{"id":7476,"date":"2022-09-08T23:30:59","date_gmt":"2022-09-08T18:00:59","guid":{"rendered":"https:\/\/jassweb.com\/solved\/solved-why-when-i-uncommenting-tostring-it-writes-null\/"},"modified":"2022-09-08T23:30:59","modified_gmt":"2022-09-08T18:00:59","slug":"solved-why-when-i-uncommenting-tostring-it-writes-null","status":"publish","type":"post","link":"https:\/\/jassweb.com\/solved\/solved-why-when-i-uncommenting-tostring-it-writes-null\/","title":{"rendered":"[Solved] Why when I uncommenting toString it writes null?"},"content":{"rendered":"<p> [ad_1]<br \/>\n<\/p>\n<div id=\"answer-8989545\" class=\"answer js-answer accepted-answer js-accepted-answer\" data-answerid=\"8989545\" data-parentid=\"8989302\" data-score=\"2\" data-position-on-page=\"2\" data-highest-scored=\"0\" data-question-has-accepted-highest-score=\"0\" itemprop=\"suggestedAnswer\" itemscope itemtype=\"https:\/\/schema.org\/Answer\">\n<div class=\"post-layout\">\n<div class=\"votecell post-layout--left\"><\/div>\n<div class=\"answercell post-layout--right\">\n<div class=\"s-prose js-post-body\" itemprop=\"text\">\n<p>The reason is name and id are null.<\/p>\n<p>When you retrieve <code>this.id<\/code>, it returns the value of this classes (ProductEntry) member variable rather than its super class (which is what you want in this case).  If these member variables weren&#8217;t defined in ProductEntry, a call to this.id would retrieve the id from the super class, in this case Entry.  This is known as <a rel=\"nofollow noopener\" target=\"_blank\" href=\"http:\/\/en.wikipedia.org\/wiki\/Variable_shadowing\">Variable shadowing<\/a><\/p>\n<p>You can solve the problem in two possible ways.  The first is to simply remove name and id member variables from the sub classes of Entry.  This will mean <code>this.id<\/code> will access the member variable of <code>Entry<\/code> rather than its sub class <code>ProductEntry<\/code>.  The other option is to simply assign these in the constructor, but as you already storing these values in the super class, I don&#8217;t think this is the best approach.<\/p>\n<p>In the spirit of encapsulation you also may want to consider making your member variables private (only accessible by the class there defined in), or protected (accessible by the class its defined in and its sub types).<\/p>\n<\/p><\/div>\n<div class=\"mt24\"><\/div>\n<\/div>\n<p>            <span class=\"d-none\" itemprop=\"commentCount\"><\/span> <\/p><\/div>\n<\/div>\n<p>[ad_2]<\/p>\n<p>solved Why when I uncommenting toString it writes null? <\/p>\n","protected":false},"excerpt":{"rendered":"<p>[ad_1] The reason is name and id are null. When you retrieve this.id, it returns the value of this classes (ProductEntry) member variable rather than its super class (which is what you want in this case). If these member variables weren&#8217;t defined in ProductEntry, a call to this.id would retrieve the id from the super &#8230; <a title=\"[Solved] Why when I uncommenting toString it writes null?\" class=\"read-more\" href=\"https:\/\/jassweb.com\/solved\/solved-why-when-i-uncommenting-tostring-it-writes-null\/\" aria-label=\"More on [Solved] Why when I uncommenting toString it writes null?\">Read more<\/a><\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[320],"tags":[323],"class_list":["post-7476","post","type-post","status-publish","format-standard","hentry","category-solved","tag-java"],"yoast_head":"<!