Question

我有一个活动，已经制作了片段。在我的活动中，当我点击登录按钮时，加载器将显示。加载器变得不可见之后，我只需要附加该片段。该片段已在其他一些类中创建。我只需要在circular loader变得不可见时附加该片段，并且我的片段已经在其他类中创建了，但我需要附加该片段。

MainActivity.java

handler = new Handler();
runnable = new Runnable() {
    @Override
    public void run() {
        if (loader_fragment != null) {
            AVLoadingIndicatorView loader = loader_fragment.getView().findViewById(R.id.loder_login);
            loader.setVisibility(View.INVISIBLE);
            timer.cancel();
        }

        Home_Screen home_screen = (Home_Screen) getFragmentManager().findFragmentById(R.id.Home_screen_fragment);
        fragmentManager1 = getFragmentManager();
        fragmentTransaction1 = fragmentManager1.beginTransaction();
        fragmentTransaction1.setCustomAnimations(
                R.animator.slide_in_left,
                R.animator.slide_out_left,
                R.animator.slide_in_right,
                R.animator.slide_out_right);
        Home_screen_student home_screen_student = new Home_screen_student();
        fragmentTransaction1.attach(R.id.Home_screen_fragment, home_screen_student);
        fragmentTransaction1.commit();
    }
};

HomeScreenFragment.java

package com.example.user.attendance;

import android.app.AlertDialog;
import android.app.Fragment;
import android.app.FragmentManager;
import android.app.FragmentTransaction;
import android.content.Intent;
import android.graphics.Color;
import android.graphics.drawable.ColorDrawable;
import android.os.Bundle;
import android.support.annotation.NonNull;
import android.support.design.widget.NavigationView;
import android.support.design.widget.NavigationView.OnNavigationItemSelectedListener;
import android.support.design.widget.Snackbar;
import android.support.v4.view.GravityCompat;
import android.support.v4.widget.DrawerLayout;
import android.support.v7.app.ActionBarDrawerToggle;
import android.support.v7.app.AppCompatActivity;
import android.view.LayoutInflater;
import android.view.MenuItem;
import android.view.View;
import android.view.ViewGroup;
import android.widget.Button;
import android.widget.Toast;


public class Home_Screen extends Fragment implements OnNavigationItemSelectedListener {
    DrawerLayout navigation_drawer;
    NavigationView navigationView;
    Button logout_Yes_button,logout_no_button, home_screen_take_attendance_button;

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {

        // Inflate the layout for this fragment
        View Home_screen = inflater.inflate(R.layout.navigation_drawer,container,false);
        android.support.v7.widget.Toolbar toolbar =
                (android.support.v7.widget.Toolbar) Home_screen.findViewById(R.id.custom_action_bar);
        ((AppCompatActivity) getActivity()).setSupportActionBar(toolbar);
        navigation_drawer = (DrawerLayout) Home_screen.findViewById(R.id.drawer_layout);
        navigationView = (NavigationView) Home_screen.findViewById(R.id.Navigation_view_for_teacher);

Logcat错误：

04-22 18:45:31.966 26404-26404 /？ E / Zygote：没有v2 04-22 18:45:54.221 26404-26404 / com.example.user.attendance E / AndroidRuntime：FATAL EXCEPTION：main 处理：com.example.user.attendance，PID：26404 java.lang.NullPointerException：尝试写入字段＆＃39; android.app.FragmentManagerImpl android.app.Fragment.mFragmentManager＆＃39;在null对象引用上在android.app.BackStackRecord.doAddOp（BackStackRecord.java:461）在android.app.BackStackRecord.replace（BackStackRecord.java:496）在android.app.BackStackRecord.replace（BackStackRecord.java:488） at com.example.user.attendance.MainActivity $ 3 $ 2.run（MainActivity.java:181）在android.os.Handler.handleCallback（Handler.java:739）在android.os.Handler.dispatchMessage（Handler.java:95）在android.os.Looper.loop（Looper.java:148）在android.app.ActivityThread.main（ActivityThread.java:7402） at java.lang.reflect.Method.invoke（Native Method）在com.android.internal.os.ZygoteInit $ MethodAndArgsCaller.run（ZygoteInit.java:1230）在com.android.internal.os.ZygoteInit.main（ZygoteInit.java:1120）

帮助我。

Answer 1

您在活动中使用viewPager吗？您可能需要从一个活动处理到另一个活动试试这个预告片：

  ViewPager viewPager = (ViewPager) findViewById(R.id.rew1);
  viewPager.setAdapter(new CustomPagerAdapter(this));
  TabLayout tabLayout = (TabLayout) findViewById(R.id.tabs);

  viewPager.addOnPageChangeListener(new TabLayout.TabLayoutOnPageChangeListener(tabLayout));
  tabLayout.addOnTabSelectedListener(new TabLayout.ViewPagerOnTabSelectedListener(viewPager));

//

 public enum CustomPagerEnum {

        HomeFragment (R.string.tab_text_1, R.layout.Home_screen_fragment),

        private int mTitleResId;
        private int mLayoutResId;

        CustomPagerEnum(int titleResId, int layoutResId) {
            mTitleResId = titleResId;
            mLayoutResId = layoutResId;
        }

        public int getTitleResId() {
            return mTitleResId;
        }

        public int getLayoutResId() {
            return mLayoutResId;
        }
    }

//

public class CustomPagerAdapter extends PagerAdapter {

    private Context mContext;

    public CustomPagerAdapter(Context context) {
        mContext = context;
    }

    @Override
    public Object instantiateItem(ViewGroup collection, int position) {
        home.CustomPagerEnum customPagerEnum = home.CustomPagerEnum.values()[position];
        LayoutInflater inflater = LayoutInflater.from(mContext);
        ViewGroup layout = (ViewGroup) inflater.inflate(customPagerEnum.getLayoutResId(), collection, false);
        collection.addView(layout);
        return layout;
    }

    @Override
    public void destroyItem(ViewGroup collection, int position, Object view) {
        collection.removeView((View) view);
    }

    @Override
    public int getCount() {
        return home.CustomPagerEnum.values().length;
    }

    @Override
    public boolean isViewFromObject(View view, Object object) {
        return view == object;
    }

    @Override
    public CharSequence getPageTitle(int position) {
        home.CustomPagerEnum customPagerEnum = home.CustomPagerEnum.values()[position];
        return mContext.getString(customPagerEnum.getTitleResId());
    }

}


My language is German but I hope I understand your problem well!

从活动中连接片段

1 个答案: