関連ワード:  is class a data type in java    is class a primitive data type in java    is class a composite data type in java    is class a reference data type in java    is class a user defined data type in java    is class a non primitive data type in java    is string a class or data type in java    why is a class known as composite data type in java    in java the string class is a primitive data type    is class a data type