{"id":8986,"date":"2020-03-24T00:46:23","date_gmt":"2020-03-23T19:16:23","guid":{"rendered":"https:\/\/java2blog.com\/?p=8986"},"modified":"2021-05-09T11:05:03","modified_gmt":"2021-05-09T05:35:03","slug":"list-string-java","status":"publish","type":"post","link":"https:\/\/java2blog.com\/list-string-java\/","title":{"rendered":"Initialize List of String in java"},"content":{"rendered":"<div id=\"toc_container\" class=\"toc_light_blue no_bullets\"><p class=\"toc_title\">Table of Contents<\/p><ul class=\"toc_list\"><li><a href=\"#Initialize_List_of_Strings_with_values\">Initialize List of Strings with values<\/a><ul><li><a href=\"#Arrays8217s_asList\">Arrays&#8217;s asList<\/a><\/li><li><a href=\"#Streamof_Java_8\">Stream.of (Java 8)<\/a><\/li><li><a href=\"#Listof_Java_9\">List.of (Java 9)<\/a><\/li><li><a href=\"#Using_ArrayList8217s_add_method\">Using ArrayList&#8217;s add method<\/a><\/li><li><a href=\"#Using_guava_library\">Using guava library<\/a><\/li><\/ul><\/li><\/ul><\/div>\n<p>In this post, we will see how to initialize List of String in java.<\/p>\n<p>Can you initialize List of String as below:<\/p>\n<pre class=\"lang:java decode:1 \" >\nList<String> list = new List<String>();\n<\/pre>\n<p><code>You can't<\/code> because List is an <a href=\"https:\/\/java2blog.com\/interface-in-java-with-example\/\" rel=\"noopener noreferrer\" target=\"_blank\">interface<\/a> and it can not be instantiated with <code>new List()<\/code>.<\/p>\n<p>You need to instantiate it with the class that implements the <code>List<\/code> interface.<\/p>\n<p>Here are the common <a href=\"https:\/\/java2blog.com\/collections-java\/\" rel=\"noopener noreferrer\" target=\"_blank\">java Collections<\/a> classes which implement List interface.<\/p>\n<pre class=\"lang:java decode:1 \" >\n\/\/ ArrayList\nList<String> list1 = new ArrayList<String>();\n\n\/\/ LinkedList\nList<String> list2 = new LinkedList<String>();\n\n\/\/ Vector\nList<String> list3 = new Vector<String>();\n\n\/\/ CopyOnWriteArrayList\nList<String> list4 = new CopyOnWriteArrayList<String>();\n<\/pre>\n<p>In most of the cases, you will initialize List with ArrayList as below.<\/p>\n<pre class=\"lang:java decode:1 \" >\n\/\/ ArrayList\nList<String> list1 = new ArrayList<String>();\n<\/pre>\n<p>If you are using <code>java 7 or greater <\/code>than you can use diamond operator with <a href=\"https:\/\/java2blog.com\/java-generics-tutorial\/\" rel=\"noopener noreferrer\" target=\"_blank\">generics<\/a>.<\/p>\n<pre class=\"lang:java decode:1 \" >\n\/\/ ArrayList\nList<String> list1 = new ArrayList<>();\n<\/pre>\n<h2><span id=\"Initialize_List_of_Strings_with_values\">Initialize List of Strings with values<\/span><\/h2>\n<p>There are many ways to initialize list of Strings with values.<\/p>\n<h3><span id=\"Arrays8217s_asList\">Arrays&#8217;s asList<\/span><\/h3>\n<p>You can use Arrays&#8217;s asList method to initialize list with values.<\/p>\n<pre class=\"lang:java decode:1 \" >\nList<String> list1 = Arrays.asList(\"India\",\"China\",\"Bhutan\");\n<\/pre>\n<h3><span id=\"Streamof_Java_8\">Stream.of (Java 8)<\/span><\/h3>\n<p>You can use <a href=\"https:\/\/java2blog.com\/java-8-tutorial\/\" rel=\"noopener noreferrer\" target=\"_blank\">java 8<\/a>&#8216;s <a href=\"https:\/\/java2blog.com\/java-8-stream\/\" target=\"_blank\" rel=\"noopener noreferrer\">Stream<\/a> to initialize list of String with values.<\/p>\n<pre class=\"lang:java decode:1 \" >\nList<String> list1 = Stream.of(\"India\",\"China\",\"Bhutan\").collect(Collectors.toList());\n<\/pre>\n<h3><span id=\"Listof_Java_9\">List.of (Java 9)<\/span><\/h3>\n<p>Finally, java has introduced a <code>of()<\/code> method in List class to initialize list with values in java 9.