CODEWITHSUNDEEP
javahashset
user2811419
user2811419

Reputation: 1973

Accessing data in a set

I have created this new set and want to add items to the set. But it won't get into the loop. I tried running the program and it would not display in the for loop. I am not sure hwy or how I would change the code for it to work. 

Set<Name> names = Sets.newHashSet();

      for (Name n : names) {
         System.out.println("in the for loop");
         n.setName("Tom);
}

Upvotes: 1

Views: 102

Answers (1)

JB Nizet
JB Nizet

Reputation: 692121

Here's what your program does, in English:

 Set<Name> names = Sets.newHashSet();

Let's create a new empty set of names, that we'll call "names"

for (Name n : names) {

Let's iterate through all the names present in the empty set we have just created. This obviously is useless, since the set is empty.

    System.out.println("in the for loop");

Let's write to the console that we're in the loop. This will never be executed, since the set is empty.

    n.setName("Tom);

Let's change the name of the current Name object in the loop. But since the loop is never executed, it will never happen.

Before iterating over elements in a set, add elements to the set:

Name n = new Name("Tom"); // this creates an new object of type Name
names.add(n); // this adds the Name we just created to the set. 
              // Now the set has 1 element.

If you want to add several names to the set, you can also use a loop, and create and ad a new Name at each iteration:

for (int i = 0; i < 10; i++) {
    Name n = new Name("Tom " + i);
    names.add(n);
}
// now the set contains 10 elements: Tom 0, Tom 1, ..., Tom 9

Upvotes: 5

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