Php
Numbers
! There where times when we need to use objects insteed of primitives. Java provides wrapper classes for each primitive data types.
RunCode
class LearningApp {
public static void main(String[] args) {
/**
* All wrapper classes are subclasses of ...
* the abstract class Number
*/
Number no = new Float("22.33");
System.out.println(no.shortValue()); // 22
}
}
Autoboxing
! Autoboxing is the automatic conversion that Java compiler makes between the primites and the corresponding object wrapper classes. RunCode
import java.util.List;
import java.util.ArrayList;
class LearningApp {
public static void main(String[] args) {
List<Integer> li = new ArrayList<>();
/**
* You add int to the Integer object ...
* and still the code compiles
*/
for (int i=0; i<10; i++) {
li.add(i);
}
}
}
... 14 lines˄˄˄Random
Math.random works well when you need a single number. If you need to generate a series use java.util.Random. RunCode
class LearningApp {
public static void main(String[] args) {
int rand = (int) (Math.random()*100);
System.out.println(rand);
}
}
... 6 lines˄˄˄ CompleteTask
class LearningApp {
public static void main(String[] args) {
/**
* Declare Number no as float 22.23 ...
* Use object's shortValue() method and ...
* Display no as 22
*/
...
}
}
➥ Questions
CARD
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