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Flatten an array of arbitrarily nested arrays of integers into a flat array of integers in Java
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package com.citrusbyte; | |
import java.util.ArrayList; | |
import java.util.List; | |
public class MyClass { | |
public static void main(String[] args) { | |
/** Array to be flatten **/ | |
Object[] inputArray = new Object[]{ | |
new Object[]{1, 2, new Object[]{3, new Object[]{14,45,78,new Object[]{8,56,85}}}}, | |
new Object[]{4, 22,new Object[]{11,9,29,66}, 51,33,new Object[]{18,42,new Object[]{8,new Object[]{92,50,101},85}}}, | |
new Object[]{6,69}, | |
new Object[]{100,} | |
}; | |
Object[] flatArray = flatten(inputArray); | |
printArray(flatArray); | |
} | |
/** | |
* @param array - Array to be processed; | |
* @return the flat array; | |
*/ | |
public static Object[] flatten(Object[] array){ | |
List<Integer> list = new ArrayList<Integer>(); | |
for (int j = 0; j < array.length; j++) { | |
Integer a = getChildElement(array[j], list); | |
if(a != null) { | |
list.add((int) a); | |
} | |
} | |
return list.toArray(); | |
} | |
/** | |
* Search the object which is an integer and add it to a list. * | |
* @param obj - the item from the list; | |
* @param list - a list which will save the integers; | |
* @return | |
*/ | |
private static Integer getChildElement(Object obj, List<Integer> list) { | |
if(obj instanceof Integer){ | |
list.add((int) obj); | |
return (int) obj; | |
}else{ | |
Object[] a = (Object[]) obj; | |
for (int j = 0; j < a.length; j++) { | |
getChildElement(a[j], list); | |
} | |
} | |
return null; | |
} | |
/** | |
* Print the result | |
* @param list - flat array | |
*/ | |
public static void printArray(Object[] list){ | |
String comma= ","; | |
System.out.print("flatten array = {"); | |
for (int i = 0 ; i < list.length ; i++){ | |
if(i >= list.length - 1){ | |
comma = ""; | |
} | |
System.out.print(list[i] + comma); | |
} | |
System.out.print("};"); | |
} | |
} |
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