declare variables in Java<\/a> as pictorially depicted below as a visual aid.From the image, it can be easily perceived that while declaring a variable, we need to take care of two things that are:<\/p>\n\n\n\n
datatype:<\/strong> Type of data that can be stored in this variable. <\/p>\n\n\n\ndata_name<\/strong>: Name was given to the variable.<\/p>\n\n\n\n\nHow to Initialize Variables in Java?<\/strong><\/li>\n<\/ul>\n\n\n\nIt can be perceived with the help of 3 components that are as follows:<\/p>\n\n\n\n
datatype:<\/strong> Type of data that can be stored in this variable.<\/p>\n\n\n\nvariable_name:<\/strong> Name given to the variable.<\/p>\n\n\n\nvalue:<\/strong> It is the initial value stored in the variable.\nTypes of Variables in Java<\/strong><\/li>\n<\/ul>\n\n\n\nNow let us discuss different types of variables which are listed as follows: <\/p>\n\n\n\n
\nLocal Variables<\/li>\n\n\n\n Instance Variables<\/li>\n\n\n\n Static Variables<\/li>\n<\/ul>\n\n\n\n1. Local Variables <\/strong><\/p>\n\n\n\nA variable defined within a block or method or constructor is called a local variable. <\/p>\n\n\n\n
\nThese variables are created when the block is entered, or the function is called and destroyed after exiting from the block or when the call returns from the function.<\/li>\n\n\n\n The scope of these variables exists only within the block in which the variables are declared, i.e., we can access these variables only within that block.<\/li>\n\n\n\n Initialization of the local variable is mandatory before using it in the defined scope.<\/li>\n<\/ul>\n\n\n\nBelow is the implementation of the above approach:<\/p>\n\n\n\n
Class hcl guvi {\n public static void main(String[] args)\n {\n \/\/ Declared a Local Variable\n int var = 10;\n \n \/\/ This variable is local to this main method only\n System.out.println(\"Local Variable: \" + var);\n }\n}\n<\/code><\/pre>\n\n\n\n2. Instance Variables<\/strong><\/p>\n\n\n\nInstance variables are non-static variables and are declared in a class outside of any method, constructor, or block. <\/p>\n\n\n\n
\nAs instance variables are declared in a class, these variables are created when an object of the class is created and destroyed when the object is destroyed.<\/li>\n\n\n\n Unlike local variables, we may use access specifiers for instance variables. If we do not specify any access specifier, then the default access specifier will be used.<\/li>\n\n\n\n Initialization of an instance variable is not mandatory. Its default value is dependent on the data type of variable. <\/li>\n\n\n\n Instance variables can be accessed only by creating objects.<\/li>\n\n\n\n We initialize instance variables using constructors while creating an object. We can also use instance blocks to initialize the instance variables.<\/li>\n<\/ul>\n\n\n\n\/\/ Java Program to demonstrate\nclass hcl guvi {\n\t\/\/ Declared instance variable\n\tString student = \"Shubham Jain\";\n\tpublic static void main(String[] args)\n\t{\n hcl Guvi Zen=new hcl Guvi();\n\t\t\/\/ geek variable can be accessed by creating object\n\n\tSystem.out.print(Zen. student); }\n}\n<\/code><\/pre>\n\n\n\n3. Static Variables<\/strong><\/p>\n\n\n\nStatic variables are also known as class variables. <\/p>\n\n\n\n
\nThese variables are declared similarly to instance variables. The difference is that static variables are declared using the static keyword within a class outside of any method, constructor, or block.<\/li>\n\n\n\n Unlike instance variables, we can only have one copy of a static variable per class, irrespective of how many objects we create.<\/li>\n\n\n\n Static variables are created at the start of program execution and destroyed automatically when execution ends.<\/li>\n\n\n\n Initialization of a static variable is not mandatory. Its default value is dependent on the data type of variable.<\/li>\n<\/ul>\n\n\n\n\/\/ Java Program to demonstrate\nclass hcl guvi {\n\t\/\/ Declared instance variable\n\tPublic static String student = \"Shubham Jain\";\n\tpublic static void main(String[] args)\n\t{\n \n\t\/\/ student variable can be accessed without object\n \/\/ static variable\n\n\tSystem.out.print(hcl guvi. student); }}\n\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0<\/code><\/pre>\n\n\n\n\nScope of variables <\/strong>Operators in Java<\/strong><\/h3>\n\n\n\nOperators in Java are the symbols used for performing specific operations in Java. Operators make tasks like addition, multiplication, etc. which look easy although the implementation of these tasks is quite complex.<\/p>\n\n\n\n
Types of Operators in Java :<\/strong><\/p>\n\n\n\n\nArithmetic Operators<\/strong><\/li>\n<\/ol>\n\n\n\nThese operators involve the mathematical operators that can be used to perform various simple or advanced arithmetic operations on the primitive data types referred to as the operands. These operators consist of various unary and binary operators that can be applied on a single or two operands.
