pro-JetBrains-Mono\" style=\"font-size:.875rem;font-family:Code-Pro-JetBrains-Mono,ui-monospace,SFMono-Regular,Menlo,Monaco,Consolas,monospace;line-height:1.25rem;--cbp-tab-width:2;tab-size:var(--cbp-tab-width, 2)\"><span style=\"display:block;padding:16px 0 0 16px;margin-bottom:-1px;width:100%;text-align:left;background-color:#2e3440ff\"><svg xmlns=\"http:\/\/www.w3.org\/2000\/svg\" width=\"54\" height=\"14\" viewBox=\"0 0 54 14\"><g fill=\"none\" fill-rule=\"evenodd\" transform=\"translate(1 1)\"><circle cx=\"6\" cy=\"6\" r=\"6\" fill=\"#FF5F56\" stroke=\"#E0443E\" stroke-width=\".5\"><\/circle><circle cx=\"26\" cy=\"6\" r=\"6\" fill=\"#FFBD2E\" stroke=\"#DEA123\" stroke-width=\".5\"><\/circle><circle cx=\"46\" cy=\"6\" r=\"6\" fill=\"#27C93F\" stroke=\"#1AAB29\" stroke-width=\".5\"><\/circle><\/g><\/svg><\/span><span role=\"button\" tabindex=\"0\" style=\"color:#d8dee9ff;display:none\" aria-label=\"Copy\" class=\"code-block-pro-copy-button\"><pre class=\"code-block-pro-copy-button-pre\" aria-hidden=\"true\"><textarea class=\"code-block-pro-copy-button-textarea\" tabindex=\"-1\" aria-hidden=\"true\" readonly>Supplier&lt;String> mobileSupplier = () -> String.format(\"447700900%03d\", ThreadLocalRandom.current().nextInt(999));<\/textarea><\/pre><svg xmlns=\"http:\/\/www.w3.org\/2000\/svg\" style=\"width:24px;height:24px\" fill=\"none\" viewBox=\"0 0 24 24\" stroke=\"currentColor\" stroke-width=\"2\"><path class=\"with-check\" stroke-linecap=\"round\" stroke-linejoin=\"round\" d=\"M9 5H7a2 2 0 00-2 2v12a2 2 0 002 2h10a2 2 0 002-2V7a2 2 0 00-2-2h-2M9 5a2 2 0 002 2h2a2 2 0 002-2M9 5a2 2 0 012-2h2a2 2 0 012 2m-6 9l2 2 4-4\"><\/path><path class=\"without-check\" stroke-linecap=\"round\" stroke-linejoin=\"round\" d=\"M9 5H7a2 2 0 00-2 2v12a2 2 0 002 2h10a2 2 0 002-2V7a2 2 0 00-2-2h-2M9 5a2 2 0 002 2h2a2 2 0 002-2M9 5a2 2 0 012-2h2a2 2 0 012 2\"><\/path><\/svg><\/span><pre class=\"shiki nord\" style=\"background-color: #2e3440ff\" tabindex=\"0\"><code><span class=\"line\"><span style=\"color: #8FBCBB\">Supplier<\/span><span style=\"color: #ECEFF4\">&lt;<\/span><span style=\"color: #8FBCBB\">String<\/span><span style=\"color: #ECEFF4\">&gt;<\/span><span style=\"color: #D8DEE9FF\"> <\/span><span style=\"color: #D8DEE9\">mobileSupplier<\/span><span style=\"color: #D8DEE9FF\"> <\/span><span style=\"color: #81A1C1\">=<\/span><span style=\"color: #D8DEE9FF\"> <\/span><span style=\"color: #ECEFF4\">()<\/span><span style=\"color: #D8DEE9FF\"> <\/span><span style=\"color: #8FBCBB\">-&gt;<\/span><span style=\"color: #D8DEE9FF\"> <\/span><span style=\"color: #D8DEE9\">String<\/span><span style=\"color: #ECEFF4\">.<\/span><span style=\"color: #88C0D0\">format<\/span><span style=\"color: #ECEFF4\">(<\/span><span style=\"color: #ECEFF4\">&quot;<\/span><span style=\"color: #A3BE8C\">447700900%03d<\/span><span style=\"color: #ECEFF4\">&quot;<\/span><span style=\"color: #ECEFF4\">,<\/span><span style=\"color: #D8DEE9FF\"> <\/span><span style=\"color: #D8DEE9\">ThreadLocalRandom<\/span><span style=\"color: #ECEFF4\">.<\/span><span style=\"color: #88C0D0\">current<\/span><span style=\"color: #ECEFF4\">().