-- This site is optimized with the Yoast SEO plugin v26.5 - https:\/\/yoast.com\/wordpress\/plugins\/seo\/ -->\n<title>[Solved] Why when I uncommenting toString it writes null? - JassWeb<\/title>\n<meta name=\"robots\" content=\"index, follow, max-snippet:-1, max-image-preview:large, max-video-preview:-1\" \/>\n<link rel=\"canonical\" href=\"https:\/\/jassweb.com\/solved\/solved-why-when-i-uncommenting-tostring-it-writes-null\/\" \/>\n<meta property=\"og:locale\" content=\"en_US\" \/>\n<meta property=\"og:type\" content=\"article\" \/>\n<meta property=\"og:title\" content=\"[Solved] Why when I uncommenting toString it writes null? - JassWeb\" \/>\n<meta property=\"og:description\" content=\"[ad_1] The reason is name and id are null. When you retrieve this.id, it returns the value of this classes (ProductEntry) member variable rather than its super class (which is what you want in this case). If these member variables weren&#8217;t defined in ProductEntry, a call to this.id would retrieve the id from the super ... Read more\" \/>\n<meta property=\"og:url\" content=\"https:\/\/jassweb.com\/solved\/solved-why-when-i-uncommenting-tostring-it-writes-null\/\" \/>\n<meta property=\"og:site_name\" content=\"JassWeb\" \/>\n<meta property=\"article:published_time\" content=\"2022-09-08T18:00:59+00:00\" \/>\n<meta name=\"author\" content=\"Kirat\" \/>\n<meta name=\"twitter:card\" content=\"summary_large_image\" \/>\n<meta name=\"twitter:label1\" content=\"Written by\" \/>\n\t<meta name=\"twitter:data1\" content=\"Kirat\" \/>\n\t<meta name=\"twitter:label2\" content=\"Est. reading time\" \/>\n\t<meta name=\"twitter:data2\" content=\"1 minute\" \/>\n<script type=\"application\/ld+json\" class=\"yoast-schema-graph\">{\"@context\":\"https:\/\/schema.org\",\"@graph\":[{\"@type\":\"Article\",\"@id\":\"https:\/\/jassweb.com\/solved\/solved-why-when-i-uncommenting-tostring-it-writes-null\/#article\",\"isPartOf\":{\"@id\":\"https:\/\/jassweb.com\/solved\/solved-why-when-i-uncommenting-tostring-it-writes-null\/\"},\"author\":{\"name\":\"Kirat\",\"@id\":\"https:\/\/jassweb.com\/solved\/#\/schema\/person\/65c9c7b7958150c0dc8371fa35dd7c31\"},\"headline\":\"[Solved] Why when I uncommenting toString it writes null?\",\"datePublished\":\"2022-09-08T18:00:59+00:00\",\"mainEntityOfPage\":{\"@id\":\"https:\/\/jassweb.com\/solved\/solved-why-when-i-uncommenting-tostring-it-writes-null\/\"},\"wordCount\":194,\"publisher\":{\"@id\":\"https:\/\/jassweb.com\/solved\/#organization\"},\"keywords\":[\"java\"],\"articleSection\":[\"Solved\"],\"inLanguage\":\"en-US\"},{\"@type\":\"WebPage\",\"@id\":\"https:\/\/jassweb.com\/solved\/solved-why-when-i-uncommenting-tostring-it-writes-null\/\",\"url\":\"https:\/\/jassweb.com\/solved\/solved-why-when-i-uncommenting-tostring-it-writes-null\/\",\"name\":\"[Solved] Why when I uncommenting toString it writes null? - JassWeb\",\"isPartOf\":{\"@id\":\"https:\/\/jassweb.com\/solved\/#website\"},\"datePublished\":\"2022-09-08T18:00:59+00:00\",\"breadcrumb\":{\"@id\":\"https:\/\/jassweb.com\/solved\/solved-why-when-i-uncommenting-tostring-it-writes-null\/#breadcrumb\"},\"inLanguage\":\"en-US\",\"potentialAction\":[{\"@type\":\"ReadAction\",\"target\":[\"https:\/\/jassweb.com\/solved\/solved-why-when-i-uncommenting-tostring-it-writes-null\/\"]}]},{\"@type\":\"BreadcrumbList\",\"@id\":\"https:\/\/jassweb.com\/solved\/solved-why-when-i-uncommenting-tostring-it-writes-null\/#breadcrumb\",\"itemListElement\":[{\"@type\":\"ListItem\",\"position\":1,\"name\":\"Home\",\"item\":\"https:\/\/jassweb.com\/solved\/\"},{\"@type\":\"ListItem\",\"position\":2,\"name\":\"[Solved] Why when I uncommenting toString it writes null?