Minimal Java interpreter which only understands integer addition

Test.java

package test;

import com.github.javaparser.StaticJavaParser;
import com.github.javaparser.ast.expr.BinaryExpr;
import com.github.javaparser.ast.expr.IntegerLiteralExpr;
import com.github.javaparser.ast.visitor.GenericVisitorAdapter;

public class Test {

    public static void main(String[] args) {
        System.out.println(StaticJavaParser.parseExpression("1+2+3").accept(new IntegerLiteralVisitor(), null));
    }

    static class IntegerLiteralVisitor extends GenericVisitorAdapter<Integer, Void> {
        @Override
        public Integer visit(BinaryExpr n, Void arg) {
            Integer leftValue = n.getLeft().accept(this, arg);
            Integer rightValue = n.getRight().accept(this, arg);
            return leftValue + rightValue;
        }

        @Override
        public Integer visit(IntegerLiteralExpr integerLiteralExpr, Void arg) {
            return integerLiteralExpr.asNumber().intValue();
        }
    }
}

• "intValue" can fail in a very extreme case (see Javadoc)
• only integer literals and binary expressions are understood
• every binary expression is assumed to be an integer addition