\nUnary Operators in Java<\/strong><\/li>\n<\/ol>\n\n\n\nJava unary operators are the types that need only one operand to perform any operation like increment, decrement, negation, etc. It consists of various arithmetic, logical and other operators that operate on a single operand. Let\u2019s look at the various unary operators in detail and see how they operate.
\nAssignment Operators<\/strong><\/li>\n<\/ol>\n\n\n\nThese operators are used to assign values to a variable. The left side operand of the assignment operator is a variable, and the right side operand of the assignment operator is a value. The value on the right side must be of the same data type of the operand on the left side. Otherwise, the compiler will raise an error. This means that the assignment operators have right to left associativity.
\nRelational Operators<\/strong><\/li>\n<\/ol>\n\n\n\nJava Relational Operators are a bunch of binary operators used to check for relations between two operands, including equality, greater than, less than, etc. They return a boolean result after the comparison and are extensively used in looping statements as well as conditional if-else statements and so on.
\nLogical Operators<\/strong><\/li>\n<\/ol>\n\n\n\nLogical operators are used to perform logical \u201cAND\u201d, \u201cOR\u201d and \u201cNOT\u201d operations, i.e. the function similar to AND gate and OR gate in digital electronics. They are used to combine two or more conditions\/constraints or to complement the evaluation of the original condition under particular consideration. One thing to keep in mind is, while using AND operator, the second condition is not evaluated if the first one is false. Whereas while using OR operator, the second condition is not evaluated if the first one is true<\/p>\n\n\n\n
\nTernary Operator<\/strong><\/li>\n<\/ol>\n\n\n\nJava ternary operator is the only conditional operator that takes three operands. It\u2019s a one-liner replacement for the if-then-else statement and is used a lot in Java programming. We can use the ternary operator in place of if-else conditions or even switch conditions using nested ternary operators.<\/p>\n\n\n\n
Syntax:<\/strong><\/p>\n\n\n\nvariable = Expression1 ? Expression2 : Expression3<\/code><\/pre>\n\n\n\n
\n <\/strong>Type Casting in Java :<\/strong><\/li>\n<\/ul>\n\n\n\nIn Java, type casting is a method or process that converts a data type into another data type in both ways manually and automatically. The automatic conversion is done by the compiler and manual conversion is performed by the programmer. In this section, we will discuss type casting and its types with proper examples.<\/p>\n\n\n\n\u00b7<\/strong> <\/strong>Type casting<\/strong><\/p>\n\n\n\nConverting a value from one data type to another data type is known as type casting. <\/p>\n\n\n\n
Types of Type Casting<\/p>\n\n\n\n
There are two types of type casting:<\/p>\n\n\n\n
