How to display keys from Map<int[],Double>?

Question

I want to add x elements (just keys) from sorted map to list and display them.

public static ArrayList<int[]> miZrodzicowIpotomstwa(Map<int[],Double> mapVectFunc_tmp, int x)
{
 ArrayList<int[]> listaMi = new ArrayList<>();
 ArrayList<int[]> klucz_t = new ArrayList<>(mapVectFunc_tmp.keySet());
 for(int i=0; i<x; i++)
 {
 listaMi.add(klucz_t.get(i));
 }
 return listaMi;
}

in main:

Map<int[],Double> mapVectFunc = new LinkedHashMap<int[],Double>();
int []t1={1,0,0,1};
int []t2={1,1,0,0};
int []t3={1,0,1,1};
mapVectFunc.put(t1,26.0);
mapVectFunc.put(t2,1.0);
mapVectFunc.put(t3,6767.0);
ArrayList<int[]> ll= miZrodzicowIpotomstwa(mapVectFunc, 2);
System.out.printf("\n list of two keys: "+ll);

I received the following values(not arrays) :

list of two keys: [[I@54bedef2, [I@5caf905d]

Does anybody has an idea how to convert it into arrays?

• zeppelin: Possible duplicate of How to convert int[] into List<Integer> in Java?
• Sergey Kalinichenko: Display issue is just the tip of the iceberg here. You have a much bigger issue here: the map does not work. To see why, create three identical arrays of int, and use them as keys into the map. Observe how three items are added, then come up with a different strategy.

Answer 1

You can print them like this.

public static void main(String[] args) {
 Map<int[], Double> mapVectFunc = new LinkedHashMap<int[], Double>();
 int[] t1 = { 1, 0, 0, 1 };
 int[] t2 = { 1, 1, 0, 0 };
 int[] t3 = { 1, 0, 1, 1 };
 mapVectFunc.put(t1, 26.0);
 mapVectFunc.put(t2, 1.0);
 mapVectFunc.put(t3, 6767.0);
 ArrayList<int[]> ll = miZrodzicowIpotomstwa(mapVectFunc, 2);
 int c = 0;
 for (int[] i : ll) {
 System.out.println("Array" + c++);
 for (int j : i) {
 System.out.println(j);
 }
 } 
}

Answer 2

ArrayList<int[]> ll= miZrodzicowIpotomstwa(mapVectFunc, 2);
...
System.out.println("\n list of two keys: ");
for (int[] i: ll.keySet()){
 String key =i.toString();
 String value = ll.get(i).toString(); 
 System.out.println(key + " " + value); 
}

A little bit more here: Printing HashMap In Java

• Karolina Cabaj: The problem is that keys are arrays. Result: [I@54bedef2 26.0 [I@5caf905d 1.0 [I@27716f4 6767.0
• Vasyl Lyashkevych: Thanks, I am going to check

Answer 3

for (int[] i : l1){
 for(int j:i){
 System.out.println(j);
 }
}

• Karolina Cabaj: i received the same : [[I@54bedef2, [I@5caf905d]
• Binu: for (int[] i : l1){ for(int j:i){ System.out.println(j); } }

Answer 4

The problem is key in hash map.Please try with below code

public static void main(String[] args) {
 Map<Integer[], Double> mapVectFunc = new LinkedHashMap<Integer[], Double>();
 Integer[] t1 = { 1, 0, 0, 1 };
 Integer[] t2 = { 1, 1, 0, 0 };
 Integer[] t3 = { 1, 0, 1, 1 };
 mapVectFunc.put(t1, 26.0);
 mapVectFunc.put(t2, 1.0);
 mapVectFunc.put(t3, 6767.0);
 ArrayList<Integer> ll = miZrodzicowIpotomstwa(mapVectFunc, 2);
 System.out.printf("\n list of two keys: " + ll);
 }
 public static ArrayList<Integer> miZrodzicowIpotomstwa(Map<Integer[], Double> mapVectFunc_tmp, int x) {
 ArrayList<Integer> klucz_t = new ArrayList<>();
 for (Integer[] arr : mapVectFunc_tmp.keySet()) {
 ;
 klucz_t.addAll(Arrays.asList(arr));
 }
 return klucz_t;
 }