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Java Generics - 1. Introduction

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This is part 1 of the 9 part series on Java Generics  If someone asks me - what are the best features of Java programming since the release of 1.5? I will vouch for two of them - Generics and Annotations . What makes Generics so special is the compile time checking of a type, the restrictions on the usage of a class it provides and simply its elegance. What amazes me however, is that the programmers rarely use the full power of Generics that Java programming language provides. So I thought of writing down a series of blogs that can be used by the programmers to understand and use them. There are a series of 9 blogs on the topic. They were too large to be adjusted into just one. So, just like in programming, I decided to 'divide and conquer'. Topics 1. Introduction 2. Bounding 3. Multiple bounding 4. Generic Methods 5. Wildcards 6. Typed Classes as method parameters 7. Upper and Lower Bounds 8. Target Types 9. Type Erasure Next Topic ...
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Java Generics - 6. Typed Classes as method parameters

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This is part 6 of the 9 part series on Java Generics  Prev Topic Wildcards Topics 1. Introduction 2. Bounding 3. Multiple bounding 4. Generic Methods 5. Wildcards 6. Typed Classes as method parameters 7. Upper and Lower Bounds 8. Target Types 9. Type Erasure Next Topic Upper and Lower Bounds Java Generics - Typed Classes as Method Parameters We saw in the previous section, that List which is a typed interface can be used either with the wildcard (?) or with a defined type E , ‘ E extends Number’ in this case. Can we use it with a Fruit that is exportable? Why not, the rules are same. Here is a method which gives the maximum price for all Exportable fruits in a list. public static <E extends Fruit & Exportable> double maxPrice1(List<Bean<E>> beans ){        double max = 0;        fo...
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Java Generics - 5. Wildcards

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This is part 5 of the 9 part series on Java Generics  Prev Topic Generic Methods Topics 1. Introduction 2. Bounding 3. Multiple bounding 4. Generic Methods 5. Wildcards 6. Typed Classes as method parameters 7. Upper and Lower Bounds 8. Target Types 9. Type Erasure Next Topic Typed Classes as method parameters Java Generics - Wildcards “?” wildcard in Java, means “any”. If a method takes in a declaration with <?>, it means it can take any type. Say you’d like to perform a certain operation which applies to all types (usually for a library class) , then this wildcard can be handy. Say you want a method which gives back the size of the list, but you also want to handle ‘null’ scenarios. Then you could write the code as:        public static int getSize(List<?> list ){               re...
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