【发布时间】：2011-06-15 07:56:04
【问题描述】：
我有一个 listBox1 对象，它包含一些项目。我有一个按钮可以向上移动所选项目，另一个可以向下移动所选项目。这两个按钮的代码应该是什么？
【问题讨论】：
-
你在考虑客户端还是服务器端？
-
到目前为止您尝试过什么？仅仅指望别人为你工作是不公平的！
-
WinForms, WPF, ASP.NET ?
【发布时间】：2011-06-15 07:56:04
【问题描述】：
public void MoveUp()
{
MoveItem(-1);
}
public void MoveDown()
{
MoveItem(1);
}
public void MoveItem(int direction)
{
// Checking selected item
if (listBox1.SelectedItem == null || listBox1.SelectedIndex < 0)
return; // No selected item - nothing to do
// Calculate new index using move direction
int newIndex = listBox1.SelectedIndex + direction;
// Checking bounds of the range
if (newIndex < 0 || newIndex >= listBox1.Items.Count)
return; // Index out of range - nothing to do
object selected = listBox1.SelectedItem;
// Removing removable element
listBox1.Items.Remove(selected);
// Insert it in new position
listBox1.Items.Insert(newIndex, selected);
// Restore selection
listBox1.SetSelected(newIndex, true);
}
UPD 2020-03-24： 用于简单重用的扩展类，它还支持 CheckedListBox（如果您不需要 CheckedListBox，请删除相应的代码行）。谢谢@dognose 和@Chad
public static class ListBoxExtension
{
public static void MoveSelectedItemUp(this ListBox listBox)
{
_MoveSelectedItem(listBox, -1);
}
public static void MoveSelectedItemDown(this ListBox listBox)
{
_MoveSelectedItem(listBox, 1);
}
static void _MoveSelectedItem(ListBox listBox, int direction)
{
// Checking selected item
if (listBox.SelectedItem == null || listBox.SelectedIndex < 0)
return; // No selected item - nothing to do
// Calculate new index using move direction
int newIndex = listBox.SelectedIndex + direction;
// Checking bounds of the range
if (newIndex < 0 || newIndex >= listBox.Items.Count)
return; // Index out of range - nothing to do
object selected = listBox.SelectedItem;
// Save checked state if it is applicable
var checkedListBox = listBox as CheckedListBox;
var checkState = CheckState.Unchecked;
if (checkedListBox != null)
checkState = checkedListBox.GetItemCheckState(checkedListBox.SelectedIndex);
// Removing removable element
listBox.Items.Remove(selected);
// Insert it in new position
listBox.Items.Insert(newIndex, selected);
// Restore selection
listBox.SetSelected(newIndex, true);
// Restore checked state if it is applicable
if (checkedListBox != null)
checkedListBox.SetItemCheckState(newIndex, checkState);
}
}
【讨论】：
-
谢谢Save，你真的救了我嘿嘿;D简单客观！！工作完美！继续帮助我们；D +1
-
这段代码比公认的答案更抽象。我在代码中做的另一件事是添加一个
ListBox参数，这样函数就可以在任何ListBox上使用，只需将其传递给函数即可。 -
如果是
ChckedListBox，您可能还需要在移动之前添加这两行：CheckState checkState = checkedListBox1.GetItemCheckState(checkedListBox1.SelectedIndex);，并在末尾添加以下行：checkedListBox1.SetItemCheckState(newIndex, checkState);
private void UpClick()
{
// only if the first item isn't the current one
if(listBox1.ListIndex > 0)
{
// add a duplicate item up in the listbox
listBox1.AddItem(listBox1.Text, listBox1.ListIndex - 1);
// make it the current item
listBox1.ListIndex = (listBox1.ListIndex - 2);
// delete the old occurrence of this item
listBox1.RemoveItem(listBox1.ListIndex + 2);
}
}
private void DownClick()
{
// only if the last item isn't the current one
if((listBox1.ListIndex != -1) && (listBox1.ListIndex < listBox1.ListCount - 1))
{
// add a duplicate item down in the listbox
listBox1.AddItem(listBox1.Text, listBox1.ListIndex + 2);
// make it the current item
listBox1.ListIndex = listBox1.ListIndex + 2;
// delete the old occurrence of this item
listBox1.RemoveItem(listBox1.ListIndex - 2);