<\/span><span style=\"color: #88C0D0\">nextInt<\/span><span style=\"color: #ECEFF4\">(<\/span><span style=\"color: #B48EAD\">999<\/span><span style=\"color: #ECEFF4\">))<\/span><span style=\"color: #81A1C1\">;<\/span><\/span><\/code><\/pre><\/div>\n\n\n\n<p>Nice, still a one-liner.<\/p>\n\n\n\n<p>Generating pseudo MAC addresses is a little bit more trouble. This supplier uses another nested stream to generate the random hex array.<\/p>\n\n\n\n<div class=\"wp-block-kevinbatdorf-code-block-pro\" data-code-block-pro-font-family=\"Code-Pro-JetBrains-Mono\" style=\"font-size:.875rem;font-family:Code-Pro-JetBrains-Mono,ui-monospace,SFMono-Regular,Menlo,Monaco,Consolas,monospace;line-height:1.25rem;--cbp-tab-width:2;tab-size:var(--cbp-tab-width, 2)\"><span style=\"display:block;padding:16px 0 0 16px;margin-bottom:-1px;width:100%;text-align:left;background-color:#2e3440ff\"><svg xmlns=\"http:\/\/www.w3.org\/2000\/svg\" width=\"54\" height=\"14\" viewBox=\"0 0 54 14\"><g fill=\"none\" fill-rule=\"evenodd\" transform=\"translate(1 1)\"><circle cx=\"6\" cy=\"6\" r=\"6\" fill=\"#FF5F56\" stroke=\"#E0443E\" stroke-width=\".5\"><\/circle><circle cx=\"26\" cy=\"6\" r=\"6\" fill=\"#FFBD2E\" stroke=\"#DEA123\" stroke-width=\".5\"><\/circle><circle cx=\"46\" cy=\"6\" r=\"6\" fill=\"#27C93F\" stroke=\"#1AAB29\" stroke-width=\".5\"><\/circle><\/g><\/svg><\/span><span role=\"button\" tabindex=\"0\" style=\"color:#d8dee9ff;display:none\" aria-label=\"Copy\" class=\"code-block-pro-copy-button\"><pre class=\"code-block-pro-copy-button-pre\" aria-hidden=\"true\"><textarea class=\"code-block-pro-copy-button-textarea\" tabindex=\"-1\" aria-hidden=\"true\" readonly>Supplier&lt;String> macSupplier = () -> ThreadLocalRandom.current().ints(6, 0, 255)\n        .mapToObj(i -> String.format(\"%02x\", i))\n        .collect(Collectors.joining(\":\"));<\/textarea><\/pre><svg xmlns=\"http:\/\/www.w3.org\/2000\/svg\" style=\"width:24px;height:24px\" fill=\"none\" viewBox=\"0 0 24 24\" stroke=\"currentColor\" stroke-width=\"2\"><path class=\"with-check\" stroke-linecap=\"round\" stroke-linejoin=\"round\" d=\"M9 5H7a2 2 0 00-2 2v12a2 2 0 002 2h10a2 2 0 002-2V7a2 2 0 00-2-2h-2M9 5a2 2 0 002 2h2a2 2 0 002-2M9 5a2 2 0 012-2h2a2 2 0 012 2m-6 9l2 2 4-4\"><\/path><path class=\"without-check\" stroke-linecap=\"round\" stroke-linejoin=\"round\" d=\"M9 5H7a2 2 0 00-2 2v12a2 2 0 002 2h10a2 2 0 002-2V7a2 2 0 00-2-2h-2M9 5a2 2 0 002 2h2a2 2 0 002-2M9 5a2 2 0 012-2h2a2 2 0 012 2\"><\/path><\/svg><\/span><pre class=\"shiki nord\" style=\"background-color: #2e3440ff\" tabindex=\"0\"><code><span class=\"line\"><span style=\"color: #8FBCBB\">Supplier<\/span><span style=\"color: #ECEFF4\">&lt;<\/span><span style=\"color: #8FBCBB\">String<\/span><span style=\"color: #ECEFF4\">&gt;<\/span><span style=\"color: #D8DEE9FF\"> <\/span><span style=\"color: #D8DEE9\">macSupplier<\/span><span style=\"color: #D8DEE9FF\"> <\/span><span style=\"color: #81A1C1\">=<\/span><span style=\"color: #D8DEE9FF\"> <\/span><span style=\"color: #ECEFF4\">()<\/span><span style=\"color: #D8DEE9FF\"> <\/span><span style=\"color: #8FBCBB\">-&gt;<\/span><span style=\"color: #D8DEE9FF\"> <\/span><span style=\"color: #D8DEE9\">ThreadLocalRandom<\/span><span style=\"color: #ECEFF4\">.