22
33public class DynamicArray <T >{
44 //Just a demo.
5- public static void main (String []a ){
5+ public static void main (String []a )throws Exception {
66 // Could be DynamicArray<Object> ... =new DynamicArray<>();
77 DynamicArray <String > dynamics =new DynamicArray <String >();
88 dynamics .set (5 , "This is the fifth slot!" );
@@ -12,41 +12,72 @@ public static void main(String[]a){
1212 System .out .println (
1313 java .util .Arrays .toString (dynamics .getArray ())
1414 );
15- //Can throw ArrayIndexOutOfBounds if not used "properly".
15+ System .out .println ("But this is how it really looks like:" );
16+ System .out .println (
17+ java .util .Arrays .toString (dynamics .getRealArray ())
18+ );
19+ //Can throw ArrayIndexOutOfBoundsException if not used "properly".
1620 System .out .println (dynamics .get (10 ));
1721 dynamics =new DynamicArray <String >(
1822 new String []{"Hello?" , "Is" , "It" , "..." }
1923 );
2024 System .out .println (
2125 java .util .Arrays .toString (dynamics .getArray ())
2226 );
27+ System .out .println ("But this is how it really looks like:" );
28+ System .out .println (
29+ java .util .Arrays .toString (dynamics .getRealArray ())
30+ );
31+ System .out .println ("Pre initialized arrays are not automatically expanded until the #get() method is called." );
2332 }
24- //Would rather use a List<> to be honest.
2533 //The class itself
34+ //It's an empty array, we're not affecting any data at all.
35+ @ SuppressWarnings ("unchecked" )
36+ T [] underlyingArr =(T [])new Object [0 ];
37+ int size =0 ;
38+ int actualSize =0 ;
2639 public DynamicArray (){}
2740 public DynamicArray (final T [] newArr ){
2841 underlyingArr =newArr ;
42+ actualSize =newArr .length ;
43+ size =newArr .length ;
2944 }
30- //T is an Object, don't mind it too much.
31- //Also, it's an empty array, we're not affecting any data at all.
32- @ SuppressWarnings ("unchecked" )
33- T [] underlyingArr =(T [])new Object [0 ];
3445 public void set (final int ind , final T value ){
35- if (underlyingArr . length <ind +1 ){
46+ if (actualSize <ind +1 ){
3647 //It's an empty array, we're not affecting any data at all.
3748 @ SuppressWarnings ("unchecked" )
38- final T [] duplicate =(T [])new Object [ind +1 ];
49+ final T [] duplicate =(T [])new Object [ind +10 ];
3950 System .arraycopy (
40- underlyingArr , 0 , duplicate , 0 , underlyingArr . length
51+ underlyingArr , 0 , duplicate , 0 , actualSize
4152 );
53+ actualSize =ind +10 ;
4254 underlyingArr =duplicate ;
4355 }
56+ if (size <ind +1 )
57+ size =ind +1 ;
4458 underlyingArr [ind ]=value ;
4559 }
46- public T get (final int ind ){
60+ public T get (final int ind )throws ArrayIndexOutOfBoundsException {
61+ if (ind >size -1 )
62+ throw new ArrayIndexOutOfBoundsException (
63+ new StringBuilder ("Index " )
64+ .append (String .valueOf (ind ))
65+ .append (" out of bounds for length " )
66+ .append (size )
67+ .toString ()
68+ );
4769 return underlyingArr [ind ];
4870 }
71+ public T [] toArray (){
72+ return getArray ();
73+ }
4974 public T [] getArray (){
75+ @ SuppressWarnings ("unchecked" )
76+ final T [] returnMe =(T [])new Object [size ];
77+ System .arraycopy (underlyingArr , 0 , returnMe , 0 , size );
78+ return returnMe ;
79+ }
80+ public T [] getRealArray (){
5081 return underlyingArr ;
5182 }
5283}
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