Type Casting

Type casting is when the data type of a variable is casted to another type. There are two types of casting: Widening and Narrowing.

Converting a Variable’s Type Using Widening Casting

With this type of casting, there is no extra code that needs to be written. Java does this for you under the hood when a smaller type is converted to a larger type. When dealing with numbers, a byte is the smallest data type (whole numbers from -128 to 127), then a short (whole numbers from -32,768 to 32,767), int (whole numbers from -2,147,483,648 to 2,147,483,647), long (whole numbers from -9,223,372,036,854,775,808 to 9,223,372,036,854,775,807), float (fractional numbers with 6 to 7 decimal places), and double (fractional numbers with 15 decimal places).

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    int intType = 2021;

    // casting at assignment

    float floatType = intType; // Outputs 2021.0

Converting a Variable’s Type Using Narrowing Casting

This casting is used when converting from a larger data type to a smaller type. For example, converting from a long to an int requires Narrowing casting. For example:

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    long longType = 2000000L;

    // Cast by wrapping the desired type in parentheses before the value

    int intType = (int) longType; // Outputs 2000000



    // won't work if the long value is greater or less than int's range

    longType = 3000000000L; // greater than the upper limit of int type

    // the data is cast to an int

    // since the long value is out of int's range, Java tries converting to a value within range

    intType = (int) longType; // Outputs -1294967296

Typecasting WYNTK

Typecasting doesn’t work for all data classes. Some may wonder if you can convert a char to a String and vice versa. Primitive data types are the only data types that can be casted in this manner. And since the String class is not a primitive type, it’s not allowed. There are, however, built in methods in the String class that help do this; like the String.valueOf(char c) method and in the Character class like Character.toString(char c).