<\/span><span style=\"color: #88C0D0\">current<\/span><span style=\"color: #ECEFF4\">().<\/span><span style=\"color: #88C0D0\">ints<\/span><span style=\"color: #ECEFF4\">(<\/span><span style=\"color: #B48EAD\">6<\/span><span style=\"color: #ECEFF4\">,<\/span><span style=\"color: #D8DEE9FF\"> <\/span><span style=\"color: #B48EAD\">0<\/span><span style=\"color: #ECEFF4\">,<\/span><span style=\"color: #D8DEE9FF\"> <\/span><span style=\"color: #B48EAD\">255<\/span><span style=\"color: #ECEFF4\">)<\/span><\/span>\n<span class=\"line\"><span style=\"color: #D8DEE9FF\">        <\/span><span style=\"color: #ECEFF4\">.<\/span><span style=\"color: #88C0D0\">mapToObj<\/span><span style=\"color: #ECEFF4\">(<\/span><span style=\"color: #D8DEE9FF\">i <\/span><span style=\"color: #8FBCBB\">-&gt;<\/span><span style=\"color: #D8DEE9FF\"> <\/span><span style=\"color: #D8DEE9\">String<\/span><span style=\"color: #ECEFF4\">.<\/span><span style=\"color: #88C0D0\">format<\/span><span style=\"color: #ECEFF4\">(<\/span><span style=\"color: #ECEFF4\">&quot;<\/span><span style=\"color: #A3BE8C\">%02x<\/span><span style=\"color: #ECEFF4\">&quot;<\/span><span style=\"color: #ECEFF4\">,<\/span><span style=\"color: #D8DEE9FF\"> i<\/span><span style=\"color: #ECEFF4\">))<\/span><\/span>\n<span class=\"line\"><span style=\"color: #D8DEE9FF\">        <\/span><span style=\"color: #ECEFF4\">.<\/span><span style=\"color: #88C0D0\">collect<\/span><span style=\"color: #ECEFF4\">(<\/span><span style=\"color: #D8DEE9\">Collectors<\/span><span style=\"color: #ECEFF4\">.<\/span><span style=\"color: #88C0D0\">joining<\/span><span style=\"color: #ECEFF4\">(<\/span><span style=\"color: #ECEFF4\">&quot;<\/span><span style=\"color: #A3BE8C\">:<\/span><span style=\"color: #ECEFF4\">&quot;<\/span><span style=\"color: #ECEFF4\">))<\/span><span style=\"color: #81A1C1\">;<\/span><\/span><\/code><\/pre><\/div>\n\n\n\n<p>You use these <a href=\"https:\/\/docs.oracle.com\/javase\/8\/docs\/api\/java\/util\/function\/Supplier.html\">Supplier<\/a> functions with the static <a href=\"https:\/\/docs.oracle.com\/javase\/8\/docs\/api\/java\/util\/stream\/Stream.html#generate-java.util.function.Supplier-\">generate method of Stream<\/a>. Because the generators create infinite streams we use limit to just get a few values. Eg:<\/p>\n\n\n\n<div class=\"wp-block-kevinbatdorf-code-block-pro\" data-code-block-pro-font-family=\"Code-Pro-JetBrains-Mono\" style=\"font-size:.875rem;font-family:Code-Pro-JetBrains-Mono,ui-monospace,SFMono-Regular,Menlo,Monaco,Consolas,monospace;line-height:1.25rem;--cbp-tab-width:2;tab-size:var(--cbp-tab-width, 2)\"><span style=\"display:block;padding:16px 0 0 16px;margin-bottom:-1px;width:100%;text-align:left;background-color:#2e3440ff\"><svg xmlns=\"http:\/\/www.w3.org\/2000\/svg\" width=\"54\" height=\"14\" viewBox=\"0 0 54 14\"><g fill=\"none\" fill-rule=\"evenodd\" transform=\"translate(1 1)\"><circle cx=\"6\" cy=\"6\" r=\"6\" fill=\"#FF5F56\" stroke=\"#E0443E\" stroke-width=\".5\"><\/circle><circle cx=\"26\" cy=\"6\" r=\"6\" fill=\"#FFBD2E\" stroke=\"#DEA123\" stroke-width=\".5\"><\/circle><circle