What does this mean: "from. <Integer>"?

Question

I saw a question about Builder criteria and came up with this question ...

What does it mean from.<Integer> get("...?

I have never seen a point of expression <Integer>.

Can someone show me an example?

Link: Compile error when using CriteriaBuilder

Code:

public List<BankAccount> findWithBalance(int amount) {
    CriteriaBuilder cb = em.getCriteriaBuilder();
    CriteriaQuery<BankAccount> cq = cb.createQuery(BankAccount.class);
    Root<BankAccount> from = cq.from(BankAccount.class);

    ParameterExpression<Integer> balance = cb.parameter(Integer.class);
    cq.select(from);

    //Here is the trick!
    Predicate predicate = cb.gt(from.<Integer> get("balance"), balance);

    cq.where(predicate);
    cq.orderBy(cb.asc(from.get("ownerName")));

    TypedQuery<BankAccount> query = em.createQuery(cq);

    query.setParameter(balance, amount);

    return query.getResultList();
}

Thanks!

Answer 1

This is a call to the generic method c Integerpassed as a type parameter.

Look here:

Java syntax for explicitly describing common arguments in method calls

http://docs.oracle.com/javase/specs/jls/se7/html/jls-15.html#jls-15.12

Answer 2

Java-. , . . . , :

void processStringList(List<String> stringList) {
    // process stringList
}

processStringList(Collections.emptyList()); // Compile error!
processStringList(Collections.<String>emptyList());  // Ok!

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Answer 3

Java Generics and Collections,

List<Integer> ints = Lists.<Integer>toList(); // first example
List<Object> objs = Lists.<Object>toList(1, "two"); // second example

• In the first example, , Sun . toList , , , . ( Eclipse .)
• In the second example, . , Object , , Serializable Comparable. , .

:

, , , , ; , .

, , , .

Java , , . toList , , :

List<Integer> ints = <Integer>toList(); // compile-time error

, .