What does "The constructor ... is ambiguous" mean?

Question

I would like to know what the error message in Eclipse means: The constructor Case(Problem, Solution, double, CaseSource) is ambiguous

Accepted Answer

The problem exists when you try to instantiate a class that could apply to more than one constructor.

For example:

```
public Example(String name) {
    this.name = name;
}

public Example(SomeOther other) {
    this.other = other;
} 
```

If you call the constructor with a String object, there's one definite constructor. However, if you instantiate `new Example(null)` then it could apply to either and is therefore ambiguous.

The same can apply to methods with similar signatures.