cx=\"46\" cy=\"6\" r=\"6\" fill=\"#27C93F\" stroke=\"#1AAB29\" stroke-width=\".5\"><\/circle><\/g><\/svg><\/span><span role=\"button\" tabindex=\"0\" style=\"color:#d8dee9ff;display:none\" aria-label=\"Copy\" class=\"code-block-pro-copy-button\"><pre class=\"code-block-pro-copy-button-pre\" aria-hidden=\"true\"><textarea class=\"code-block-pro-copy-button-textarea\" tabindex=\"-1\" aria-hidden=\"true\" readonly>import java.util.concurrent.ThreadLocalRandom;\nimport java.util.function.Supplier;\nimport java.util.stream.Collectors;\nimport java.util.stream.Stream;\n\npublic class Generators {\n\n    private static final Supplier&lt;String> mobileSupplier = () -> String.format(\"447700900%03d\", ThreadLocalRandom.current().nextInt(999));\n\n    private static final Supplier&lt;String> macSupplier = () -> ThreadLocalRandom.current().ints(6, 0, 255)\n            .mapToObj(i -> String.format(\"%02x\", i))\n            .collect(Collectors.joining(\":\"));\n\n    public static void main(String[] args) {\n        System.out.println(\"Some mobile numbers:\");\n        Stream.generate(Generators.mobileSupplier)\n                .limit(5)\n                .forEach(System.out::println);\n        System.out.println();\n\n        System.out.println(\"Some (pseudo) mac addresses:\");\n        Stream.generate(Generators.macSupplier)\n                .limit(5)\n                .forEach(System.out::println);\n    }\n}<\/textarea><\/pre><svg xmlns=\"http:\/\/www.w3.org\/2000\/svg\" style=\"width:24px;height:24px\" fill=\"none\" viewBox=\"0 0 24 24\" stroke=\"currentColor\" stroke-width=\"2\"><path class=\"with-check\" stroke-linecap=\"round\" stroke-linejoin=\"round\" d=\"M9 5H7a2 2 0 00-2 2v12a2 2 0 002 2h10a2 2 0 002-2V7a2 2 0 00-2-2h-2M9 5a2 2 0 002 2h2a2 2 0 002-2M9 5a2 2 0 012-2h2a2 2 0 012 2m-6 9l2 2 4-4\"><\/path><path class=\"without-check\" stroke-linecap=\"round\" stroke-linejoin=\"round\" d=\"M9 5H7a2 2 0 00-2 2v12a2 2 0 002 2h10a2 2 0 002-2V7a2 2 0 00-2-2h-2M9 5a2 2 0 002 2h2a2 2 0 002-2M9 5a2 2 0 012-2h2a2 2 0 012 2\"><\/path><\/svg><\/span><pre class=\"shiki nord\" style=\"background-color: #2e3440ff\" tabindex=\"0\"><code><span class=\"line\"><span style=\"color: #81A1C1\">import<\/span><span style=\"color: #D8DEE9FF\"> <\/span><span style=\"color: #8FBCBB\">java<\/span><span style=\"color: #ECEFF4\">.<\/span><span style=\"color: #8FBCBB\">util<\/span><span style=\"color: #ECEFF4\">.<\/span><span style=\"color: #8FBCBB\">concurrent<\/span><span style=\"color: #ECEFF4\">.<\/span><span style=\"color: #8FBCBB\">ThreadLocalRandom<\/span><span style=\"color: #81A1C1\">;<\/span><\/span>\n<span class=\"line\"><span style=\"color: #81A1C1\">import<\/span><span style=\"color: #D8DEE9FF\"> <\/span><span style=\"color: #8FBCBB\">java<\/span><span style=\"color: #ECEFF4\">.<\/span><span style=\"color: #8FBCBB\">util<\/span><span style=\"color: #ECEFF4\">.<\/span><span style=\"color: #8FBCBB\">function<\/span><span style=\"color: #ECEFF4\">.<\/span><span style=\"color: #8FBCBB\">Supplier<\/span><span style=\"color: #81A1C1\">;<\/span><\/span>\n<span class=\"line\"><span style=\"color: #81A1C1\">import<\/span><span style=\"color: #D8DEE9FF\"> <\/span><span style=\"color: #8FBCBB\">java<\/span><span style=\"color: #ECEFF4\">.