\"}]},{\"@type\":\"WebSite\",\"@id\":\"https:\/\/jassweb.com\/solved\/#website\",\"url\":\"https:\/\/jassweb.com\/solved\/\",\"name\":\"JassWeb\",\"description\":\"Build High-quality Websites\",\"publisher\":{\"@id\":\"https:\/\/jassweb.com\/solved\/#organization\"},\"potentialAction\":[{\"@type\":\"SearchAction\",\"target\":{\"@type\":\"EntryPoint\",\"urlTemplate\":\"https:\/\/jassweb.com\/solved\/?s={search_term_string}\"},\"query-input\":{\"@type\":\"PropertyValueSpecification\",\"valueRequired\":true,\"valueName\":\"search_term_string\"}}],\"inLanguage\":\"en-US\"},{\"@type\":\"Organization\",\"@id\":\"https:\/\/jassweb.com\/solved\/#organization\",\"name\":\"Jass Web\",\"url\":\"https:\/\/jassweb.com\/solved\/\",\"logo\":{\"@type\":\"ImageObject\",\"inLanguage\":\"en-US\",\"@id\":\"https:\/\/jassweb.com\/solved\/#\/schema\/logo\/image\/\",\"url\":\"https:\/\/jassweb.com\/wp-content\/uploads\/2021\/02\/jass-website-logo-1.png\",\"contentUrl\":\"https:\/\/jassweb.com\/wp-content\/uploads\/2021\/02\/jass-website-logo-1.png\",\"width\":693,\"height\":132,\"caption\":\"Jass Web\"},\"image\":{\"@id\":\"https:\/\/jassweb.com\/solved\/#\/schema\/logo\/image\/\"}},{\"@type\":\"Person\",\"@id\":\"https:\/\/jassweb.com\/solved\/#\/schema\/person\/65c9c7b7958150c0dc8371fa35dd7c31\",\"name\":\"Kirat\",\"image\":{\"@type\":\"ImageObject\",\"inLanguage\":\"en-US\",\"@id\":\"https:\/\/jassweb.com\/solved\/#\/schema\/person\/image\/\",\"url\":\"https:\/\/jassweb.com\/solved\/wp-content\/litespeed\/avatar\/1261af3c9451399fa1336d28b98ea3bb.jpg?ver=1776403586\",\"contentUrl\":\"https:\/\/jassweb.com\/solved\/wp-content\/litespeed\/avatar\/1261af3c9451399fa1336d28b98ea3bb.jpg?ver=1776403586\",\"caption\":\"Kirat\"},\"sameAs\":[\"http:\/\/jassweb.com\"],\"url\":\"https:\/\/jassweb.com\/solved\/author\/jaspritsinghghumangmail-com\/\"}]}<\/script>\n<!-- \/ Yoast SEO plugin. -->","yoast_head_json":{"title":"[Solved] Why when I uncommenting toString it writes null? - JassWeb","robots":{"index":"index","follow":"follow","max-snippet":"max-snippet:-1","max-image-preview":"max-image-preview:large","max-video-preview":"max-video-preview:-1"},"canonical":"https:\/\/jassweb.com\/solved\/solved-why-when-i-uncommenting-tostring-it-writes-null\/","og_locale":"en_US","og_type":"article","og_title":"[Solved] Why when I uncommenting toString it writes null? - JassWeb","og_description":"[ad_1] The reason is name and id are null. When you retrieve this.id, it returns the value of this classes (ProductEntry) member variable rather than its super class (which is what you want in this case). If these member variables weren&#8217;t defined in ProductEntry, a call to this.id would retrieve the id from the super ... Read more","og_url":"https:\/\/jassweb.com\/solved\/solved-why-when-i-uncommenting-tostring-it-writes-null\/","og_site_name":"JassWeb","article_published_time":"2022-09-08T18:00:59+00:00","author":"Kirat","twitter_card":"summary_large_image","twitter_misc":{"Written by":"Kirat","Est. reading time":"1 minute"},"schema":{"@context":"https:\/\/schema.org","@graph":[{"@type":"Article","@id":"https:\/\/jassweb.com\/solved\/solved-why-when-i-uncommenting-tostring-it-writes-null\/#article","isPartOf":{"@id":"https:\/\/jassweb.com\/solved\/solved-why-when-i-uncommenting-tostring-it-writes-null\/"},"author":{"name":"Kirat","@id":"https:\/\/jassweb.com\/solved\/#\/schema\/person\/65c9c7b7958150c0dc8371fa35dd7c31"},"headline":"[Solved] Why when I uncommenting toString it writes null?","datePublished":"2022-09-08T18:00:59+00:00","mainEntityOfPage":{"@id":"https:\/\/jassweb.com\/solved\/solved-why-when-i-uncommenting-tostring-it-writes-null\/"},"wordCount":194,"publisher":{"@id":"https:\/\/jassweb.com\/solved\/#organization"},"keywords":["java"],"articleSection":["Solved"],"inLanguage":"en-US"},{"@type":"WebPage","@id":"https:\/\/jassweb.com\/solved\/solved-why-when-i-uncommenting-tostring-it-writes-null\/","url":"https:\/\/jassweb.com\/solved\/solved-why-when-i-uncommenting-tostring-it-writes-null\/","name":"[Solved] Why