}
}
【讨论】：
-
ListIndex 对我不起作用。我改用了 Save 的答案。
你试过用谷歌搜索吗？以Move Items up/dowm in listbox control 为例。
public class SmartListBox : ListBox
{
//Moves the selected items up one level
public MoveUp()
{
for(int i = 0; i < Items.Count; i++)
{
if (Items[i].Selected)//identify the selected item
{
//swap with the top item(move up)
if (i > 0 && !Items[i - 1].Selected)
{
ListItem bottom = Items[i];
Items.Remove(bottom);
Items.Insert(i - 1, bottom);
Items[i - 1].Selected = true;
}
}
}
}
//Moves the selected items one level down
public MoveDown()
{
int startindex = Items.Count -1;
for (int i = startindex; i > -1; i--)
{
if (Items[i].Selected)//identify the selected item
{
//swap with the lower item(move down)
if (i < startindex && !Items[i + 1].Selected)
{
ListItem bottom = Items[i];
Items.Remove(bottom);
Items.Insert(i + 1, bottom);
Items[i + 1].Selected = true;
}
}
}
}
}
【讨论】：
-
方法中的返回类型在哪里
修改了@Save 代码以允许使用 DataSource 属性移动数据绑定到 ListBox 的项目。
public void MoveItem(int direction)
{
// Checking selected item
if (listBox1.SelectedItem == null || listBox1.SelectedIndex < 0)
return; // No selected item - nothing to do
// Calculate new index using move direction
int newIndex = listBox1.SelectedIndex + direction;
// Checking bounds of the range
if (newIndex < 0 || newIndex >= listBox1.Items.Count)
return; // Index out of range - nothing to do
UnifyCamera selected = listBox1.SelectedItem as UnifyCamera;
// modify the data source list
inputData.Cameras.RemoveAt(listBox1.SelectedIndex);
inputData.Cameras.Insert(newIndex, selected);
// re-bind your data source
((ListBox)listBox1).DataSource = null;
((ListBox)listBox1).DataSource = this.inputData.Cameras;
((ListBox)listBox1).DisplayMember = "Name";
// Restore selection
listBox1.SetSelected(newIndex, true);
}
UnifyCamera 是我的自定义类，它存储在返回 List<UnifyCamera> 的列表 inputData.Cameras 中。
【讨论】：
修改了上面的 Desolator 代码以将控件作为参数传递...可重用
private void MoveUp()
{
MoveItem(-1,listBox1);
}
private void MoveDown()
{
MoveItem(1,listBox1);
}
public void MoveItem(int direction,ListBox listBox)
{
// Checking selected item
if (listBox.SelectedItem == null || listBox.SelectedIndex < 0)
return; // No selected item - nothing to do
// Calculate new index using move direction
int newIndex = listBox.SelectedIndex + direction;
// Checking bounds of the range
if (newIndex < 0 || newIndex >= listBox.Items.Count)
return; // Index out of range - nothing to do
object selected = listBox.SelectedItem;
// Removing removable element
listBox.Items.Remove(selected);
// Insert it in new position
listBox.Items.Insert(newIndex, selected);
// Restore selection
listBox.SetSelected(newIndex, true);
}
【讨论】：
public static void MoveUpOrDownSelectedItem(ListBox LisBox, bool MoveUp)
{
if (LisBox.SelectedIndex > 0 && MoveUp)
{
// add a duplicate item up in the listbox
LisBox.Items.Insert(LisBox.SelectedIndex - 1, LisBox.SelectedItem);
// make it the current item
LisBox.SelectedIndex = (LisBox.SelectedIndex - 2);
// delete the old occurrence of this item
LisBox.Items.RemoveAt(LisBox.SelectedIndex + 2);
}
if ((LisBox.SelectedIndex != -1) && (LisBox.SelectedIndex < LisBox.Items.Count- 1) && MoveUp == false)
{
// add a duplicate item down in the listbox
int IndexToRemove = LisBox.SelectedIndex;
LisBox.Items.Insert(LisBox.SelectedIndex + 2, LisBox.SelectedItem);
// make it the current item
LisBox.SelectedIndex = (LisBox.SelectedIndex + 2);
