帮助遍历ArrayList仅获得特定结果

问题描述

| 我有一个返回许多结果的SQL查询（不幸的是，结果数会有所不同）。目前，我将结果存储到arrayList中，如下所示：

ArrayList allTerms = new ArrayList();


try {

  String selStmt = \"SELECT .... \";

  stmt = conn.prepareStatement(selStmt);
  result = stmt.executeQuery();
  Object result_data;

  while (result.next()) {    
      term = (((result_data = result.getobject(\"internal_code\"))==null || result.wasNull())?\" \":result_data.toString());
      allTerms.add(term);
      desc = (((result_data = result.getobject(\"external_representation\"))==null || result.wasNull())?\" \":result_data.toString());
      allTerms.add(desc);
      sorter = (((result_data = result.getobject(\"sorter\"))==null || result.wasNull())?\" \":result_data.toString());
      allTerms.add(sorter);
      sDate = (((result_data = result.getobject(\"sDate\"))==null || result.wasNull())?\" \":result_data.toString());
      allTerms.add(sDate);
  }
  System.out.println(allTerms);

好的，所以当我运行它时，系统将打印：

[2011SP,Spring 2011,1,11-15-2010,2011SU,Summer 2011,01-15-2011,2011FL,Fall 2011,04-01-2011,2010Q2,CE Qtr 2 2010 Dec - Feb,2,08-01-2010,2011Q3,CE Qtr 3 2011 Mar - May,11-01-2010,2011Q4,CE Qtr 4 2011 Jun - Aug,02-01-2011,2011Q1,CE Qtr 1 2011 Sep-Nov,05-01-2011]

我不知道这是否是正确的方法，但是到目前为止它仍在工作，所以我现在想做的是使用allTerms arrayList将这些结果传输到HTML页面的各个部分。因此，例如：

<table class=\"t1\">
  <tr>
    <td><!--Here I would want to show all rows from the allTerms arrayList with a \"sorter\" of 1--></td>
  </tr>
</table>
<table class=\"t2\">
  <tr>
    <td><!--Here I would want to show all rows from the allTerms arrayList with a \"sorter\" of 1 and a term of ....SU (where \'....\' is the year) --></td>
  </tr>
</table>

    

解决方法

        如果您只定义一个短值持有者类，则容易得多，例如：

public class Row {  // give it a better name ;)
  public String internalCode;
  public String externalRepresentation;
  public String sorter;
  public String sDate;
}

然后，定义一个保存以下行值的集合：

List<Row> rows = new ArrayList<Row>();

并将行添加到列表中：

while (result.next()) {    
      Row row = new Row();
      row.internalCode = (((result_data = result.getObject(\"internal_code\"))==null || result.wasNull())?\" \":result_data.toString());
      row.externalRepresentation = (((result_data = result.getObject(\"external_representation\"))==null || result.wasNull())?\" \":result_data.toString());
      row.sorter = (((result_data = result.getObject(\"sorter\"))==null || result.wasNull())?\" \":result_data.toString());
      row.sDate = (((result_data = result.getObject(\"sDate\"))==null || result.wasNull())?\" \":result_data.toString());      
}

现在您可以像这样过滤集合：

 for (Row row:rows) {
   if (!row.sorter.equals(\"1\"))
     continue;

   // do what has to be done with records where sorter = \"1\"
 }