when I uncommenting toString it writes null? - JassWeb","isPartOf":{"@id":"https:\/\/jassweb.com\/solved\/#website"},"datePublished":"2022-09-08T18:00:59+00:00","breadcrumb":{"@id":"https:\/\/jassweb.com\/solved\/solved-why-when-i-uncommenting-tostring-it-writes-null\/#breadcrumb"},"inLanguage":"en-US","potentialAction":[{"@type":"ReadAction","target":["https:\/\/jassweb.com\/solved\/solved-why-when-i-uncommenting-tostring-it-writes-null\/"]}]},{"@type":"BreadcrumbList","@id":"https:\/\/jassweb.com\/solved\/solved-why-when-i-uncommenting-tostring-it-writes-null\/#breadcrumb","itemListElement":[{"@type":"ListItem","position":1,"name":"Home","item":"https:\/\/jassweb.com\/solved\/"},{"@type":"ListItem","position":2,"name":"[Solved] Why when I uncommenting toString it writes null?"}]},{"@type":"WebSite","@id":"https:\/\/jassweb.com\/solved\/#website","url":"https:\/\/jassweb.com\/solved\/","name":"JassWeb","description":"Build High-quality Websites","publisher":{"@id":"https:\/\/jassweb.com\/solved\/#organization"},"potentialAction":[{"@type":"SearchAction","target":{"@type":"EntryPoint","urlTemplate":"https:\/\/jassweb.com\/solved\/?s={search_term_string}"},"query-input":{"@type":"PropertyValueSpecification","valueRequired":true,"valueName":"search_term_string"}}],"inLanguage":"en-US"},{"@type":"Organization","@id":"https:\/\/jassweb.com\/solved\/#organization","name":"Jass Web","url":"https:\/\/jassweb.com\/solved\/","logo":{"@type":"ImageObject","inLanguage":"en-US","@id":"https:\/\/jassweb.com\/solved\/#\/schema\/logo\/image\/","url":"https:\/\/jassweb.com\/wp-content\/uploads\/2021\/02\/jass-website-logo-1.png","contentUrl":"https:\/\/jassweb.com\/wp-content\/uploads\/2021\/02\/jass-website-logo-1.png","width":693,"height":132,"caption":"Jass Web"},"image":{"@id":"https:\/\/jassweb.com\/solved\/#\/schema\/logo\/image\/"}},{"@type":"Person","@id":"https:\/\/jassweb.com\/solved\/#\/schema\/person\/65c9c7b7958150c0dc8371fa35dd7c31","name":"Kirat","image":{"@type":"ImageObject","inLanguage":"en-US","@id":"https:\/\/jassweb.com\/solved\/#\/schema\/person\/image\/","url":"https:\/\/jassweb.com\/solved\/wp-content\/litespeed\/avatar\/1261af3c9451399fa1336d28b98ea3bb.jpg?ver=1776403586","contentUrl":"https:\/\/jassweb.com\/solved\/wp-content\/litespeed\/avatar\/1261af3c9451399fa1336d28b98ea3bb.jpg?ver=1776403586","caption":"Kirat"},"sameAs":["http:\/\/jassweb.com"],"url":"https:\/\/jassweb.com\/solved\/author\/jaspritsinghghumangmail-com\/"}]}},"_links":{"self":[{"href":"https:\/\/jassweb.com\/solved\/wp-json\/wp\/v2\/posts\/7476","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/jassweb.com\/solved\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/jassweb.com\/solved\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/jassweb.com\/solved\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/jassweb.com\/solved\/wp-json\/wp\/v2\/comments?post=7476"}],"version-history":[{"count":0,"href":"https:\/\/jassweb.com\/solved\/wp-json\/wp\/v2\/posts\/7476\/revisions"}],"wp:attachment":[{"href":"https:\/\/jassweb.com\/solved\/wp-json\/wp\/v2\/media?parent=7476"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/jassweb.com\/solved\/wp-json\/wp\/v2\/categories?post=7476"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/jassweb.com\/solved\/wp-json\/wp\/v2\/tags?post=7476"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}