How does java.util.Map's getOrDefault() work?

Question

I noticed that if I do map.getOrDefault("key1", new Object()), even if object is present for `key1` in the map, `new Object()` is created. Though it is not returned by the method but it still creates it. For example, ``` public class Empl { private int id; private String name; public Empl(String name) { // TODO Auto-generated constructor stub System.out.println(name); this.name = name; } @Override public String toString() { // TODO Auto-generated method stub return name+id; } } ``` running following, ``` Map map = new HashMap(); Empl imp = new Empl("timon"); map.put("1", imp); System.out.println(map.getOrDefault("1", new Empl("dumnba"))); ``` gives this output: ``` timon dumnba timon0 ``` Shouldn't the default object be created only if it is not there in the map ? What is the reason if not ?

Accepted Answer

Shouldn't the default object be created only if it is not there in the map ?

How could that be the case? This call:

```
map.getOrDefault("1", new Empl("dumnba"))
```

is equivalent to:

```
String arg0 = "1";
Empl arg1 = new Empl("dumnba");
map.getOrDefault(arg0, arg1);
```

In other words, all arguments are evaluated before being passed to the method.

You could potentially use `computeIfAbsent` instead, but that will modify the map if the key was absent, which you may not want:

```
System.out.println(map.computeIfAbsent("1", k -> new Empl("dumnba")));
```

How does java.util.Map's getOrDefault() work?

Solution

Problem