javagenericsreturnreturn-typeconsumer

Difference between 'void' and ' <T> void' in java method

public static <T> void myMethod(int a, Consumer<T> consumer){// Some code}

public static void myMethod(int a, Consumer<T> consumer){// Some code}

Difference between 'void' and '<T> void'

Solution

  • There is no such thing as <T> void. These are two entirely separate declarations (<T> and void) that happen to be next to each other:

    public static <T> void myMethod(int a, Consumer<T> consumer){/* Some code */}
//             │    │
//             │    └─ Declaration of method's return type
//             │
//             └────── Declaration of a generic type which is used only
//                     by this method

    And how is this different?

    public static void myMethod(int a, Consumer<T> consumer){/* Some code */}

    In the above line, <T> is not declared anywhere, so the declaration will not compile. (If the method were not static, it could use the <T> declared on the enclosing class, assuming the enclosing class declares a <T> type.)