{"id":22,"date":"2019-01-14T21:55:11","date_gmt":"2019-01-14T21:55:11","guid":{"rendered":"https:\/\/kindsonthegenius.com\/java\/?p=22"},"modified":"2019-03-02T04:34:12","modified_gmt":"2019-03-02T04:34:12","slug":"04-java-keywords","status":"publish","type":"post","link":"https:\/\/kindsonthegenius.com\/java\/04-java-keywords\/","title":{"rendered":"Java – Keywords"},"content":{"rendered":"

In this tutorial, we would examine various Java keywords beginning with Java Modifiers<\/p>\n

We would cover the following.<\/p>\n

    \n
  1. Java Modifiers<\/a><\/li>\n
  2. Types of Variable<\/a><\/li>\n
  3. Enums in Java<\/a><\/li>\n
  4. List of Java Keywords<\/a><\/li>\n
  5. The Interface Keyword<\/a><\/li>\n<\/ol>\n

    <\/p>\n\n\n

    1. Java Modifiers<\/h4>\n\n\n\n

    Modifiers are keywords used to add additional meaning or restriction to classes, methods, or variables. The two categories of java modifiers are<\/p>\n\n\n\n

    • Access Modifiers: public, protected, private, default<\/li>
    • Non-Access Modifiers: final, abstract, strictfp<\/li><\/ul>\n\n\n\n

      <\/p>\n\n\n\n

      2. Types of Variables in Java<\/h4>\n\n\n\n

      As you already know, variables are memory locations for storing data. Names of variables are chosen by the programmer. Therefore, Java provide three different categories of variable that can be used<\/p>\n\n\n\n

      • Local Variables<\/li>
      • Class Variables (declared using the static keyword)<\/li>
      • Instance Variable<\/li><\/ul>\n\n\n\n

        <\/p>\n\n\n\n

        3. Enums in Java<\/h4>\n\n\n\n

        Another important keyword in Java is enum. You can use Enum to limit a the values of a variable to some predefined values. These predefined values are called enums.<\/p>\n\n\n\n

        For example, we may have an application that uses a variable color. Since you want color to be limited to only certain values, you can use enum to create a list of colors. As such, color cannot be assigned a value that is not actually a color. <\/p>\n\n\n\n

        An example is given in Listing 1.0. If you run the code, you could see that the output is green<\/p>\n\n\n

        <\/p>\n

        \n
        \/\/Your Testing Enum<\/span>\npublic<\/span> class<\/span> EnumExample<\/span> {<\/span>\n\tenum<\/span> color{<\/span>red,<\/span> blue,<\/span> green,<\/span> yellow,<\/span> pink,<\/span> orange}<\/span>\n\tpublic<\/span> static<\/span> void<\/span> main<\/span>(<\/span>String[]<\/span> args)<\/span> {<\/span>\t\n\t\tcolor myColor =<\/span> color.<\/span>green<\/span>;<\/span>\n\t\tSystem.<\/span>out<\/span>.<\/span>println<\/span>(<\/span>myColor);<\/span>\n\t\tcolor myColor =<\/span> \"yello\"<\/span>;<\/span>   \/\/compiletime error!<\/span>\n\t}<\/span>\n}<\/span>\n<\/pre>\n<\/div>\n
        Listing 1.0: Example of the Enum keyword<\/p>\n\n\n
        In the example above, you can only assign to myColor, a value that is in the enum list. Therefore, if you try to assign any value not in the enum list to myColor, you  will have  an error<\/p>\n\n\n\n
        <\/p>\n\n\n\n
        4. List of Java Keywords<\/h4>\n\n\n\n
        You can find list of Java keywords in Table 1.0. You cannot use any of these keywords cannot be used to name identifier.<\/p>\n\n\n
        <\/p>\n\n\n
        abstract<\/td>assert<\/td>boolean<\/td>break<\/td><\/tr>
        byte<\/td>case<\/td>catch<\/td>char<\/td><\/tr>
        class<\/td>const<\/td>continue<\/td>default<\/td><\/tr>
        do<\/td>double<\/td>else<\/td>enum<\/td><\/tr>
        extends<\/td>final<\/td>finally<\/td>float<\/td><\/tr>
        for<\/td>goto<\/td>if<\/td>implements<\/td><\/tr>
        import<\/td>instanceof<\/td>int<\/td>interface<\/td><\/tr>
        long<\/td>native<\/td>new<\/td>package<\/td><\/tr>
        private<\/td>protected<\/td>public<\/td>return<\/td><\/tr>
        short<\/td>static<\/td>strictfp<\/td>super<\/td><\/tr>
        switch<\/td>synchronized<\/td>this<\/td>throw<\/td><\/tr>
        throws<\/td>transient<\/td>try<\/td>void<\/td><\/tr>
        volatile<\/td>while<\/td><\/td><\/td><\/tr><\/tbody><\/table>\n\n\n
        Table 1.0: List of Java Keywords<\/p>\n
        <\/p>\n\n\n
        5. The Interface Keyword<\/h4>\n\n\n\n
        Finally we would briefly learn about Interfaces. An interface is a class can  only be inherited. You use interface keyword to create a class that needs not be instantiated.<\/p>\n\n\n\n
        An example of interface in Java is given in Listing 1.1 below<\/p>\n\n\n
        <\/p>\n
        public<\/span> interface<\/span> Shape<\/span> {<\/span>\n\tpublic<\/span> void<\/span> render<\/span>();<\/span> \n\t\n\tpublic<\/span> void<\/span> getType<\/span>();<\/span>\n}<\/span>\n<\/pre>\n<\/div>\n
        Listing 1.1: Example of Java Interface<\/p>\n\n\n
        In the above example, we have created an interface called Shape. The two methods, render() and getType() are not implemented here. Therefore they must be implemented by a class that implements this interface. We would learn more about interfaces in subsequent lessons<\/p>\n","protected":false},"excerpt":{"rendered":"
        In this tutorial, we would examine various Java keywords beginning with Java Modifiers We would cover the following. Java Modifiers Types of Variable Enums in … <\/p>\n","protected":false},"author":395,"featured_media":23,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_monsterinsights_skip_tracking":false,"_monsterinsights_sitenote_active":false,"_monsterinsights_sitenote_note":"","_monsterinsights_sitenote_category":0,"footnotes":""},"categories":[2],"tags":[],"class_list":["post-22","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-java-tutorial"],"_links":{"self":[{"href":"https:\/\/kindsonthegenius.com\/java\/wp-json\/wp\/v2\/posts\/22","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/kindsonthegenius.com\/java\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/kindsonthegenius.com\/java\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/kindsonthegenius.com\/java\/wp-json\/wp\/v2\/users\/395"}],"replies":[{"embeddable":true,"href":"https:\/\/kindsonthegenius.com\/java\/wp-json\/wp\/v2\/comments?post=22"}],"version-history":[{"count":1,"href":"https:\/\/kindsonthegenius.com\/java\/wp-json\/wp\/v2\/posts\/22\/revisions"}],"predecessor-version":[{"id":24,"href":"https:\/\/kindsonthegenius.com\/java\/wp-json\/wp\/v2\/posts\/22\/revisions\/24"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/kindsonthegenius.com\/java\/wp-json\/wp\/v2\/media\/23"}],"wp:attachment":[{"href":"https:\/\/kindsonthegenius.com\/java\/wp-json\/wp\/v2\/media?parent=22"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/kindsonthegenius.com\/java\/wp-json\/wp\/v2\/categories?post=22"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/kindsonthegenius.com\/java\/wp-json\/wp\/v2\/tags?post=22"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}