Question

这是我的代码

  package com.saverx.rushabh.saverx;

import android.support.v4.app.Fragment;
import android.support.v4.app.FragmentManager;
import android.support.v4.app.FragmentPagerAdapter;
import android.support.v4.view.ViewPager;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.util.Log;
import android.view.LayoutInflater;
import android.view.View;
import android.os.Bundle;
import android.support.design.widget.TabLayout;
import android.view.ViewGroup;


public class MainActivity extends AppCompatActivity {


    View view;
    private static final String ARG_SECTION_NUMBER = "section_number";
    ViewPager viewPager;
    //TabLayout tabLayout;
    TabLayout tabLayout;
    LayoutInflater inflater;
    ViewGroup container;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
         this.container=container;
         this.inflater=inflater;
        this.view= inflater.inflate(R.layout.activity_main, container, false);
        viewPager=(ViewPager)view.findViewById(R.id.viewPager);
        viewPager.setAdapter(new sliderAapter(getSupportFragmentManager()));
        tabLayout=(TabLayout)view.findViewById(R.id.sliding_tab);
        tabLayout.post(new Runnable() {
            @Override
            public void run() {
                tabLayout.setupWithViewPager(viewPager);
            }
        });








        //return view;
    }

    private class sliderAapter extends FragmentPagerAdapter {


        public sliderAapter(FragmentManager supportFragmentManager) {
            super(supportFragmentManager);
        }

        @Override
        public Fragment getItem(int position) {
            Log.e("adapter", ""+position);
            //  return new CalendarFragment();
            NewLeadsFragment obj= new NewLeadsFragment();
          /*  Bundle bundle=new Bundle();
            bundle.putInt("position",position);
            obj.setArguments(bundle);
            return obj;*/
          return obj;

        }

        @Override
        public int getCount() {
            return 3;// 3 tabs
        }


        @Override
        public CharSequence getPageTitle(int position) {
            switch (position) {
                case 0:
                    return "Leads";
                case 1:
                    return "Meetings";
                case 2:
                    return "Service";
            }
            return null;
        }

    }



}

例外是

  Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'android.view.View android.view.LayoutInflater.inflate(int, android.view.ViewGroup, boolean)' on a null object reference
                                                       at com.saverx.rushabh.saverx.MainActivity.onCreate(MainActivity.java:33)

当我使用片段实例活动

时，此代码工作正常

我正在使用tablayout，以便我可以拖动注册并使用tablayout登录。

运行时错误是：

java.lang.RuntimeException：无法启动活动ComponentInfo {com.saverx.rushabh.saverx / com.saverx.rushabh.saverx.MainActivity}：java.lang.NullPointerException：尝试调用虚方法'android.view。在空对象引用上查看android.view.LayoutInflater.inflate（int，android.view.ViewGroup，boolean）'

我总结一下，错误可能是由于我没有插入this.view=view但是它抛出同样的异常

Answer 1

onCreate活动中没有容器和inflater。您可能已将片段onCreateView中的代码复制到activity onCreate。检查这些行。：

this.container=container;
this.inflater=inflater;
this.view= inflater.inflate(R.layout.activity_main, container, false);

我在Activity中使用TabLaout，但它显示NULL指针

1 个答案: