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[英]How to get access to a HashMap of objects from the Objects in that HashMap. (Java)
[英]Is there any way to get the single value from hashmap.?
當我嘗試從
HashMap
檢索值時,我使用getValue
方法。 但是getValue
方法位於Struts2的迭代標記中,因此,它甚至顯示不需要的值。 我如何避免這種情況? 在我的JSP頁面上,我正在這里創建表,我想在其中設置<th>
標記中來自數據庫的orderdate
。 我的意思是從HashMap
我正在接收orderdate
,結果, dataamount
,count。 在<th>
我要orderdate
坐下,在<tr>
我要剩余的三個值坐下。 我怎么做 ?
import java.sql.Connection;
import java.sql.ResultSet;
import java.sql.Statement;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.Iterator;
import java.util.List;
import java.util.Map;
import java.util.Map.Entry;
import java.util.Set;
public class JanuaryAction {
private String from; // creating variables to access input values.
private String to; // creating variables to access input values.
Map abc1 = new HashMap(); // Getting the map objects to store tha values
public Map getAbc1() { /* Creating the setters and getters */
return abc1;
}
public void setAbc1(Map abc1) {
this.abc1 = abc1;
}
public String getFrom() {
return from;
}
public void setFrom(String from) {
this.from = from;
}
public String getTo() {
return to;
}
public void setTo(String to) {
this.to = to;
}
public Map<String, String> getAbc() {
return abc;
}
public void setAbc(Map<String, String> abc) {
this.abc = abc;
}
Map<String, String> abc = new HashMap<String, String>();
Map<String, List<ReportClass>> map = new HashMap<String, List<ReportClass>>(); // Using
// Map
// interface
// implementing
// hashmap
public Map<String, List<ReportClass>> getMap() {
return map;
}
public void setMap(Map<String, List<ReportClass>> map) {
this.map = map;
}
public String execute() throws Exception {
String fromdate = getFrom();
System.out.println(fromdate);
String todate = getTo();
System.out.println(todate);
Connection con = GetCon.getCon();
Statement statement = con.createStatement();
ResultSet resultset = statement
.executeQuery("SELECT MarketPlace,OrderDate, ROUND(SUM(Total),2), COUNT(*) , ROUND(ROUND(SUM(Total),2)/ COUNT(*),2) FROM vend_printed WHERE OrderDate >='"
+ fromdate + "' AND OrderDate <='" + todate + "' GROUP BY OrderDate,MarketPlace");
while (resultset.next()) {
String marketplace = resultset.getString(1);// get the first column
// in marketplace
String orderdate = resultset.getString(2);// get the second column
// in orderdate
Double datamount = resultset.getDouble(3);// get the third column in
// datamount
Integer count = resultset.getInt(4);// get the fourth column in
// count
Double result = resultset.getDouble(5); // get the fifth column in
// result
ReportClass a = new ReportClass(); // create an object to access
// pojo class.
a.setMarketplace(marketplace); // setting the values in pojo class
a.setOrderdate(orderdate);
a.setDataamount(datamount);
a.setCount(count);
a.setResult(result);
if (map.get(marketplace) != null) { // if the value in marketplace
// is null then go to else
// statement or go to if
// statement.
map.get(marketplace).add(a); // using the key add one complete
// row values from a to
// marketplace
} else {
List<ReportClass> optionsVO = new ArrayList<ReportClass>(); // create
// a
// list
// optionsVo
optionsVO.add(a); // store Reportclass values in List.
map.put(marketplace, optionsVO); // storing it in map.
/* System.out.println(map.get(marketplace).toString()); */
}
}
Set s = map.entrySet(); // A map entry (key-value pair).creating Set
// interface.
Iterator i = s.iterator();
while (i.hasNext()) {
List<ReportClass> tempList = (List<ReportClass>) ((Entry) i.next()).getValue(); // creating
// a
// temporary
// list
for (ReportClass reportClassObj : tempList) {
System.out.println(reportClassObj.getMarketplace());// display
// values.
System.out.println(reportClassObj.getDataamount());
System.out.println(reportClassObj.getOrderdate());
System.out.println(reportClassObj.getCount());
System.out.println(reportClassObj.getResult());
}
}
/* System.out.println(map.size()); */
return "success";
}
}
在我的jsp中,我有一個代碼。
<s:iterator var="studentEntry" status="stat" value="map.entrySet()">
Key: <s:property value="%{#studentEntry.getKey()}"/>
Value: <s:property value="%{#studentEntry.getValue()}"/><br>
</s:iterator>
不管您是對條目進行分組,都必須先對組進行迭代,然后再逐組訪問其他條目,以獲取所有值或選擇要進行迭代的組。
<s:iterator value="map">
<s:iterator var="studentEntry" value="value">
ReportClass: <s:property value="%{#studentEntry.toString()}"/><br>
</s:iterator>
</s:iterator>
實際上,您不需要使用entrySet
只需將map
變量用作<s:iterator>
標記的value
屬性,並將value
關鍵字用作第二個迭代器的值。 然后,您可以在<s:property>
標簽中的迭代器中直接引用ReportClass
<s:property>
。
<s:iterator value="map">
<s:iterator value="value">
<table>
<tr><th colspan="3"><s:property value="orderdate"/></th></tr>
<tr>
<td><s:property value="dataamount"/></td>
<td><s:property value="count"/></td>
<td><s:property value="result"/></td>
</tr>
</table>
</s:iterator>
</s:iterator>
試試下面的代碼,它必須工作。
<s:iterator value="map">
<s:iterator value="key">
<s:iterator value="value">
<th><s:property value="orderdate"/></th>
<td rowspan="4"><s:property value="marketplace"/></td>
<tr> <td><s:property value="dataamount"/></td></tr>
<tr><td><s:property value="count"/></td></tr>
<tr><td><s:property value="result"/></td></tr>
</s:iterator>
</s:iterator>
</s:iterator>
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