我对下一个电话有疑问!
我写了一段代码,它必须计算一个关键字在我的ArrayList中出现了多少次;但是当循环中出现偶数时;它不起作用!
我知道这里有很多解决的问题;但是我不能解决我的代码中的错误。下面是我的代码:
public static ResultSet getBins(Connection conn, String tableName){
ResultSet distinctBin = null;
try {
Statement distinctBinsSt = conn.createStatement(
ResultSet.TYPE_SCROLL_INSENSITIVE,
ResultSet.CONCUR_UPDATABLE);
distinctBin = distinctBinsSt.executeQuery("select bin, placedescr from " + tableName + " ORDER BY bin ASC limit 151");
}catch(SQLException e){e.printStackTrace();}
return distinctBin;
}
public static Map <String,Integer> placeDescCounter(ArrayList<String> binDescription ){
Map<String, Integer> wordCount = new HashMap<String, Integer>();
FlickrReader tagfileReader = new FlickrReader();
for (String placeTag: binDescription)
{
Integer count = wordCount.get(placeTag);
wordCount.put(placeTag, (count==null) ? 1 : count+1);
}
return wordCount;
}
public static ResultSet getBinInfo(Connection conn, String tableName){
ResultSet binInfo = null;
try {
Statement binInfoSt = conn.createStatement(
ResultSet.TYPE_SCROLL_INSENSITIVE,
ResultSet.CONCUR_UPDATABLE);
binInfo = binInfoSt.executeQuery("select bin, count(bin) from " + tableName + " group by bin order by bin ASC;");
binInfo.last();
binInfo.beforeFirst();
}catch(SQLException e){e.printStackTrace();}
return binInfo;
}
public static void main(String[] args) throws SQLException, ClassNotFoundException{
Connection conn = connectPG();
String tableName= "tagcounterdebug";
ResultSet bins = getBins(conn, tableName);
ResultSet binsInfo = getBinInfo(conn,tableName);
String placeDescriptions;
List<String> placeDescription;
ArrayList<String> binDescriptions = new ArrayList<String>();
int bin =0;
bins.last();bins.beforeFirst();
while(binsInfo.next()){
int defaultBin = binsInfo.getInt("bin");
int binSize = binsInfo.getInt("count");
printDebug("loop conter " + (binSize - 1));
bins.next();
for (int i=0; i < binSize; i++){
bin = bins.getInt("bin");
placeDescriptions = bins.getString("placedescr").toLowerCase();
placeDescriptions = placeDescriptions.substring(placeDescriptions.indexOf("[")+1 , placeDescriptions.indexOf("]"));
placeDescription = Arrays.asList(placeDescriptions.split("\\s*;\\s*"));
HashSet<String> hashSetDescriptions = new HashSet<String>();//create a HashSet for tokens to calculate less
hashSetDescriptions.addAll(placeDescription);
binDescriptions.addAll(hashSetDescriptions);
bins.next();
}
printDebug("****\n defBin: " +defaultBin + " bin: " +bin + "\n****");
Map<String, Integer> tagCount = new HashMap<String, Integer>();
tagCount = placeDescCounter(binDescriptions);
for (String name: tagCount.keySet()){
String key =name.toString();
String value = tagCount.get(name).toString();
System.out.println(key + " " + value);
}
}
}
}
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2条答案
按热度按时间dgiusagp1#
这个错误出现了,因为我限制了我可以从DB中获取的行;它不能通过循环。
xj3cbfub2#
你调用了
.next()
两次,内部调用将把ResultSet定位在它的最后一个元素之后,因为你没有检查它的返回值。