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I likeThatMeow
Asked: 2020-09-26 18:23:28 +0800 CST 2020-09-26 18:23:28 +0800 CST

How can I print the values ​​of a TreeMap?

  • 772

This does not return anything to me: System.out.println(tree.values());, the castings do not work either, ie System.out.println((int)tree.values());

How do I get it to print the collection of key values?

Map<Integer,String> tree=new TreeMap<>();
tree.values();//Devuelve una colección de los valores contenidos en 
//este mapa.
System.out.println(tree.values());
java

2 Answers

  1. Best Answer

    valuesThe class method TreeMapreturns an object of type Collectionso it can't be printed like that unless you do an toStringal to it collection:System.out.println(tree.values().toString())

    To print a Collection, just go through it, you can use the foreach, in your case as the values ​​are of type String, it would look like this:

    for (String obj : tree.values()) {
   System.out.println(obj); // 
}

    If what you want is to print the keys, you can use the method tree.keySet()that returns a Setthat at the end also inherits from Collection so you can go through it in the same way:

    for (Integer obj : tree.keySet()) {
   System.out.println(obj); // 
}
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  2. As an addition to Ali's answer, using Java 8:

    // valores
tree.values().forEach(System.out::println);

// claves
tree.keySet().forEach(System.out::println);

// entradas
tree.entrySet().forEach(entry -> System.out.println("Clave: " + entry.getKey() + " -> Valor: " + entry.getValue()));
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