// delete the old occurrence of this item
LisBox.Items.RemoveAt(IndexToRemove);
}
}
【讨论】：
所有其他答案都很好，但你也应该考虑这个:) 它的想法与 SwDevMan81 的想法很接近，但这是真实代码（不是伪代码） 并且您可以移动多个项目（多个选定项目） 并且在向下移动时有所改进。
private void MoveUp_listBox_button_Click(object sender, EventArgs e)
{
listBox.BeginUpdate();
int numberOfSelectedItems = listBox.SelectedItems.Count;
for (int i = 0; i < numberOfSelectedItems; i++)
{
// only if it's not the first item
if (listBox.SelectedIndices[i] > 0)
{
// the index of the item above the item that we wanna move up
int indexToInsertIn = listBox.SelectedIndices[i] - 1;
// insert UP the item that we want to move up
listBox.Items.Insert(indexToInsertIn, listBox.SelectedItems[i]);
// removing it from its old place
listBox.Items.RemoveAt(indexToInsertIn + 2);
// highlighting it in its new place
listBox.SelectedItem = listBox.Items[indexToInsertIn];
}
}
listBox.EndUpdate();
}
private void MoveDown_listBox_button_Click(object sender, EventArgs e)
{
listBox.BeginUpdate();
int numberOfSelectedItems = listBox.SelectedItems.Count;
// when going down, instead of moving through the selected items from top to bottom
// we'll go from bottom to top, it's easier to handle this way.
for (int i = numberOfSelectedItems-1; i >= 0; i--)
{
// only if it's not the last item
if (listBox.SelectedIndices[i] < listBox.Items.Count - 1)
{
// the index of the item that is currently below the selected item
int indexToInsertIn = listBox.SelectedIndices[i] + 2;
// insert DOWN the item that we want to move down
listBox.Items.Insert(indexToInsertIn, listBox.SelectedItems[i]);
// removing it from its old place
listBox.Items.RemoveAt(indexToInsertIn - 2);
// highlighting it in its new place
listBox.SelectedItem = listBox.Items[indexToInsertIn - 1];
}
}
listBox.EndUpdate();
}
【讨论】：
Vexe 的回答对我来说效果最好，但我不得不对其进行修改以解决几个问题。如果同一对象多次出现在列表框中，此解决方案将突出显示正确的对象。此外，此解决方案可以防止多选对象在到达列表框的顶部或底部并且继续多次按下按钮时发生翻转。
private void btnMoveUp_Click(object sender, EventArgs e)
{
// find the lowest index of non selected items
int lowestIndexNotSelected = listBox.Items.Count - 1;
for (int i = listBox.Items.Count - 1; i >= 0; i--)
{
if (!listBox.SelectedIndices.Contains(i))
{
lowestIndexNotSelected = i;
}
}
listBox.BeginUpdate();
int numberOfSelectedItems = listBox.SelectedItems.Count;
for (int i = 0; i < numberOfSelectedItems; i++)
{
// only if it's not a lower inde than the lowest non selected index
if (listBox.SelectedIndices[i] > lowestIndexNotSelected)
{
// the index of the item above the item that we wanna move up
int indexToInsertIn = listBox.SelectedIndices[i] - 1;
// insert UP the item that we want to move up
listBox.Items.Insert(indexToInsertIn, listBox.SelectedItems[i]);
// removing it from its old place
listBox.Items.RemoveAt(indexToInsertIn + 2);
// highlighting it in its new place (by index, to prevent highlighting wrong instance)
listBox.SelectedIndex = indexToInsertIn;
}
}
listBox.EndUpdate();
}
private void btnMoveDown_Click(object sender, EventArgs e)
{
// find the highest index of non selected items
int highestIndexNonSelected = 0;
for (int i = 0; i < listBox.Items.Count; i++)
{
if (!listBox.SelectedIndices.Contains(i))
{
highestIndexNonSelected = i;
}
}
listBox.BeginUpdate();
int numberOfSelectedItems = listBox.SelectedItems.Count;
// when going down, instead of moving through the selected items from top to bottom
// we'll go from bottom to top, it's easier to handle this way.