1. Widening Type Casting<\/p>\n\n\n\n
2. Narrowing Type Casting<\/p>\n\n\n\n
\n <\/strong>Widening Type Casting<\/strong><\/li>\n<\/ul>\n\n\n\nConverting a lower data type into a higher one is called widening type casting. It is also known as implicit conversion or casting down. It is done automatically. It is safe because there is no chance to lose data. It takes place when:<\/p>\n\n\n\n
o Both data types must be compatible with each other.<\/p>\n\n\n\n
o The target type must be larger than the source type<\/p>\n\n\n\nbyte -> short -> char -> int -> long -> float -> double <\/strong><\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\nFor example, the conversion between numeric data types to char or Boolean is not done automatically. Also, the char and Boolean data types are not compatible with each other. Let’s see an example.<\/p>\n\n\n\n
public class WideningTypeCastingExample \n{ \npublic static void main(String[] args) \n{ \nint x = 7; \n\/\/automatically converts the integer type into long type \nlong y = x; \n\/\/automatically converts the long type into float type \nfloat z = y; \nSystem.out.println(\"Before conversion, int value \"+x); \nSystem.out.println(\"After conversion, long value \"+y); \nSystem.out.println(\"After conversion, float value \"+z); \n} \n} \n<\/code><\/pre>\n\n\n\nOutput:<\/p>\n\n\n\n
![\"java](\"https:\/\/lh7-rt.googleusercontent.com\/docsz\/AD_4nXdRrB_0rkqruvAakAQUiXPmrg3nz7KvcITqFYVe4wg6D05svTPTlTiyHFgACb9KSC6n1kSbCAYeZygzvTps1TT_D-ZzTy8uh4l-PyACbVtpAeNe5EnJpdHdV_FR5GgX2dK51Pe5yOLklpK-d8Qq8IZakOmNtXupl5lR-P8YGExvIufQRQcrMw?key=54X4JSqCb0hCWp9Uuj_IZQ\" "\\"\\"")
<\/figure>\n\n\n\n![\"\"](\"https:\/\/lh7-rt.googleusercontent.com\/docsz\/AD_4nXdSjUn9SA7qa4K2r8lNdqZbKnfp5I-ENmaBwYPT1tjjFiNxDtyhkOUynoIot7o0NpTFSMVBFqHNZfXHJoRDfibpUU2dZNjXF9SdCj_U5ZgAGnIobdQdAm9Co9jtcwVPBU7pzey7nu1WSplbnqLRIalU9oq2UxBQIRACQ2sVSQ6H9vgWQMuL-0g?key=54X4JSqCb0hCWp9Uuj_IZQ\" "\\"\\"")
<\/p>\n\n\n\n![\"\"](\"https:\/\/lh7-rt.googleusercontent.com\/docsz\/AD_4nXdMSz5cVPl20ROsdClEJOLzmc9ADarUwUDhatSpdG1rFQDzWv0feKcvf5NRVL5yTnkNHNpbUcmX2rG61Sg216BJ1kdcdZraEQS_-jABmQxiGtQychEldotz0rBmtXve9kqglvcg1AqZ_6IHfsKZFPDo4vMLihL64Y0_VcfSap5tbB4JWYqGyHA?key=54X4JSqCb0hCWp9Uuj_IZQ\" "\\"\\"")
<\/p>\n\n\n\n![\"\"](\"https:\/\/lh7-rt.googleusercontent.com\/docsz\/AD_4nXeX3WRouB_htNDlHqRGylrHpinlpj-sdKiJIR8Hj60s3Ymcz2ojH9FfYbCbXF6ncvsLNVm0OmAje90qu5il160UMorulHEOENWaV2F7afQTrqRHvHY4ECYBwWZFyWFAoZI0WY6RRuzkiF1HkPm0zEZyZA6AnjXGsV_HNIh4jvAjbJbZHopFLg?key=54X4JSqCb0hCWp9Uuj_IZQ\" "\\"\\"")
<\/p>\n\n\n\n![\"\"](\"https:\/\/lh7-rt.googleusercontent.com\/docsz\/AD_4nXe7L027eqWSeC76dX5FRIntZ_y8uMZG1J6b9Mbz7letICiVD9-wojQnNAIpq3Mz-FL4BCXEzTpENZlG1M0JOvP_bi_0YNpQGMBoZbt8c9-6qVMw8UHqOoxRpiPHjjUjlOx7LdSEdSfOYqQJEOZ_zHdbdTgjcfht4fePCz8sQmMzuleazQQ1teo?key=54X4JSqCb0hCWp9Uuj_IZQ\" "\\"\\"")