<\/span><span style=\"color: #8FBCBB\">util<\/span><span style=\"color: #ECEFF4\">.<\/span><span style=\"color: #8FBCBB\">stream<\/span><span style=\"color: #ECEFF4\">.<\/span><span style=\"color: #8FBCBB\">Collectors<\/span><span style=\"color: #81A1C1\">;<\/span><\/span>\n<span class=\"line\"><span style=\"color: #81A1C1\">import<\/span><span style=\"color: #D8DEE9FF\"> <\/span><span style=\"color: #8FBCBB\">java<\/span><span style=\"color: #ECEFF4\">.<\/span><span style=\"color: #8FBCBB\">util<\/span><span style=\"color: #ECEFF4\">.<\/span><span style=\"color: #8FBCBB\">stream<\/span><span style=\"color: #ECEFF4\">.<\/span><span style=\"color: #8FBCBB\">Stream<\/span><span style=\"color: #81A1C1\">;<\/span><\/span>\n<span class=\"line\"><\/span>\n<span class=\"line\"><span style=\"color: #81A1C1\">public<\/span><span style=\"color: #D8DEE9FF\"> <\/span><span style=\"color: #81A1C1\">class<\/span><span style=\"color: #D8DEE9FF\"> <\/span><span style=\"color: #8FBCBB\">Generators<\/span><span style=\"color: #D8DEE9FF\"> <\/span><span style=\"color: #ECEFF4\">{<\/span><\/span>\n<span class=\"line\"><\/span>\n<span class=\"line\"><span style=\"color: #D8DEE9FF\">    <\/span><span style=\"color: #81A1C1\">private<\/span><span style=\"color: #D8DEE9FF\"> <\/span><span style=\"color: #81A1C1\">static<\/span><span style=\"color: #D8DEE9FF\"> <\/span><span style=\"color: #81A1C1\">final<\/span><span style=\"color: #D8DEE9FF\"> <\/span><span style=\"color: #8FBCBB\">Supplier<\/span><span style=\"color: #ECEFF4\">&lt;<\/span><span style=\"color: #8FBCBB\">String<\/span><span style=\"color: #ECEFF4\">&gt;<\/span><span style=\"color: #D8DEE9FF\"> <\/span><span style=\"color: #D8DEE9\">mobileSupplier<\/span><span style=\"color: #D8DEE9FF\"> <\/span><span style=\"color: #81A1C1\">=<\/span><span style=\"color: #D8DEE9FF\"> <\/span><span style=\"color: #ECEFF4\">()<\/span><span style=\"color: #D8DEE9FF\"> <\/span><span style=\"color: #8FBCBB\">-&gt;<\/span><span style=\"color: #D8DEE9FF\"> <\/span><span style=\"color: #D8DEE9\">String<\/span><span style=\"color: #ECEFF4\">.<\/span><span style=\"color: #88C0D0\">format<\/span><span style=\"color: #ECEFF4\">(<\/span><span style=\"color: #ECEFF4\">&quot;<\/span><span style=\"color: #A3BE8C\">447700900%03d<\/span><span style=\"color: #ECEFF4\">&quot;<\/span><span style=\"color: #ECEFF4\">,<\/span><span style=\"color: #D8DEE9FF\"> <\/span><span style=\"color: #D8DEE9\">ThreadLocalRandom<\/span><span style=\"color: #ECEFF4\">.<\/span><span style=\"color: #88C0D0\">current<\/span><span style=\"color: #ECEFF4\">().<\/span><span style=\"color: #88C0D0\">nextInt<\/span><span style=\"color: #ECEFF4\">(<\/span><span style=\"color: #B48EAD\">999<\/span><span style=\"color: #ECEFF4\">))<\/span><span style=\"color: #81A1C1\">;<\/span><\/span>\n<span class=\"line\"><\/span>\n<span class=\"line\"><span style=\"color: #D8DEE9FF\">    <\/span><span style=\"color: #81A1C1\">private<\/span><span style=\"color: #D8DEE9FF\"> <\/span><span style=\"color: #81A1C1\">static<\/span><span style=\"color: #D8DEE9FF\"> <\/span><span