我有一个值和标签的selectItem列表。数据从数据库中获取,selectItem列表具有以下值:
<1,100-500>
<2,1000-1500>
<3,500-1000>
这里1,2,3是selectItem列表的值,'100-500','1000-1500'和'500-1000'分别是标签。如您所见,列表已根据标签进行排序。但我的要求是列表应显示在下拉列表中:
100-500
500-1000
1000-1500
有人可以建议一个解决方案吗?
答案 0 :(得分:6)
如果您无法修改从DB中获取SelectItem实例的代码,以便按照您的意愿进行排序,那么您必须自己对它们进行排序:
// this gets you a list which is not sorted as you would like
List<SelectItem> list = getMasterValues("Staff Range");
// you need to sort the list before displaying it.
// To sort the list, you need a Comparator which will tell the sorting
// algorithm how to order the items
Comparator<SelectItem> comparator = new Comparator<SelectItem>() {
@Override
public int compare(SelectItem s1, SelectItem s2) {
// the items must be compared based on their value (assuming String or Integer value here)
return s1.getValue().compareTo(s2.getValue());
}
};
// now that you have the comparator, sort the list using it :
Collections.sort(list, comparator);
// and now iterate over the list to display it :
for (SelectItem item : list) {
System.out.println("value = " + item.getValue() + "; label = " + item.getLabel());
}
答案 1 :(得分:4)
这是我快速编写的一个示例程序,它使用custom comparator:
import java.util.ArrayList;
import java.util.Collections;
import java.util.Comparator;
import java.util.List;
import javax.swing.JLabel;
public class StrangeSort
{
static List<JLabel> listOfLabels = new ArrayList<JLabel>();
@SuppressWarnings("unchecked")
public static void main(String[] args)
{
listOfLabels.add(new JLabel("100-500"));
listOfLabels.add(new JLabel("1000-1500"));
listOfLabels.add(new JLabel("500-1000"));
System.out.println("Before:");
for(JLabel label: listOfLabels)
{
System.out.println(label.getText());
}
Collections.sort(listOfLabels, new LabelComparator());
System.out.println("After:");
for(JLabel label: listOfLabels)
{
System.out.println(label.getText());
}
}
static class LabelComparator implements Comparator
{
public int compare(Object obj1, Object obj2)
{
// Get labels
JLabel label1 = (JLabel) obj1;
JLabel label2 = (JLabel) obj2;
// Get text
String[] label1Text = label1.getText().split("-");
String[] label2Text = label2.getText().split("-");
// Convert to integers
int label1Value = Integer.parseInt(label1Text[0]);
int label2Value = Integer.parseInt(label2Text[0]);
// Compare values
if (label1Value > label2Value)
{
return 1;
}
else if (label1Value < label2Value)
{
return -1;
}
else
{
return 0;
}
}
}
}
输出:
Before:
100-500
1000-1500
500-1000
After:
100-500
500-1000
1000-1500
答案 2 :(得分:1)
答案 3 :(得分:1)
我使用Commons BeanUtils并用一行代码来完成它。...
// sort by label
Collections.sort(selectItems, new BeanComparator<>("label"));
或...
// sort by value
Collections.sort(selectItems, new BeanComparator<>("value"));
答案 4 :(得分:0)
查看“JB Nizet”发布的代码。它按价值排序。如果你改变了
return s1.getValue().compareTo(s2.getValue());
以下内容:
return s1.getLabel().compareTo(s2.getLabel());
它将按标签排序。
以上将按字符串值排序。这意味着1小于5(即1000 <500)。下一步是将标签转换为数字并进行比较。对于此用途,可以使用以下变体:
int value1 = Integer.parseInt(s1.getLabel());
int value2 = Integer.parseInt(s2.getLabel());
return value1 - value2;
答案 5 :(得分:0)
非常感谢你的帮助。我得到了理想的结果。请在下面找到代码供您参考。
/**
* This is a custom comparator used for numeric sorting based on labels
*/
static class LabelComparator implements Comparator {
public int compare(Object obj1, Object obj2) {
// Get labels
SelectItem label1 = (SelectItem) obj1;
SelectItem label2 = (SelectItem) obj2;
// Get text
String[] label1Text = label1.getLabel().split("-");
String[] label2Text = label2.getLabel().split("-");
// Convert to integers
int label1Value = Integer.parseInt(label1Text[0]);
int label2Value = Integer.parseInt(label2Text[0]);
// Compare values
if (label1Value > label2Value) {
return 1;
} else if (label1Value < label2Value) {
return -1;
} else {
return 0;
}
}
}
/**
* Method to populate values
*/
public void init() {
List rangeList = (List) CodeManagerUtil
.getValue("Staff Range");
Collections.sort(rangeList, new LabelComparator());
if (rangeList != null) {
setRangeList(rangeList );
}
}