Java 无法正确实现布尔逻辑
以下是我试图实现的目标: 我有ActioBar,我有一个菜单项,名为Login,在ActionBar上。单击此登录菜单项时,它会在actionbar中添加一个新选项卡,并在父活动的容器中加载带有login_布局的片段。如果单击除login选项卡之外的任何其他选项卡,则login选项卡将消失。只有再次单击login菜单项时,它才能重新出现。 登录成功后,我想将菜单项的标题更改为“注销”。现在,在将登录菜单项的标题设置为“注销”后,如果我单击它,则不应在活动栏上添加任何选项卡,因为用户已登录 我有一个工作代码,直到用户成功登录的部分,因此登录菜单项的标题已更改为注销。但我遇到的问题是,现在当用户单击注销时,它仍然添加选项卡并显示登录片段 这样做的简单方法是使用menuItem.getTitle()并根据menuItem的当前标题限制操作。但我认为这不是实现这一点的好方法。因此,现在我尝试使用标志“LoginMemItemFlag”并试图解决这个问题,但没有成功。我已经能够使它工作到一点,它改变了登录菜单项的标题,以注销,但当用户点击注销它添加/显示登录标签再次,这是我不想要的。谁能告诉我我做错了什么,并指出我在正确的方向。谢谢 下面是我创建菜单项并添加选项卡、删除选项卡、更改标志以及基于标志值更改菜单项标题的类的代码:Java 无法正确实现布尔逻辑,java,android,boolean,boolean-logic,Java,Android,Boolean,Boolean Logic,以下是我试图实现的目标: 我有ActioBar,我有一个菜单项,名为Login,在ActionBar上。单击此登录菜单项时,它会在actionbar中添加一个新选项卡,并在父活动的容器中加载带有login_布局的片段。如果单击除login选项卡之外的任何其他选项卡,则login选项卡将消失。只有再次单击login菜单项时,它才能重新出现。 登录成功后,我想将菜单项的标题更改为“注销”。现在,在将登录菜单项的标题设置为“注销”后,如果我单击它,则不应在活动栏上添加任何选项卡,因为用户已登录 我有一
public class HomeActivity extends SherlockFragmentActivity {
String mCurFilter;
static boolean flag,loginMenuItemFlag;
LoginScreenFragment loginFragment;
HomeFragment homeFragment;
CartFragment cartFragment;
MyFragment myFragment;
FragmentTransaction ft, ft2;
ActionBar actionbar;
MenuItem loginItem;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.home);
// ActionBar
actionbar = getSupportActionBar();
actionbar.setNavigationMode(ActionBar.NAVIGATION_MODE_TABS);
homeFragment = new HomeFragment();
cartFragment = new CartFragment();
myFragment = new MyFragment();
loginFragment = new LoginScreenFragment();
actionbar.addTab(actionbar.newTab()
.setText(R.string.home_fragment_title)
.setTabListener(new MyTabsListener(homeFragment))
.setTag("HOME"));
actionbar.addTab(actionbar.newTab()
.setText(R.string.cart_fragment_title)
.setTabListener(new MyTabsListener(cartFragment))
.setTag("CART"));
actionbar.addTab(actionbar.newTab()
.setText(R.string.my_fragment_title)
.setTabListener(new MyTabsListener(myFragment))
.setTag("MYFragment"));
if (!flag) {
ft = getSupportFragmentManager().beginTransaction();
ft.add(R.id.fragment_container, homeFragment);
ft.show(homeFragment);
ft.add(R.id.fragment_container, cartFragment);
ft.hide(cartFragment);
ft.add(R.id.fragment_container, myFragment);
ft.hide(myFragment);
ft.add(R.id.fragment_container, loginFragment);
ft.hide(loginFragment);
ft.commit();
flag = true;
} else {
}
}
@Override
protected void onSaveInstanceState(Bundle outState) {
super.onSaveInstanceState(outState);
outState.putInt("tab", getSupportActionBar()
.getSelectedNavigationIndex());
}
@Override
public boolean onCreateOptionsMenu(final Menu menu) {
loginItem = menu.add(R.string.menuitem_login);
loginItem.setTitle(R.string.menuitem_login);
loginItem.setShowAsAction(MenuItem.SHOW_AS_ACTION_ALWAYS);
loginItem.setOnMenuItemClickListener(new OnMenuItemClickListener() {
@Override
public boolean onMenuItemClick(MenuItem item) {
if(!loginMenuItemFlag){
Tab loginTab = actionbar.newTab()
.setText(R.string.login_fragment_title)
.setTabListener(new MyTabsListener(loginFragment))
.setTag(R.string.login_label);
actionbar.addTab(loginTab);
actionbar.selectTab(loginTab);
loginItem.setVisible(false);
