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Java Array Exercises: Convert an ArrayList to an array

Java Array: Exercise-21 with Solution

Write a Java program to convert an ArrayList to an array.

Pictorial Presentation:

Java Array Exercises: Convert an ArrayList to an array

Sample Solution:

Java Code :

import java.util.ArrayList;
  import java.util.Arrays;
  public class Exercise21 {
  public static void  main(String[] args)
  {
  ArrayList<String> list = new ArrayList<String>();

  list.add("Python");
 
  list.add("Java");
 
  list.add("PHP");
  
  list.add("C#");
 
  list.add("C++");
  
  list.add("Perl");
 
  String[]  my_array = new String[list.size()];
  
  list.toArray(my_array);
  
  for (String  string : my_array)
  {
  System.out.println(string);
  }
  }
  }

Sample Output:

Python                                                                                                
Java                                                                                                
PHP                                                                                                
C#                                                                                                
C++                                                                                                
Perl 

Flowchart:

Flowchart: Java exercises: Convert an ArrayList to an array

Visualize Java code execution (Python Tutor):


Java Code Editor:

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Java: Tips of the Day

Different between parseInt() and valueOf() in java?

Well, the API for Integer.valueOf(String) does indeed say that the String is interpreted exactly as if it were given to Integer.parseInt(String). However, valueOf(String) returns a new Integer() object whereas parseInt(String) returns a primitive int.

If you want to enjoy the potential caching benefits of Integer.valueOf(int), you could also use this eyesore:

Integer k = Integer.valueOf(Integer.parseInt("123"))

Now, if what you want is the object and not the primitive, then using valueOf(String) may be more attractive than making a new object out of parseInt(String) because the former is consistently present across Integer, Long, Double, etc.

Ref: https://bit.ly/3vRuIPY