style=\"color: #81A1C1\">final<\/span><span style=\"color: #D8DEE9FF\"> <\/span><span style=\"color: #8FBCBB\">Supplier<\/span><span style=\"color: #ECEFF4\">&lt;<\/span><span style=\"color: #8FBCBB\">String<\/span><span style=\"color: #ECEFF4\">&gt;<\/span><span style=\"color: #D8DEE9FF\"> <\/span><span style=\"color: #D8DEE9\">macSupplier<\/span><span style=\"color: #D8DEE9FF\"> <\/span><span style=\"color: #81A1C1\">=<\/span><span style=\"color: #D8DEE9FF\"> <\/span><span style=\"color: #ECEFF4\">()<\/span><span style=\"color: #D8DEE9FF\"> <\/span><span style=\"color: #8FBCBB\">-&gt;<\/span><span style=\"color: #D8DEE9FF\"> <\/span><span style=\"color: #D8DEE9\">ThreadLocalRandom<\/span><span style=\"color: #ECEFF4\">.<\/span><span style=\"color: #88C0D0\">current<\/span><span style=\"color: #ECEFF4\">().<\/span><span style=\"color: #88C0D0\">ints<\/span><span style=\"color: #ECEFF4\">(<\/span><span style=\"color: #B48EAD\">6<\/span><span style=\"color: #ECEFF4\">,<\/span><span style=\"color: #D8DEE9FF\"> <\/span><span style=\"color: #B48EAD\">0<\/span><span style=\"color: #ECEFF4\">,<\/span><span style=\"color: #D8DEE9FF\"> <\/span><span style=\"color: #B48EAD\">255<\/span><span style=\"color: #ECEFF4\">)<\/span><\/span>\n<span class=\"line\"><span style=\"color: #D8DEE9FF\">            <\/span><span style=\"color: #ECEFF4\">.<\/span><span style=\"color: #88C0D0\">mapToObj<\/span><span style=\"color: #ECEFF4\">(<\/span><span style=\"color: #D8DEE9FF\">i <\/span><span style=\"color: #8FBCBB\">-&gt;<\/span><span style=\"color: #D8DEE9FF\"> <\/span><span style=\"color: #D8DEE9\">String<\/span><span style=\"color: #ECEFF4\">.<\/span><span style=\"color: #88C0D0\">format<\/span><span style=\"color: #ECEFF4\">(<\/span><span style=\"color: #ECEFF4\">&quot;<\/span><span style=\"color: #A3BE8C\">%02x<\/span><span style=\"color: #ECEFF4\">&quot;<\/span><span style=\"color: #ECEFF4\">,<\/span><span style=\"color: #D8DEE9FF\"> i<\/span><span style=\"color: #ECEFF4\">))<\/span><\/span>\n<span class=\"line\"><span style=\"color: #D8DEE9FF\">            <\/span><span style=\"color: #ECEFF4\">.<\/span><span style=\"color: #88C0D0\">collect<\/span><span style=\"color: #ECEFF4\">(<\/span><span style=\"color: #D8DEE9\">Collectors<\/span><span style=\"color: #ECEFF4\">.<\/span><span style=\"color: #88C0D0\">joining<\/span><span style=\"color: #ECEFF4\">(<\/span><span style=\"color: #ECEFF4\">&quot;<\/span><span style=\"color: #A3BE8C\">:<\/span><span style=\"color: #ECEFF4\">&quot;<\/span><span style=\"color: #ECEFF4\">))<\/span><span style=\"color: #81A1C1\">;<\/span><\/span>\n<span class=\"line\"><\/span>\n<span class=\"line\"><span style=\"color: #D8DEE9FF\">    <\/span><span style=\"color: #81A1C1\">public<\/span><span style=\"color: #D8DEE9FF\"> <\/span><span style=\"color: #81A1C1\">static<\/span><span style=\"color: #D8DEE9FF\"> <\/span><span style=\"color: #81A1C1\">void<\/span><span style=\"color: #D8DEE9FF\"> <\/span><span style=\"color: #88C0D0\">main<\/span><span style=\"color: #ECEFF4\">(<\/span><span style=\"color: #8FBCBB\">String<\/span><span style=\"color: #ECEFF4\">[]<\/span><span style=\"color: #D8DEE9FF\"> <\/span><span style=\"color: #D8DEE9\">args<\/span><span style=\"color: #ECEFF4\">)<\/span><span style=\"color: #D8DEE9FF\"> <\/span><span style=\"color: #ECEFF4\">{<\/span><\/span>\n<span class=\"line\"><span style=\"color: #D8DEE9FF\">        <\/span><span style=\"color: #D8DEE9\">System<\/span><span style=\"color: #ECEFF4\">.