loginItem.setTitle(R.string.login_label);
//loginMenuItemFlag = false;
}
else{
loginItem.setTitle(R.string.menuitem_login);
//loginMenuItemFlag = false;
}
return false;
}
});
return true;
}
// removes TAB at a specified position
public void deleteTabAt(int tabPosition) {
actionbar = getSupportActionBar();
actionbar.removeTabAt(tabPosition);
}
//setting Login menu Item to visible when Login tab has been removed from the tabs
public void setLoginMenuItemVisible() {
loginItem.setVisible(true);
}
public void changeLoginMenuFlag(){
loginMenuItemFlag = false;
}
//chaging Log In menu item to Log out upon successful Log in
public void changeLoginMenutItem(){
if(!loginMenuItemFlag){
loginItem.setTitle(R.string.menuitem_logout);
loginMenuItemFlag = false;
}else{
loginItem.setTitle(R.string.menuitem_login);
loginMenuItemFlag= true;
}
}
class MyTabsListener implements ActionBar.TabListener {
public SherlockFragment fragment;
public MyTabsListener(SherlockFragment fragment) {
this.fragment = fragment;
}
@Override
public void onTabReselected(Tab tab, FragmentTransaction ft) {
System.out.println("TabReselected " + tab.getPosition());
}
@Override
public void onTabSelected(Tab tab, FragmentTransaction ft) {
System.out.println("TabSelected " + tab.getPosition());
ft.show(this.fragment);
}
@Override
public void onTabUnselected(Tab tab, FragmentTransaction ft) {
System.out.println("TabUnselected " + tab.getPosition());
ft.hide(this.fragment);
//making check if the unselected tab was Login tab(located at tab position 3),if it was a login tab than we remove it from ActionBar
if (tab.getPosition() == 3) {
deleteTabAt(tab.getPosition());
setLoginMenuItemVisible();
}
}
}
}
下面是执行登录操作的LoginFragment中的代码。下面是在尝试登录后执行的代码片段
@Override
public void sendResponse(String response) {
pd.dismiss();
System.out.println("Response in the callback: " + response);
if (response != null) {
FragmentActivity homeActivity = getActivity();
if (homeActivity instanceof HomeActivity) {
((HomeActivity) homeActivity).deleteTabAt(3);
((HomeActivity) homeActivity).changeLoginMenuFlag();
((HomeActivity) homeActivity).changeLoginMenutItem();
((HomeActivity) homeActivity).setLoginMenuItemVisible();
Toast.makeText(getActivity(), "Login Successful!",
Toast.LENGTH_LONG).show();
}
} else {
Toast.makeText(getActivity(), "Login failed,Please try again...",
Toast.LENGTH_LONG).show();
}
}
谢谢。使用
onPrepareOptionsMenu()
更改菜单,使用onoptionsinesselected
处理菜单项单击:
private boolean mLoggedIn;
private MenuItem mItemLogIn;
private MenuItem mItemLogOut;
@Override
public boolean onCreateOptionsMenu(Menu menu) {
mItemLogIn = menu.add("Log In");
mItemLogOut = menu.add("Log Out");
//---set more properties--
return super.onCreateOptionsMenu(menu);
}
@Override
public boolean onPrepareOptionsMenu(Menu menu) {
mItemLogIn.setVisible(!mLoggedIn);
mItemLogOut.setVisible(mLoggedIn);
return super.onPrepareOptionsMenu(menu);
}
@Override
public boolean onOptionsItemSelected(MenuItem item) {
if(item.equals(mItemLogIn)){
//--login--
mLoggedIn = true;
invalidateOptionsMenu();
}else if(item.equals(mItemLogOut)){
//--log out--
mLoggedIn = false;
invalidateOptionsMenu();
}
return super.onOptionsItemSelected(item);
}