3- A Poor Solution

Jun 20, 2026 04:56 · 3:22 · English · Whisper Turbo · 2 speakers

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Lecture Index

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S… Speaker 1 (3- A Poor Solution)

One way to solve the problem in the last video is to use an area of objects here

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because the object class is the base or the parent of all reference types

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in Java.

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Remember reference types?

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We talked about them in the first part of this series.

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To refresh your memory,

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we have two categories of types in Java.

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Primitive types and reference types.

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Primitive types are numbers,

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characters,

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and booleans.

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Everything else is a reference type.

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So if we use an array of objects here,

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we can store anything in this array.

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For example,

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we can store user objects because the user class extends the object

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class.

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So let's replace all these integers with the object class.

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So here we have an object array and here

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as well, the parameter of the add method should be an object and

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also the return type of the get method should be an object.

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S… Speaker 2 (3- A Poor Solution)

Now,

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back to our main class.

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We can store numbers in this array.

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We can also store strings.

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We can also store user

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objects.

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So that's great,

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isn't it?

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Not really.

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This is a very bad solution for a couple of reasons.

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But before we talk about these reasons,

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I've got a question for you.

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Earlier I told you that the object class is the parent of all reference

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types, so we can store any objects in this list.

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However,

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this integer here,

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this is a primitive value,

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it's not an object,

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it's not a reference type.

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So how can we store it here?

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S… Speaker 2 (3- A Poor Solution)

Well,

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when we compile this code,

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the Java compiler will convert this code to something like this.

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Integer dot value of 1.

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So we have this integer class in Java,

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it's a reference type,

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it derives from the object class.

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And this class has a static method,

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valueof,

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which returns a new instance of the integer class.

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So this is the reason why we can pass a primitive value to this method.

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By the same token,

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we have a wrapper class for every primitive type in Java.

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We have float,

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we have double,

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boolean,

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character,

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and so on.

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Okay,

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so let's revert this back.

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What are the problems with this implementation?

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Well,

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the first problem is that if you want to get the first item in this list,

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we call the get method.

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Now,

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we know that this is an integer,

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so we may hope to store it in an integer variable called number.

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but we have a compilation error because this get method returns an object,

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but we expect an integer.

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So here we have to explicitly cast the result to

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an integer.

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And this makes our code a little bit verbose and noisy.

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The second problem is that if we use the wrong type here,

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we'll get an invalid cast exception.

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For example,

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let's change 0 to 1.

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We know that the second item in this list is a string.

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What if we accidentally try to cast it to an integer?

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We run our program,

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we get a class cast exception.

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Now the problem here is that we will not be aware of bugs like this

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until we run our application and test all the functions.

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So we can only identify these problems at runtime.

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It would be great if we could catch these problems at compile time.

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And that's what generics are for.

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In the next video,

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I will show you how generic classes help us solve these problems.

This transcript was generated by AI (automatic speech recognition). May contain errors — verify against the original audio for critical use. AI policy

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