关于SWT中LIST控件的问题

Question

我的程序如下： 
package hj.com; import org.eclipse.swt.SWT; 
import org.eclipse.swt.events.KeyAdapter; 
import org.eclipse.swt.events.KeyEvent; 
import org.eclipse.swt.events.KeyListener; 
import org.eclipse.swt.widgets.Display; 
import org.eclipse.swt.widgets.List; 
import org.eclipse.swt.widgets.Shell; public class testList { protected Shell shell; /** 
 * Launch the application 
 * @param args 
 */ 
public static void main(String[] args) { 
try { 
testList window = new testList(); 
window.open(); 
} catch (Exception e) { 
e.printStackTrace(); 
} 
} /** 
 * Open the window 
 */ 
public void open() { 
final Display display = Display.getDefault(); 
createContents(); 
shell.open(); 
shell.layout(); 
while (!shell.isDisposed()) { 
if (!display.readAndDispatch()) 
display.sleep(); 
} 
} /** 
 * Create contents of the window 
 */ 
protected void createContents() { 
shell = new Shell(); 
shell.setSize(500, 375); 
shell.setText("SWT Application"); final List list=new List(shell,SWT.BORDER); 
// list.select(0); 
list.setItems(new String[]{"第0","第1","第2","第3","第4"}); 
list.setBounds(0,0,50,200); 
list.setSelection(0); list.addKeyListener(new KeyAdapter(){ 
        public void keyPressed(KeyEvent e){ 
         int curIndex=list.getSelectionIndex(); 
         int total=list.getItemCount(); 
         
         if(e.keyCode==SWT.ARROW_UP){ 
         if(curIndex==0){ 
         list.select(total-1); 
         int c=list.getSelectionIndex(); 
         System.out.println(c); 
         } 
         }else if(e.keyCode==SWT.ARROW_DOWN){ 
         if(curIndex==total-1){ 
         list.select(0); 
         int c=list.getSelectionIndex(); 
         System.out.println(c); 
         } 
         } 
        } }); // 
} } 
我的功能是当按光标向下时，LISH中被选中的item依次下移，但是当移到最后一项时，则重新选择第一项。但上述程序当移动到最后一项，却选择第二项而不是第一项，这是为什么呢？？

Answer 1

package test.swing; import org.eclipse.swt.SWT; 
import org.eclipse.swt.events.KeyAdapter; 
import org.eclipse.swt.events.KeyEvent; 
import org.eclipse.swt.events.KeyListener; 
import org.eclipse.swt.widgets.Display; 
import org.eclipse.swt.widgets.List; 
import org.eclipse.swt.widgets.Shell; public class TestList { 
  protected Shell shell;   /** 
   * Launch the application 
   *  
   * @param args 
   */ 
  public static void main(String[] args) { 
    try { 
      TestList window = new TestList(); 
      window.open(); 
    } catch (Exception e) { 
      e.printStackTrace(); 
    } 
  }   /** 
   * Open the window 
   */ 
  public void open() { 
    final Display display = Display.getDefault(); 
    createContents(); 
    shell.open(); 
    shell.layout(); 
    while (!shell.isDisposed()) { 
      if (!display.readAndDispatch()) 
        display.sleep(); 
    } 
  }   /** 
   * Create contents of the window 
   */ 
  protected void createContents() { 
    shell = new Shell(); 
    shell.setSize(500, 375); 
    shell.setText("SWT Application"); 
    final List list = new List(shell, SWT.BORDER | SWT.V_SCROLL); 
    // list.select(0); 
    list.setItems(new String[] { "第0", "第1", "第2", "第3", "第4" }); 
    list.setBounds(0, 0, 50, 200); 
    list.setSelection(0); 
    list.addKeyListener(new KeyAdapter() { 
      int lastIndex = -1;       public void keyReleased(KeyEvent e) { 
        int curIndex = list.getSelectionIndex(); 
        System.out.println("c=" + curIndex); 
        int total = list.getItemCount(); 
        if (e.keyCode == SWT.ARROW_UP) { 
          if (lastIndex == 0) { 
            list.select(total - 1); 
            curIndex = total-1; 
            list.showSelection(); 
            int c = list.getSelectionIndex(); 
            System.out.println(c); 
          } 
        } else if (e.keyCode == SWT.ARROW_DOWN) { 
          if (lastIndex == total - 1) { 
            list.select(0); 
            curIndex = 0; 
            list.showSelection(); 
            int c = list.getSelectionIndex(); 
            System.out.println(c); 
          } 
        } 
        lastIndex = curIndex; 
      } 
    }); 
    //   
  } 
}