Question

我尝试使用ViewPager创建登录。

问题是当我在FragmentAccount中按下Login时会转到FragmentPage，但FragmentPage中的信息不会更新。

（我的理论）对我来说，感觉就像加载FragmentAccount时它还预加载FragmentPage，因此当它加载页面时它使用FragmentPage的非更新信息。虽然，我对Android Studio不太了解......

我认为问题出在前两个类中，但为了以防万一我添加了其他两个。

我非常了解帮助。

我做了测试，数据存储正确。

用户输入登录详细信息并按下登录按钮：

public class FragmentAccount extends Fragment implements View.OnClickListener {

    private static final String TAG = "FragmentAccount";

    private EditText fieldUsername;
    private EditText fieldPassword;
    private Button bLogIn;

    @Override
    public View onCreateView(LayoutInflater inflater, @Nullable ViewGroup container, Bundle savedInstanceState) {
        final View view = inflater.inflate(R.layout.fragment_account, container, false);

        fieldUsername = (EditText) view.findViewById(R.id.fragment_account_field_username);
        fieldPassword = (EditText) view.findViewById(R.id.fragment_account_field_password);

        bLogIn = (Button) view.findViewById(R.id.fragment_account_button_login);
        bLogIn.setOnClickListener(this);
        return view;
    }

    @Override
    public void onClick(View view) {
        boolean logedIn = MainActivity.user.logIn(fieldUsername.getText().toString(), fieldPassword.getText().toString());
        fieldPassword.setText("");
        if (logedIn) {
            fieldUsername.setText("");
            ((MainActivity) getActivity()).setViewPager(5);
        }
    }
}

登录详情应显示在此处：

public class FragmentProfile extends Fragment {

    private static final String TAG = "FragmentProfile";

    @Nullable
    @Override
    public View onCreateView(LayoutInflater inflater, @Nullable ViewGroup container, Bundle savedInstanceState) {
        View view = inflater.inflate(R.layout.fragment_profile, container, false);

        final TextView usernameText = (TextView) view.findViewById(R.id.fragment_profile_text_username_2);
        final TextView passwordText = (TextView) view.findViewById(R.id.fragment_profile_text_password_2);
        final Button bLogOut = (Button) view.findViewById(R.id.fragment_profile_button_logout);

        String s1 = MainActivity.user.getLogedInUsername();
        String s2 = MainActivity.user.getLogedInPassword();

        usernameText.setText(s1);
        passwordText.setText(s2);

        Log.i(TAG, s1 + ", " + s2);

        bLogOut.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                MainActivity.user.logOut();
                ((MainActivity) getActivity()).setViewPager(4);
            }
        });

        return view;
    }
}

存储登录数据的位置：

public class Users {

    private static final String TAG = "Users";

    private boolean isUserLogedIn = false;
    private String logedInUsername = "";
    private String loggedInPassword = "";

    final private String adminUsername = "1";
    final private String adminPassword = "2";

    public Users(){

    }

    public boolean logIn(String usr, String pass){
        if( usr.equals(adminUsername) && pass.equals(adminPassword)){
            isUserLogedIn = true;
            logedInUsername = usr;
            loggedInPassword = pass;

            Log.i(TAG, logedInUsername + ", " + loggedInPassword);
            return isUserLogedIn;
        }else{
            return isUserLogedIn;
        }
    }

    public void logOut(){
        isUserLogedIn = false;
        logedInUsername = "";
        loggedInPassword = "";
    }

    public boolean isUserLogedIn(){
        return isUserLogedIn;
    }

    public String getLogedInUsername(){
        return logedInUsername;
    }

    public String getLogedInPassword(){
        return loggedInPassword;
    }
}

主要活动，以及我在页面之间切换的地方

public class MainActivity extends AppCompatActivity implements NavigationView.OnNavigationItemSelectedListener{

    static final public Users user = new Users();
    private SectionsStatePageAdapter mSectionsStagePageAdapter;
    private ViewPager mViewPager;

    private DrawerLayout mDrawerLayout;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        //body
        mSectionsStagePageAdapter = new SectionsStatePageAdapter(getSupportFragmentManager());
        mViewPager = (ViewPager) findViewById(R.id.container);

        setupViewPager(mViewPager);

        //sidebar
        mDrawerLayout = (DrawerLayout) findViewById(R.id.drawerLayout);
        setNavigationListner();
    }

    private void setNavigationListner(){
        NavigationView mNavigationview = (NavigationView) findViewById(R.id.nav_view);
        mNavigationview.setNavigationItemSelectedListener(this);
    }

    /**
     * Add all of the fragment to the adapter, so we can change the fragment that is displayed.
     *
     * @param viewPager
     */
    private void setupViewPager(ViewPager viewPager){
        SectionsStatePageAdapter adapter = new SectionsStatePageAdapter(getSupportFragmentManager());
        adapter.addFragment(new FragmentDictionary(), "FragmentDictionary"); //0
        adapter.addFragment(new FragmentCheck(), "FragmentCheck"); //1
        adapter.addFragment(new FragmentHome(), "FragmentHome");//2
        adapter.addFragment(new FragmentPricetag(), "FragmentPricetag");//3
        adapter.addFragment(new FragmentAccount(), "FragmentAccount");//4
        adapter.addFragment(new FragmentProfile(), "FragmentProfile"); //5
        adapter.addFragment(new FragmentHelp(), "FragmentHelp");//7
        adapter.addFragment(new FragmentSettings(), "FragmentSettings");//8
        adapter.addFragment(new FragmentAboutUs(), "FragmentAboutUs");//9
        viewPager.setAdapter(adapter);
        setViewPager(2);
    }

    /**
     * Changes the fragment by passing the corresponding i to the fragment in the adapter
     * @param fragmentNumber
     */
    public void setViewPager(int fragmentNumber){
        mViewPager.setCurrentItem(fragmentNumber);
    }

    public void setmDrawerLayoutVisable(boolean setVisible){
        if(setVisible){
            mDrawerLayout.openDrawer(Gravity.RIGHT);
        }else{
            mDrawerLayout.closeDrawer(Gravity.RIGHT);
        }
    }

    @Override
    public boolean onNavigationItemSelected(@NonNull MenuItem item) {

        switch(item.getItemId()){
            case R.id.nav_account:
                if(user.isUserLogedIn()){
                    setViewPager(5);
                }else{
                    setViewPager(4);
                }
                setmDrawerLayoutVisable(false);
                break;
            case R.id.nav_help:
                setViewPager(7);
                setmDrawerLayoutVisable(false);
                break;
            case R.id.nav_settings:
                setViewPager(8);
                setmDrawerLayoutVisable(false);
                break;
            case R.id.nav_about_us:
                setViewPager(9);
                setmDrawerLayoutVisable(false);
                break;
            default:
                break;
        }

        return false;
    }
}

Answer 1

你的理论确实是正确的。

默认情况下，ViewPager会加载2个额外页面，前一页和后一页。不幸的是，这也是屏幕外页面的最小限制。

您必须实现这些片段相互通信的方式，EventBus或其他方法。

片段未更新

1 个答案: