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I can NOT compile first class below

 
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I can NOT compile first class below I get the>>>.
//Chapter: 18-Generics, Problem - textbook:HTP7 JAVA DEITEL (c)2007, Exe.:18.4

C:\Users\User\Documents\TextBooksDataFiles\RexPractice\JAVA\MySolutions\18-4>javac SelectionSort.java
SelectionSort.java:53: incompatible types
found : T
required: T
T x = data[smallest];
^
SelectionSort.java:54: incompatible types
found : T
required: T
T y = data[index];
^
2 errors

 
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I changed your code to compile. I did not test it. I also don't know whether it will do what you intended it to do. In answer to your original queston, you were defining T at the class level and T at the method level so you had two Ts defined. In your original code, try changing the method T to, for example S and and the compiler error will not be so confusing. BTW, You cannot use primitive types with generics.

 
Leonidas Savvides
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exe instr: given an example in another chapter in selection sort[Searching/Sorting chapter], problem was use method sort with <T extends Comparable<T>>, and NOT class with this, to sort 10 numbers (in the original problem numbers in array random generated), well?

you say "try changing the method T to, for example S and and the compiler error will not be so confusing" how then bind T to S?
may wrtite this without in class the T but only in method: public < T extends Comparable< T >> void sort(T[] data) ???

BTW your code compiles and run correct.

To appear the contents of an obj array like Integer or Float I must use absolutelly: ENHANCED FOR LOOP correct?
 
Leonidas Savvides
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My code It compile/run success with below (is any error)?
can you comment on it (see and prior post)...

 
Tom Reilly
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Leonidas Savvides wrote:you say "try changing the method T to, for example S and and the compiler error will not be so confusing" how then bind T to S?

You cannot. T and S are different class types. I only suggested that to clear up confusion about the compiler error - not to remove the compiler error.

Leonidas Savvides wrote:To appear the contents of an obj array like Integer or Float I must use absolutelly: ENHANCED FOR LOOP correct?

No. See this recent post: https://coderanch.com/t/500383/java/java/operator-works-Integer-class
 
Leonidas Savvides
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well since My code It compile/run success with below (is any error/improvement)?
can you comment on it (see code in prior post)...
 
Tom Reilly
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Leonidas Savvides wrote:well since My code It compile/run success with below (is any error/improvement)?
can you comment on it (see code in prior post)...

I think they just wanted to show that you have choices in code design.
 
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