Examples with ElementGroup org.apache.jena.sparql.syntax.ElementGroup used on opensource projects

Example 36 with ElementGroup

use of org.apache.jena.sparql.syntax.ElementGroup in project jena by apache.

the class ExProg2 method main.

public static void main(String[] args) {
    Model model = createModel();
    Query query = QueryFactory.make();
    query.setQuerySelectType();
    // See also ExProg1
    ElementGroup elg = new ElementGroup();
    Var varTitle = Var.alloc("title");
    Var varX = Var.alloc("x");
    Triple t1 = new Triple(varX, DC.title.asNode(), varTitle);
    elg.addTriplePattern(t1);
    // Adds a filter.  Need to wrap variable in a NodeVar.
    Expr expr = new E_Regex(new ExprVar(varTitle), "sparql", "i");
    ElementFilter filter = new ElementFilter(expr);
    elg.addElementFilter(filter);
    // Attach the group to query.
    query.setQueryPattern(elg);
    // Choose what we want - SELECT ?title
    query.addResultVar(varTitle);
    // Print query with line numbers
    // Prefix mapping just helps serialization
    query.getPrefixMapping().setNsPrefix("dc", DC.getURI());
    query.serialize(new IndentedWriter(System.out, true));
    System.out.println();
    try (QueryExecution qexec = QueryExecutionFactory.create(query, model)) {
        // Assumption: it's a SELECT query.
        ResultSet rs = qexec.execSelect();
        // The order of results is undefined.
        System.out.println("Titles: ");
        for (; rs.hasNext(); ) {
            QuerySolution rb = rs.nextSolution();
            // Get title - variable names do not include the '?' (or '$')
            RDFNode x = rb.get("title");
            // Check the type of the result value
            if (x instanceof Literal) {
                Literal titleStr = (Literal) x;
                System.out.println("    " + titleStr);
            } else
                System.out.println("Strange - not a literal: " + x);
        }
    }
}

Example 37 with ElementGroup

use of org.apache.jena.sparql.syntax.ElementGroup in project jena by apache.

the class ExProg1 method main.

public static void main(String[] args) {
    Model model = createModel();
    Query query = QueryFactory.make();
    query.setQuerySelectType();
    // Build pattern
    ElementGroup elg = new ElementGroup();
    Var varTitle = Var.alloc("title");
    Var varX = Var.alloc("x");
    Triple t1 = new Triple(varX, DC.title.asNode(), varTitle);
    elg.addTriplePattern(t1);
    // Don't use bNodes for anon variables.  The conversion is done in parsing.
    // BNodes here are assumed to be values from the target graph.
    Triple t2 = new Triple(varX, DC.description.asNode(), Var.alloc("desc"));
    elg.addTriplePattern(t2);
    // Attach the group to query.
    query.setQueryPattern(elg);
    // Choose what we want - SELECT *
    // query.setQueryResultStar(true) ;
    query.addResultVar(varTitle);
    // Print query with line numbers
    // Prefix mapping just helps serialization
    query.getPrefixMapping().setNsPrefix("dc", DC.getURI());
    query.serialize(new IndentedWriter(System.out, true));
    System.out.println();
    try (QueryExecution qexec = QueryExecutionFactory.create(query, model)) {
        // Assumption: it's a SELECT query.
        ResultSet rs = qexec.execSelect();
        // The order of results is undefined.
        System.out.println("Titles: ");
        for (; rs.hasNext(); ) {
            QuerySolution rb = rs.nextSolution();
            // Get title - variable names do not include the '?' (or '$')
            RDFNode x = rb.get("title");
            // Check the type of the result value
            if (x instanceof Literal) {
                Literal titleStr = (Literal) x;
                System.out.println("    " + titleStr);
            } else
                System.out.println("Strange - not a literal: " + x);
        }
    }
}