<\/span><span style=\"color: #D8DEE9\">out<\/span><span style=\"color: #ECEFF4\">.<\/span><span style=\"color: #88C0D0\">println<\/span><span style=\"color: #ECEFF4\">(<\/span><span style=\"color: #ECEFF4\">&quot;<\/span><span style=\"color: #A3BE8C\">Some mobile numbers:<\/span><span style=\"color: #ECEFF4\">&quot;<\/span><span style=\"color: #ECEFF4\">)<\/span><span style=\"color: #81A1C1\">;<\/span><\/span>\n<span class=\"line\"><span style=\"color: #D8DEE9FF\">        <\/span><span style=\"color: #D8DEE9\">Stream<\/span><span style=\"color: #ECEFF4\">.<\/span><span style=\"color: #88C0D0\">generate<\/span><span style=\"color: #ECEFF4\">(<\/span><span style=\"color: #D8DEE9\">Generators<\/span><span style=\"color: #ECEFF4\">.<\/span><span style=\"color: #D8DEE9\">mobileSupplier<\/span><span style=\"color: #ECEFF4\">)<\/span><\/span>\n<span class=\"line\"><span style=\"color: #D8DEE9FF\">                <\/span><span style=\"color: #ECEFF4\">.<\/span><span style=\"color: #88C0D0\">limit<\/span><span style=\"color: #ECEFF4\">(<\/span><span style=\"color: #B48EAD\">5<\/span><span style=\"color: #ECEFF4\">)<\/span><\/span>\n<span class=\"line\"><span style=\"color: #D8DEE9FF\">                <\/span><span style=\"color: #ECEFF4\">.<\/span><span style=\"color: #88C0D0\">forEach<\/span><span style=\"color: #ECEFF4\">(<\/span><span style=\"color: #D8DEE9\">System<\/span><span style=\"color: #ECEFF4\">.<\/span><span style=\"color: #D8DEE9\">out<\/span><span style=\"color: #81A1C1\">::<\/span><span style=\"color: #D8DEE9FF\">println<\/span><span style=\"color: #ECEFF4\">)<\/span><span style=\"color: #81A1C1\">;<\/span><\/span>\n<span class=\"line\"><span style=\"color: #D8DEE9FF\">        <\/span><span style=\"color: #D8DEE9\">System<\/span><span style=\"color: #ECEFF4\">.<\/span><span style=\"color: #D8DEE9\">out<\/span><span style=\"color: #ECEFF4\">.<\/span><span style=\"color: #88C0D0\">println<\/span><span style=\"color: #ECEFF4\">()<\/span><span style=\"color: #81A1C1\">;<\/span><\/span>\n<span class=\"line\"><\/span>\n<span class=\"line\"><span style=\"color: #D8DEE9FF\">        <\/span><span style=\"color: #D8DEE9\">System<\/span><span style=\"color: #ECEFF4\">.<\/span><span style=\"color: #D8DEE9\">out<\/span><span style=\"color: #ECEFF4\">.<\/span><span style=\"color: #88C0D0\">println<\/span><span style=\"color: #ECEFF4\">(<\/span><span style=\"color: #ECEFF4\">&quot;<\/span><span style=\"color: #A3BE8C\">Some (pseudo) mac addresses:<\/span><span style=\"color: #ECEFF4\">&quot;<\/span><span style=\"color: #ECEFF4\">)<\/span><span style=\"color: #81A1C1\">;<\/span><\/span>\n<span class=\"line\"><span style=\"color: #D8DEE9FF\">        <\/span><span style=\"color: #D8DEE9\">Stream<\/span><span style=\"color: #ECEFF4\">.