for (int i = numberOfSelectedItems - 1; i >= 0; i--)
{
// only if it's not a higher index than the highest index not selected
if (listBox.SelectedIndices[i] < highestIndexNonSelected)
{
// the index of the item that is currently below the selected item
int indexToInsertIn = listBox.SelectedIndices[i] + 2;
// insert DOWN the item that we want to move down
listBox.Items.Insert(indexToInsertIn, listBox.SelectedItems[i]);
// removing it from its old place
listBox.Items.RemoveAt(indexToInsertIn - 2);
// highlighting it in its new place (by index, to prevent highlighting wrong instance)
listBox.SelectedIndex = indexToInsertIn - 1;
}
}
listBox.EndUpdate();
}
【讨论】：
// Options is a list box
private void MoveUpButton_Click(object sender,EventArgs e) {
int index = Options.SelectedIndex;
if (index <= 0) return;
string item = (string)Options.Items[index - 1];
Options.Items.RemoveAt(index - 1);
Options.Items.Insert(index,item);
selectedIndexChanged(null,null);
}
private void MoveDnButton_Click(object sender,EventArgs e) {
int index = Options.SelectedIndex;
if (index + 1 >= Options.Items.Count) return;
string item = (string)Options.Items[index];
Options.Items.RemoveAt(index);
Options.Items.Insert(index + 1,item);
Options.SelectedIndex = index + 1;
}
// sent when user makes a selection or when he moves an item up or down
private void selectedIndexChanged(object sender,EventArgs e) {
int index = Selected.SelectedIndex;
MoveUpButton.Enabled = index > 0;
MoveDnButton.Enabled = index + 1 < Selected.Items.Count;
}
【讨论】：
private void btnUp_Click(object sender, System.EventArgs e)
{
if (this.lbItems.SelectedIndex == -1 || this.lbItems.SelectedIndex == 0)
return;
Object select, previous, temp;
select = lbItems.Items[lbItems.SelectedIndex];
previous = lbItems.Items[lbItems.SelectedIndex-1];
temp = select;
select = previous;
previous = temp;
lbItems.Items[lbItems.SelectedIndex] = select;
lbItems.Items[lbItems.SelectedIndex-1] = previous;
lbItems.SelectedIndex--;
}
private void btnDown_Click(object sender, System.EventArgs e)
{
if (this.lbItems.SelectedIndex == -1 || this.lbItems.SelectedIndex == lbItems.Items.Count-1)
return;
Object select, next, temp;
select = lbItems.Items[lbItems.SelectedIndex];
next = lbItems.Items[lbItems.SelectedIndex+1];
temp = select;
select = next;
next = temp;
lbItems.Items[lbItems.SelectedIndex] = select;
lbItems.Items[lbItems.SelectedIndex+1] = next;
lbItems.SelectedIndex++;
}
【讨论】：
-
想总结一下这对 2011 年提出的问题带来了哪些新问题？
对于那些正在寻找一种通用方式来处理可以绑定到数据源的 ListBox 的人，这里有一个基于 Save's answer 的通用扩展，它将处理常规和绑定的 ListBox。
public static void MoveUp(this ListBox listBox)
{
listBox.MoveItem(-1);
}
public static void MoveDown(this ListBox listBox)
{
listBox.MoveItem(1);
}
public static void MoveItem(this ListBox listBox, int direction)
{
// Checking selected item
if (listBox.SelectedItem == null || listBox.SelectedIndex < 0)
return; // No selected item - nothing to do
// Calculate new index using move direction
int newIndex = listBox.SelectedIndex + direction;
// Checking bounds of the range
if (newIndex < 0 || newIndex >= listBox.Items.Count)
return; // Index out of range - nothing to do
//Find our if we're dealing with a BindingSource
bool isBindingSource = listBox.DataSource is BindingSource;
//Get the list
System.Collections.IList list = isBindingSource ? ((BindingSource)listBox.DataSource).List : listBox.Items;