<\/p>\n<pre class=\"lang:java decode:1 \" >\nList<String> list1 = List.of(\"India\",\"China\",\"Bhutan\");\n<\/pre>\n<h3><span id=\"Using_ArrayList8217s_add_method\">Using ArrayList&#8217;s add method<\/span><\/h3>\n<p>You can obviously initialize <a href=\"https:\/\/java2blog.com\/arraylist-in-java-with-example\/\" rel=\"noopener noreferrer\" target=\"_blank\">ArrayList<\/a> with new operator and then use add method to add element to the list.<\/p>\n<pre class=\"lang:java decode:1 \" >\n\/\/ ArrayList\nList<String> list1 = new ArrayList<>();\nlist1.add(\"India\");\nlist1.add(\"China\");\nlist1.add(\"Bhutan\");\n<\/pre>\n<h3><span id=\"Using_guava_library\"> Using guava library<\/span><\/h3>\n<p>You can use guava library as well.<\/p>\n<pre class=\"lang:java decode:1 \" >\nList<String> list1 = Lists.newArrayList(\"India\",\"China\",\"Bhutan\");\n<\/pre>\n<p>Here is the complete example.<\/p>\n<pre class=\"lang:java decode:1 \" >\npackage org.arpit.java2blog;\n\nimport java.util.ArrayList;\nimport java.util.Arrays;\nimport java.util.List;\nimport java.util.stream.Collectors;\nimport java.util.stream.Stream;\n\npublic class ListOfStringsMain {\n\n    public static void main(String[] args) {\n\n        List&lt;String&gt; list1 = new ArrayList&lt;&gt;();\n        list1.add(\"India\");\n        list1.add(\"China\");\n        list1.add(\"Bhutan\");\n        System.out.println(list1);\n\n        \/\/ Using Arrays.asList\n        List&lt;String&gt; list2= Arrays.asList(\"India\",\"China\",\"Bhutan\");\n        System.out.println(list2);\n\n        \/\/ Using Stream.of\n        List&lt;String&gt; list3 = Stream.of(\"India\",\"China\",\"Bhutan\").collect(Collectors.toList());\n        System.out.println(list3);\n\n        List&lt;String&gt; list4 = List.of(\"India\",\"China\",\"Bhutan\");\n        System.out.println(list4);\n    }\n}\n<\/pre>\n<p><strong>Output:<\/strong><\/p>\n<div class=\"content-box-green\">\n[India, China, Bhutan]\n[India, China, Bhutan]\n[India, China, Bhutan]\n[India, China, Bhutan]\n<\/div>\n<p>That&#8217;s all about how to initialize List of String in java.<\/p>\n","protected":false},"excerpt":{"rendered":"<p>Table of ContentsInitialize List of Strings with valuesArrays&#8217;s asListStream.of (Java 8)List.of (Java 9)Using ArrayList&#8217;s add methodUsing guava library In this post, we will see how to initialize List of String in java. Can you initialize List of String as below: List list = new List(); You can&#8217;t because List is an interface and it can [&hellip;]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"inline_featured_image":false,"_mi_skip_tracking":false},"categories":[27],"tags":[],"_links":{"self":[{"href":"https:\/\/java2blog.com\/wp-json\/wp\/v2\/posts\/8986"}],"collection":[{"href":"https:\/\/java2blog.com\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/java2blog.com\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/java2blog.com\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/java2blog.com\/wp-json\/wp\/v2\/comments?post=8986"}],"version-history":[{"count":0,"href":"https:\/\/java2blog.com\/wp-json\/wp\/v2\/posts\/8986\/revisions"}],"wp:attachment":[{"href":"https:\/\/java2blog.com\/wp-json\/wp\/v2\/media?parent=8986"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/java2blog.com\/wp-json\/wp\/v2\/categories?post=8986"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/java2blog.com\/wp-json\/wp\/v2\/tags?post=8986"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}