<\/span><span style=\"color: #88C0D0\">generate<\/span><span style=\"color: #ECEFF4\">(<\/span><span style=\"color: #D8DEE9\">Generators<\/span><span style=\"color: #ECEFF4\">.<\/span><span style=\"color: #D8DEE9\">macSupplier<\/span><span style=\"color: #ECEFF4\">)<\/span><\/span>\n<span class=\"line\"><span style=\"color: #D8DEE9FF\">                <\/span><span style=\"color: #ECEFF4\">.<\/span><span style=\"color: #88C0D0\">limit<\/span><span style=\"color: #ECEFF4\">(<\/span><span style=\"color: #B48EAD\">5<\/span><span style=\"color: #ECEFF4\">)<\/span><\/span>\n<span class=\"line\"><span style=\"color: #D8DEE9FF\">                <\/span><span style=\"color: #ECEFF4\">.<\/span><span style=\"color: #88C0D0\">forEach<\/span><span style=\"color: #ECEFF4\">(<\/span><span style=\"color: #D8DEE9\">System<\/span><span style=\"color: #ECEFF4\">.<\/span><span style=\"color: #D8DEE9\">out<\/span><span style=\"color: #81A1C1\">::<\/span><span style=\"color: #D8DEE9FF\">println<\/span><span style=\"color: #ECEFF4\">)<\/span><span style=\"color: #81A1C1\">;<\/span><\/span>\n<span class=\"line\"><span style=\"color: #D8DEE9FF\">    <\/span><span style=\"color: #ECEFF4\">}<\/span><\/span>\n<span class=\"line\"><span style=\"color: #ECEFF4\">}<\/span><\/span><\/code><\/pre><\/div>\n\n\n\n<p>&nbsp;<\/p>\n","protected":false},"excerpt":{"rendered":"<p>Use Java 8&#8217;s lambdas and streams to generate random test data.<\/p>\n","protected":false},"author":1,"featured_media":2640,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"jetpack_post_was_ever_published":false,"_jetpack_newsletter_access":"","_jetpack_dont_email_post_to_subs":false,"_jetpack_newsletter_tier_id":0,"_jetpack_memberships_contains_paywalled_content":false,"_jetpack_memberships_contains_paid_content":false,"footnotes":""},"categories":[25],"tags":[],"class_list":["post-1870","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-dev"],"jetpack_featured_media_url":"https:\/\/i0.wp.com\/davidkeen.com\/blog\/wp-content\/uploads\/2015\/07\/roulette-roulette-wheel-ball-turn.jpg?fit=1280%2C853&ssl=1","jetpack_sharing_enabled":true,"_links":{"self":[{"href":"https:\/\/davidkeen.com\/blog\/wp-json\/wp\/v2\/posts\/1870","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/davidkeen.com\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/davidkeen.com\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/davidkeen.com\/blog\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/davidkeen.com\/blog\/wp-json\/wp\/v2\/comments?post=1870"}],"version-history":[{"count":15,"href":"https:\/\/davidkeen.com\/blog\/wp-json\/wp\/v2\/posts\/1870\/revisions"}],"predecessor-version":[{"id":2851,"href":"https:\/\/davidkeen.com\/blog\/wp-json\/wp\/v2\/posts\/1870\/revisions\/2851"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/davidkeen.com\/blog\/wp-json\/wp\/v2\/media\/2640"}],"wp:attachment":[{"href":"https:\/\/davidkeen.com\/blog\/wp-json\/wp\/v2\/media?parent=1870"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/davidkeen.com\/blog\/wp-json\/wp\/v2\/categories?post=1870"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/davidkeen.com\/blog\/wp-json\/wp\/v2\/tags?post=1870"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}