Java 1.6 arraylist对象无法转换为字符串

Question

I have a problem trying to read the contents in my peakperiod list. The error I have received is java.lang.object cannot be cast to java.lang.String.
Are there any possible workaround for this problem as I am using java 1.6?

Delegate.java

 List peakPeriod = new ArrayList();  
 try{
     peakPeriod = Dao.retrievePeakPeriod("2017");
 for (Iterator i=peakPeriod.iterator(); i.hasNext(); {
     System.out.println("Peak Periods:"+(String)i.next());
 }
 catch(Exception e){ System.out.println("Error:"+e);}

Dao.java

public List retrievePeakPeriod(String year) throws DataAccessException;

DaoImpl.java

public List retrievePeakPeriod(String year) throws DataAccessException {
    List list = getHibernateTemplate().find("select cal.startdate,cal.enddate from Calendar cal " +
            "where to_char(cal.startdate,'yyyy') = ?",
            new Object[] { year },
            new Type[] { Hibernate.STRING });

    return list;
}

Answer 1

System.out.println("Peak Periods:"+ i.next());

You don't have to cast it to a String - java will automatically call the toString() method, so the above is equivalent to:

System.out.println("Peak Periods:"+ i.next().toString());

If your list can have nulls, you can do something safer such as:

System.out.println("Peak Periods:"+ String.valueOf(i.next()));

Edit: This assumes that the object returned has a useful toString representation and it's what you want. Otherwise, you'd need to figure out the type (class) of (the) object that's returned and do with it what you want.