object selected = listBox.SelectedItem;
// Removing removable element
list.Remove(selected);
// Insert it in new position
list.Insert(newIndex, selected);
// Restore selection
listBox.SetSelected(newIndex, true);
if (isBindingSource)
{
//Reset the binding if needed
((BindingSource)listBox.DataSource).ResetBindings(false);
}
}
【讨论】：
获取所选项目的集合，然后按如下方式移动它们：
private void btnMoveUp_Click(object sender, EventArgs e)
{
HashSet<KeyValuePair<int, object>> ItemsToMove = new HashSet<KeyValuePair<int, object>>();
foreach (object o in lstMyListView.SelectedItems)
ItemsToMove.Add(new KeyValuePair<int, object>(lstMyListView.Items.IndexOf(o), o));
foreach (KeyValuePair<int, object> kvp in ItemsToMove)
{
if (kvp.Key > 0) // check if its the first item before moving
{
lstMyListView.Items.Remove(kvp.Value);
lstMyListView.Items.Insert(kvp.Key - 1, kvp.Value);
}
}
}
private void btnMoveDown_Click(object sender, EventArgs e)
{
HashSet<KeyValuePair<int, object>> ItemsToMove = new HashSet<KeyValuePair<int, object>>();
foreach (object o in lstMyListView.SelectedItems)
ItemsToMove.Add(new KeyValuePair<int, object>(lstMyListView.Items.IndexOf(o), o));
foreach (KeyValuePair<int, object> kvp in ItemsToMove)
{
if (kvp.Key < lstMyListView.Items.Count - 1) // check if its the last item before moving
{
lstMyListView.Items.Remove(kvp.Value);
lstMyListView.Items.Insert(kvp.Key + 1, kvp.Value);
}
}
}
【讨论】：
我写了这个函数来移动我选择的项目：
using System.Collections;
using System.Collections.Generic;
private void MoveListboxItems(int step, ListBox lb) {
/* 'step' should be:
* -1 for moving selected items up
* 1 for moving selected items down
* 'lb' is your ListBox
* see examples how to call below this function
*/
try {
// do only something when really an item is selected
if (lb.SelectedIndex > -1) {
// get some needed values - they change while we manipulate the listbox
// but we need them as they was original
IList SelectedItems = lb.SelectedItems;
IList SelectedIndices = lb.SelectedIndices;
// set some default values
int selIndex = -1;
int newIndex = -1;
int selCount = SelectedItems.Count;
int lc = 0;
int mc = 0;
string moveOldValue = string.Empty;
string selectedItemValue = string.Empty;
if (step == 1) {
mc = selCount - 1;
} else {
mc = lc;
}
// enter the loop through the selected items
while (lc < selCount) {
selectedItemValue = string.Empty;
moveOldValue = string.Empty;
try {
// get the item that should get moved
selectedItemValue = SelectedItems[mc].ToString();
selIndex = Convert.ToInt32(SelectedIndices[mc]);
} catch {
selIndex = -1;
}
// gen index for new place
newIndex = selIndex + step;
try {
// get the old value from the place where the item get moved
moveOldValue = lb.Items[newIndex].ToString();
} catch { /* do nothing */ }
try {
if (!String.IsNullOrEmpty(selectedItemValue) && !String.IsNullOrEmpty(moveOldValue) && selIndex != -1 && newIndex != -1 && !lb.SelectedIndices.Contains(newIndex)) {
// move selected item
lb.Items.RemoveAt(newIndex);
lb.Items.Insert(newIndex, selectedItemValue);
// write old value back to the old place from selected item
lb.Items.RemoveAt(selIndex);
lb.Items.Insert(selIndex, moveOldValue);
// hold the moved item selected
lb.SetSelected(newIndex, true);
}
} catch { /* do nothing */ }
lc++;
if (step == 1) {
mc -= step;
} else {
mc = lc;
}
}
}
} catch { /* do nothing */ };
}
