Legacy classes in Java: What are they & Why Do They Matter?
Updated on Nov 14, 2022 | 6 min read | 7.0k views
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Updated on Nov 14, 2022 | 6 min read | 7.0k views
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Java, in its earliest versions, didn’t come with the Collection framework. Instead, it relied on defining specific classes and interfaces to store objects and their assigned methods. It wasn’t until J2SE 1.2 that the collection interface was introduced, which is commonly known as legacy classes in Java. Since then, these classes have been engineered to work correctly with Generics, and given below are some of the widespread usage of legacy classes:
Apart from the legacy classes, there is only one legacy interface in Java called the Enumeration.
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The legacy classes in Java are what was called as the ad hoc classes that used to contain values and object groups. Java 2 used to be missing a unified framework called the collections framework before it was introduced in Java 2. The objectives of such a framework are:
In general, a collections framework stands for combined infrastructure built for the representation and operating methods and variables. Developed around a predefined set of standard interfaces like LinkedList, HashSet, and more, these frameworks can be entirely used as per its presets or customized accordingly.
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Read more: A Guide to Iterator Implementation in Java
The Enumeration: It is a legacy interface by nature; it can enumerate several values into a collection of objects and is followed by an Iterator.
The Enumeration interface works similarly to that of its superseding Iterator as it obtains values one at a time. This method is also invoked by the legacy classes in Java-like that of the Vector and Properties for carrying out a few ways. Here are some characteristics of an Enumeration interface:
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The methods followed by the Enumeration interface are:
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The Legacy Methods include:
HashTable | HashMap |
This class is synchronized. | This class isn’t in sync. |
Thread-safe and takes more time to work | Faster in execution |
The key or the values can’t be null. | Both the key and the values can be invalid. |
The table order remains constant through time. | The map may or may not remain consistent throughout. |
That was all about legacy classes in Java, we hope you found that useful!
Also read: Java Developer Salary in India: For Freshers & Experienced
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