{"id":93,"date":"2009-01-31T21:20:11","date_gmt":"2009-02-01T04:20:11","guid":{"rendered":"http:\/\/www.connorgarvey.com\/blog\/?p=93"},"modified":"2010-02-19T13:21:43","modified_gmt":"2010-02-19T20:21:43","slug":"android-button-tutorial","status":"publish","type":"post","link":"https:\/\/connorgarvey.com\/blog\/?p=93","title":{"rendered":"Android button tutorial"},"content":{"rendered":"

A lot of people have found this site by searching for an Android button tutorial, so here it is.<\/p>\n

    \n
  1. This tutorial assumes that you already have an activity and are using an XML layout.<\/li>\n
  2. Open the layout XML and add the button element.\u00a0 Assign an ID with the “@+id” operator.\u00a0 The + tells Android to generate an ID for this element so that you can reference it in your Java files.\n
      \n
    1. This is an example. Your layout and text elements will probably be very different. In this example case, the ID of the button is “close”.\n
      <Button android:id=\"@+id\/close\"\r\n    android:layout_width=\"fill_parent\"\r\n    android:layout_height=\"wrap_content\"\r\n    android:layout_alignParentBottom=\"true\"\r\n    android:text=\"@string\/title_close\" \/><\/pre>\n<\/li>\n<\/ol>\n<\/li>\n
    2. Open the activity class.\u00a0 Add a class property to hold a reference to the button.
      <\/a>Code block<\/a><\/td><\/a> <\/a> <\/a> <\/td><\/tr><\/table><\/div>
      private<\/span> Button<\/span><\/a> closeButton;<\/span><\/pre><\/div><\/div><\/li>\n
    3. If you haven’t already, override the onCreate method.
      <\/a>Code block<\/a><\/td><\/a> <\/a> <\/a> <\/td><\/tr><\/table><\/div>
      @Override\nprotected<\/span> void<\/span> onCreate(<\/span>Bundle savedInstanceState)<\/span> {<\/span>\n}<\/span><\/pre><\/div><\/div><\/p>\n
        \n
      1. For this example, we don’t need the saved instance state, so ignore it.<\/li>\n<\/ol>\n<\/li>\n
      2. Now, in the onCreate method, attach a listener to the click event for the button.\u00a0 This example will call “finish()” on the activity, the Android analog of clicking the close button on a window.<\/li>\n<\/ol>\n
        <\/a>Code block<\/a><\/td><\/a> <\/a> <\/a> <\/td><\/tr><\/table><\/div>
        protected<\/span> void<\/span> onCreate(<\/span>Bundle savedInstanceState)<\/span> {<\/span>\n  this<\/span>.setContentView<\/span>(<\/span>R.layout<\/span>.layoutxml<\/span>)<\/span>;<\/span>\n  this<\/span>.closeButton<\/span> =<\/span> (<\/span>Button<\/span><\/a>)<\/span>this<\/span>.findViewById<\/span>(<\/span>R.id<\/span>.close<\/span>)<\/span>;<\/span>\n  this<\/span>.closeButton<\/span>.setOnClickListener<\/span>(<\/span>new<\/span> OnClickListener(<\/span>)<\/span> {<\/span>\n    @Override\n    public<\/span> void<\/span> onClick(<\/span>View<\/span><\/a> v)<\/span> {<\/span>\n      finish(<\/span>)<\/span>;<\/span>\n    }<\/span>\n  }<\/span>)<\/span>;<\/span>\n}<\/span><\/pre><\/div><\/div>\n
          \n
        1. Here’s a short description of what’s happening.\n
            \n
          1. First, get the button ID.\u00a0 The ID created earlier in the layout, “close”, is compiled by Android and assigned a unique integer ID which is available to the application through the “R” class, which I assume is short for “Resources”.<\/li>\n
          2. Request a reference to the button from the activity by calling “findViewById”.\u00a0 The button has to be retrieved from the activity because while an ID is unique in an activity, it is not unique among all activities.<\/li>\n
          3. Assign the retrieved button to an instance variable so that if you need it later, you can easily find it without having to query for it again.<\/li>\n
          4. Create a class implementing “OnClickListener” and set it as the on click listener for the button.<\/li>\n<\/ol>\n<\/li>\n<\/ol>\n
            As UI elements go, buttons are some of the simplest.\u00a0 Later, I’ll write about menus and dialogs, which aren’t so easy.<\/p>\n","protected":false},"excerpt":{"rendered":"
            Creating buttons in Android and assigning code to execute when they’re clicked is pretty straightforward if you know how to do it.  Insert the button into a layout, get a reference to it from the activity and assign a click listener and you have a working button.  This article describes the process in detail with example code.<\/p>\n","protected":false},"author":2,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_monsterinsights_skip_tracking":false,"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":"","jetpack_publicize_message":"","jetpack_publicize_feature_enabled":true,"jetpack_social_post_already_shared":false,"jetpack_social_options":{"image_generator_settings":{"template":"highway","enabled":false},"version":2}},"categories":[57],"tags":[3,10,4,8,7],"class_list":["post-93","post","type-post","status-publish","format-standard","hentry","category-android","tag-android","tag-button","tag-java","tag-mobile","tag-redpoint"],"jetpack_publicize_connections":[],"jetpack_featured_media_url":"","jetpack_shortlink":"https:\/\/wp.me\/p1ql2n-1v","jetpack_sharing_enabled":true,"_links":{"self":[{"href":"https:\/\/connorgarvey.com\/blog\/index.php?rest_route=\/wp\/v2\/posts\/93","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/connorgarvey.com\/blog\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/connorgarvey.com\/blog\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/connorgarvey.com\/blog\/index.php?rest_route=\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/connorgarvey.com\/blog\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=93"}],"version-history":[{"count":10,"href":"https:\/\/connorgarvey.com\/blog\/index.php?rest_route=\/wp\/v2\/posts\/93\/revisions"}],"predecessor-version":[{"id":96,"href":"https:\/\/connorgarvey.com\/blog\/index.php?rest_route=\/wp\/v2\/posts\/93\/revisions\/96"}],"wp:attachment":[{"href":"https:\/\/connorgarvey.com\/blog\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=93"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/connorgarvey.com\/blog\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=93"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/connorgarvey.com\/blog\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=93"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}