// examples how i call the function above
void BtnLbUp_Click(object sender, EventArgs e) {
MoveListboxItems(-1, this.lbMyList);
}
void BtnLbDown_Click(object sender, EventArgs e) {
MoveListboxItems(1, this.lbMyList);
}
【讨论】：
向上按钮：
private void UpBottom_Click(object sender, EventArgs e)
{
//this.Options is ListBox
if (this.Options.SelectedIndex == -1 ||
this.Options.SelectedIndex == 0)
return;
string item, aboveItem;
int itemIndex, aboveItemIndex;
itemIndex = this.Options.SelectedIndex;
aboveItemIndex = this.Options.SelectedIndex - 1;
item = (string)this.Options.Items[itemIndex];
aboveItem = (string)this.Options.Items[aboveItemIndex];
this.Options.Items.RemoveAt(aboveItemIndex);
this.Options.Items.Insert(itemIndex, aboveItem);
}
对于向下按钮：
private void DownButton_Click(object sender, EventArgs e)
{
//this.Options is ListBox
if (this.Options.SelectedIndex == -1 ||
this.Options.SelectedIndex >= this.Options.Items.Count)
return;
string item, belowItem;
int itemIndex, belowItemIndex;
itemIndex = this.Options.SelectedIndex;
belowItemIndex = this.Options.SelectedIndex + 1;
if (belowItemIndex >= this.Options.Items.Count)
return;
item = (string)this.Options.Items[itemIndex];
belowItem = (string)this.Options.Items[belowItemIndex];
this.Options.Items.RemoveAt(itemIndex);
this.Options.Items.Insert(belowItemIndex, item);
this.Options.SelectedIndex = belowItemIndex;
}
【讨论】：
我将此用于多项选择。 它也适用于交错选择。
private void Order_buttons_Click(object sender, EventArgs e)
{
//If noselection return
if (Layouts_listBox.SelectedItems.Count == 0) return;
//Determines wether up or down
int movement = (sender as Button) == Order_Upbutton? - 1 : 1;
//creates a dictionary associating the original Index (ListBox) to the text
Dictionary<int, string> Items = new Dictionary<int, string>();
//Also creates a list with the Index for sorting
List<int> DesiredOrder = new List<int>();
//Cycle through the selection and fill both the list and dictionary
ListBox.SelectedObjectCollection NN = Layouts_listBox.SelectedItems;
foreach (object n in NN)
{
DesiredOrder.Add(Layouts_listBox.Items.IndexOf(n));
Items.Add(Layouts_listBox.Items.IndexOf(n), (string)n);
}
//Sort the List according to the desired button (Up or Down)
DesiredOrder.Sort();
if ((sender as Button) != Order_Upbutton) DesiredOrder.Reverse();
//I'm using this ErrorHandling but thats up to you
try
{
//Call the MoveItem (Credits to Save) according to the sorted order
foreach (int n in DesiredOrder) MoveItem(movement, Items[n]);
}
catch (Exception)
{
SystemSounds.Asterisk.Play();
}
}
public void MoveItem(int direction, string Selected)
{
// Checking selected item
if (!Layouts_listBox.Items.Contains(Selected) || Layouts_listBox.Items.IndexOf(Selected) < 0)
throw new System.Exception(); // No selected item - Cancel entire Func
// Calculate new index using move direction
int newIndex = Layouts_listBox.Items.IndexOf(Selected) + direction;
// Checking bounds of the range
if (newIndex < 0 || newIndex >= Layouts_listBox.Items.Count)
throw new System.Exception(); // Index out of range - Cancel entire Func
object selected = Layouts_listBox.Items[Layouts_listBox.Items.IndexOf(Selected)];
// Removing removable element
Layouts_listBox.Items.Remove(selected);
// Insert it in new position
Layouts_listBox.Items.Insert(newIndex, selected);
// Restore selection
Layouts_listBox.SetSelected(newIndex, true);
}
【讨论】：