This topic is about Java Generics – Multiple Bounds.
A type parameter can have multiple bounds.
Syntax
public static <T extends Number & Comparable<T>> T maximum(T x, T y, T z)
Where
- maximum − maximum is a generic method.
- T − The generic type parameter passed to generic method. It can take any Object.
Description
The T is a type parameter passed to the generic class Box and should be subtype of Number class and must implments Comparable interface. In case a class is passed as bound, it should be passed first before interface otherwise compile time error will occur.
Example
Create the following java program using any editor of your choice.
package com.tutorialspoint;
public class GenericsTester {
public static void main(String[] args) {
System.out.printf("Max of %d, %d and %d is %d\n\n",
3, 4, 5, maximum( 3, 4, 5 ));
System.out.printf("Max of %.1f,%.1f and %.1f is %.1f\n\n",
6.6, 8.8, 7.7, maximum( 6.6, 8.8, 7.7 ));
}
public static <T extends Number
& Comparable<T>> T maximum(T x, T y, T z) {
T max = x;
if(y.compareTo(max) > 0) {
max = y;
}
if(z.compareTo(max) > 0) {
max = z;
}
return max;
}
// Compiler throws error in case of below declaration
/* public static <T extends Comparable<T>
& Number> T maximum1(T x, T y, T z) {
T max = x;
if(y.compareTo(max) > 0) {
max = y;
}
if(z.compareTo(max) > 0) {
max = z;
}
return max;
}*/
}
This will produce the following result −
Output
Max of 3, 4 and 5 is 5 Max of 6.6,8.8 and 7.7 is 8.8
In this topic we learned about Java Generics – Multiple Bounds. To learn more, Click Here.