java.lang.NullPointerException空指针错误!在线等!

显示全部楼层 · 2008-12-3 11:51:54

package LoginPageBean;
import java.util.List;
import javax.faces.application.Application;
import javax.faces.component.html.HtmlCommandButton;
import javax.faces.component.html.HtmlPanelGrid;
import javax.faces.context.FacesContext;
public class LoginBean {

private String username;
private String password;
private String loginmode;
private String ButtonArray[];
private HtmlPanelGrid ButtonGrid;
public String[] getButtonArray() {
return ButtonArray;
}
public void setButtonArray(String[] buttonArray) {
this.ButtonArray = buttonArray;
}
public HtmlPanelGrid getButtonGrid() {
return ButtonGrid;
}
public void setButtonGrid(HtmlPanelGrid buttonGrid) {
this.ButtonGrid = buttonGrid;
}
public String getUsername() {
return username;
}
public void setUsername(String username) {
this.username = username;
}
public String getPassword() {
return password;
}
public void setPassword(String password) {
this.password = password;
}
public String getLoginmode() {
return loginmode;
}
public void setLoginmode(String loginmode) {
this.loginmode = loginmode;
}
public void resetArray()
{
if(loginmode.equals("Teacher"))
{
ButtonArray[0]="1";
ButtonArray[1]="2";
ButtonArray[3]="3";

}
if(loginmode.equals("Admin"))
{
ButtonArray[0]="3";
ButtonArray[1]="2";
ButtonArray[2]="1";
}
}
public String resetButton()
{
resetArray();
Application application = FacesContext.getCurrentInstance().getApplication();
List children = ButtonGrid.getChildren();
children.clear();
for(int x=0;x<=ButtonArray.length;x++)
{
HtmlCommandButton button = (HtmlCommandButton)application.createComponent(HtmlCommandButton.COMPONENT_TYPE);
button.setValue(" "+ButtonArray[x]+" ");
children.add(button);
}
return loginmode;
}
我怀疑空指针就是出现在那个loginmode上.这个变量是根据登录界面Select下拉菜单所选的值点击登录按钮之后才被赋值的.

千问 · 2008-12-3 11:51:54

把有equals 判断的地方改为if(loginmode!=null&&loginmode.equals("Admin"))试试 ...要有这种习惯...

千问 · 2008-12-3 11:51:54

huaqiangzhao - 说得对，多用他那种方法。...

千问 · 2008-12-3 11:51:54

根据具体的错误，在后台打几个断点看看~~ 就可以找到错误了...