<\/p>\n\n\n\n![\"\"](\"https:\/\/lh7-rt.googleusercontent.com\/docsz\/AD_4nXe8IxLxBxDSky3FyNwk6WtH0duVIwGyfeNDK9QTp6_2If8Jncfn4HUjOg8TXNanL734hlIbJl1H2LLdPSQcnazlQ-4K4HmjCZiVJyfFORGmIQZ4rV5p1hY4sZ8dvinxMNvmhqjOEL0eC3LxcGxKNejXwbKNWlEY9WtxPeDf9xbgJlQgIwQcEw?key=54X4JSqCb0hCWp9Uuj_IZQ\" "\\"\\"")
<\/p>\n\n\n\n![\"\"](\"https:\/\/lh7-rt.googleusercontent.com\/docsz\/AD_4nXe5tMzTW8F_SMgGC_o3hAt6QPXHdI9ueIj2_zK4pxvAHcsU5wkipHSVy4FivHH1I6ryI6v_P4N0ZNpWBSvOv6H4eNnvpk9MC0ZrQW0_Iw5UpUNqQ4bZ53UZUtzb0dca7C05DZ5Nn-SU5gFY1yaR4YALB2vsO3EZLkuOSGRPpBN0Ylr-ePcSQA?key=54X4JSqCb0hCWp9Uuj_IZQ\" "\\"\\"")
<\/p>\n\n\n\n![\"\"](\"https:\/\/lh7-rt.googleusercontent.com\/docsz\/AD_4nXc_DuNeoDRFiYYPduCI1NqmXxXdqCtslUPdXKX4xHLWNRiWq1Rarmevr1oxqpMyke2SnwT0Id5v4MuZtp_oKKjsquA5fZSF0Hc-KgM_DYjeboCXWJt_M_6H5E7wzZc9XB5FLx0SWt-MmeRY5mYPp9mtciocwPaRFwq7AA54OGrMXILYchoTIw?key=54X4JSqCb0hCWp9Uuj_IZQ\" "\\"\\"")
<\/li>\n<\/ul>\n\n\n\n![\"\"](\"https:\/\/lh7-rt.googleusercontent.com\/docsz\/AD_4nXdIf7qBxK_d9pZYGUCU2YiF2eRaA1j_m6XM3avaf-6fakI2EfugEN_T2PTQE_62ftdNB5CuE6OCHI7zeGJFmRDp9VvZoTKbIZTB5VQotnHp8jTgQu5daXycZEea3SXzjFEXeGWZNGahnkWzAliQjVXJ0T-WA02RselZguxOQM_ZsT0kYCYvN4s?key=54X4JSqCb0hCWp9Uuj_IZQ\" "\\"\\"")
<\/p>\n\n\n\n![\"\"](\"https:\/\/lh7-rt.googleusercontent.com\/docsz\/AD_4nXfIrIKijTiUR54C6AhpMs9bbo7w_GQce87hFRutXuFVBXTGanGzAcVNe7Sd6B8pJKKGBBPmo79P6XV_V5A8oXVqXo26s9D8M6Jt7zxER191sqT-bp7_UZCJ9xotLnfw2Eb6x1rnsXu8CYiWFdp9HpCyFR3YWN2GGUuB1EBmP6vEMbv-hHb1u94?key=54X4JSqCb0hCWp9Uuj_IZQ\" "\\"\\"")
<\/p>\n\n\n\n![\"\"](\"https:\/\/lh7-rt.googleusercontent.com\/docsz\/AD_4nXc2LFN3OYgKW2VSlVa7BxJvOAbybeF5V1pZGbQywi1pBaEzSFGjFmbxtCoKrEzzpguPaXSohKDfkpZRwhm9FCkwhTP-JOj-bn2PdlhKRgoEyJAez0la9_nP7BwwcQZtUb7djdTcV_2jhcKwQnuruT3u8eM92j2nGWJp7PJ-iIVdqxRoyNetq30?key=54X4JSqCb0hCWp9Uuj_IZQ\" "\\"\\"")
<\/p>\n\n\n\n![\"\"](\"https:\/\/lh7-rt.googleusercontent.com\/docsz\/AD_4nXfwIrcv_WtbcSLoZl_chbdxfKwty2uTJ0LwfETKa-yTC4YHC69Ljwf_8PJrODao3q-UnrVgNwnDrkWdF7Pz6-SE7BXz0i7FBVbDQoKZMy_-WfxPFgDgeY8FIlb8dQTYIrk83rwSv-CIIB56kiBjPqlAlo-ID8_wQe8n1e3oDrHMxwVFFtT_fg?key=54X4JSqCb0hCWp9Uuj_IZQ\" "\\"\\"")
<\/p>\n\n\n\n![\"\"](\"https:\/\/lh7-rt.googleusercontent.com\/docsz\/AD_4nXeHlNtr8tb5rYpSElNbTIHX-DMkXrxS_i_jfWlGyqTgS9br5123QusG2xE7A-FjKczSGVuh4Figt1F4ojAUN2Q59fMn8oTdLWgp8phQsABnFGjmAydLntqHahlbboulCMpo8Rn6Gc6j0CSj0Sj30GsVBQqDB2r72qXUQRp9TLs4GIrPrOJj1dM?key=54X4JSqCb0hCWp9Uuj_IZQ\" "\\"\\"")
<\/p>\n\n\n\n![\"\"](\"https:\/\/lh7-rt.googleusercontent.com\/docsz\/AD_4nXf-r29Lcnq7c2oMkREHB1vcnI7d09loN90Q-iEBKEifKjFx82ua3OLKqJwyfhQmVSLK8o_DrRqcynGOM-Iy9dM8C45mqiYzDUL_388ypGZZ5cKDVq3ex8-NTy6yeF6bMAFdM-DJJ4LBpnyzWhtbeCUkgU0u81KxnRj65VnGSUrvorxNH3tAmQ?key=54X4JSqCb0hCWp9Uuj_IZQ\" "\\"\\"")
<\/p>\n\n\n\n![\"Type](\"https:\/\/lh7-rt.googleusercontent.com\/docsz\/AD_4nXcPzxf-OcVv4IcR05dp6B6_sKQ3f6D44xfBv1jSVr3hy2f1himoVdv9OKDAT6v0FRhBM3R--fJtc8D8GtXnCo8KqtH4jlJVbnUAFb7sQhD9J5TKS-n-CGTSEOjAQmGNqibKij_UOEAvwoTz-cUMuPL5tdQK8lgncQYYgFV40jygYeG5xYA7Gm4?key=54X4JSqCb0hCWp9Uuj_IZQ\" "\\"\\"")
<\/figure>\n\n\n\n