显示错误
致命异常：计时器0 流程：com.example.tanis.myapplication，PID：9918 java.lang.NullPointerException：尝试在空对象引用上调用虚拟方法“ void android.support.v4.app.FragmentActivity.runOnUiThread（java.lang.Runnable）” 在com.example.tanis.myapplication.MenuItems.Home $ Mytime.run（Home.java:158） 在java.util.TimerThread.mainLoop（Timer.java:555） 在java.util.TimerThread.run（Timer.java:505）
它向我显示了getActivity（）。runOnUiThread（new Runnable（）中的错误，我不知道为什么会出现该错误，请帮助 谢谢
package com.example.tanis.myapplication.MenuItems;
import android.content.Context;
import android.content.Intent;
import android.graphics.drawable.Drawable;
import android.os.Bundle;
import android.support.annotation.Nullable;
import android.support.design.widget.FloatingActionButton;
import android.support.v4.app.Fragment;
import android.support.v4.content.res.ResourcesCompat;
import android.support.v4.view.ViewPager;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.Button;
import android.widget.TextView;
import com.example.tanis.myapplication.Adapters.CardItemString;
import com.example.tanis.myapplication.Adapters.CardPagerAdapterS;
import com.example.tanis.myapplication.Adapters.ViewPagerAdapter;
import com.example.tanis.myapplication.R;
import com.example.tanis.myapplication.Services.website_designing;
import java.util.Timer;
import java.util.TimerTask;
public class Home extends Fragment {
ViewPager mViewPager;
CardPagerAdapterS mCardAdapter;
ShadowTransformer mCardShadowTransformer;
private Context context;
ViewPager viewPager;
String titlesText [] = {" Website Design", " Digital Marketing", " Domain Registration", "Graphics Design", " Mobile Apps", " Server Hosting",
" Software Development", " Content Marketing", " Security (SSl)"};
String detailsArray [] = {
"Your website is your digital home. We create, design, redesign, develop, improvise, and implement. We make beautiful websites",
"We help your business reach potential customers on every possible digital device through all possible media channels ",
"To launch your website the first thing you need is the domain name. You can choose your domain name with us here ",
"We generate creative solutions and can create a wide range of graphic for your clients which match their business ",
"We are mobile. And we make you mobile. We make responsive websites and mobile apps which compliment your business ",
"When you are hosting your website in the India you will benefit from a higher ping rate and lowest latency ",
"Our team is competent at coding web apps with keen attention to detail & intuitive functionality that is high on design & creativity",
"Content is the heart of your digital presence. We create the right content with the right focus for your business",
"Secure your site with the world's leading provider of online security and get these exclusive features at no added cost",
};
int[] images = {R.drawable.website_design, R.drawable.digita,R.drawable.domain_registration,R.drawable.gric,
R.drawable.mob,R.drawable.server,R.drawable.software_development,R.drawable.ontent,R.drawable.ssl};
private static final String KEY_MOVIE_TITLE = "key_title";
public Home() {
// Required empty public constructor
}
/**
* Use this factory method to create a new instance of
* this fragment.
*
* @return A new instance of fragment FragmentAction.
*/
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
}
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState)
{
View v = inflater.inflate(R.layout.home,container,false);
TextView txt = (TextView)v.findViewById( R.id.textView12 );
txt.setText("\u25BA Creative & Dedicated Team");
TextView txt1 = (TextView)v.findViewById( R.id.textView13 );
txt1.setText("\u25BA Affordable Cost");
TextView txt2 = (TextView)v.findViewById( R.id.textView14 );
txt2.setText("\u25BA Maintain Long Relationship");
TextView txt3 = (TextView)v.findViewById( R.id.textView15 );
txt3.setText("\u25BA Timely Deliverly ");
context = this.getContext();
Button b = (Button) v.findViewById( R.id.button7 ) ;
b.setOnClickListener( new View.OnClickListener() {
@Override
public void onClick(View view) {
Intent intent=new Intent( getActivity(), website_designing.class);
}
} );
mViewPager = (ViewPager)v.findViewById(R.id.viewpager1);
mCardAdapter = new CardPagerAdapterS();
for (int i=0; i<titlesText.length; i++){
mCardAdapter.addCardItemS(new CardItemString( titlesText[i], detailsArray[i],images[i]));
}
mCardShadowTransformer = new ShadowTransformer(mViewPager, mCardAdapter);
mViewPager.setAdapter(mCardAdapter);
mViewPager.setPageTransformer(false, mCardShadowTransformer);
mViewPager.setOffscreenPageLimit(3);
viewPager = (ViewPager)v.findViewById( R.id.viewpager );
ViewPagerAdapter viewPagerAdapter = new ViewPagerAdapter( this.getContext() );
viewPager.setAdapter( viewPagerAdapter );
Timer timer = new Timer( );
timer.scheduleAtFixedRate( new Mytime(),2000,4000 );
FloatingActionButton floatingActionButton = (FloatingActionButton)v.findViewById( R.id.floatingActionButton );
floatingActionButton.setOnClickListener( new View.OnClickListener() {
@Override
public void onClick(View view) {
startActivity( new Intent( getActivity(),Registration.class ) );
}
} );
return v;
}
public class Mytime extends TimerTask {
@Override
public void run() {
//here it is showing me error//
**getActivity().runOnUiThread( new Runnable() {
@Override
public void run() {
if(viewPager.getCurrentItem() == 0) {
viewPager.setCurrentItem( 1 );
}
else if (viewPager.getCurrentItem()== 1){
viewPager.setCurrentItem( 2 );
}
else if (viewPager.getCurrentItem()== 2){
viewPager.setCurrentItem( 3 );
}
else if (viewPager.getCurrentItem()== 3){
viewPager.setCurrentItem( 4 );
}
else {
viewPager.setCurrentItem(0);
}
}
} );
}
}
@Override
public void onViewCreated(View view, @Nullable Bundle savedInstanceState) {
super.onViewCreated(view, savedInstanceState);
}
}
答案 0 :(得分：1)
当应用程序尝试使用java.lang.NullPointerException：尝试调用虚拟方法'void android.support.v4.app.FragmentActivity.runOnUiThread（java.lang.Runnable）'
the boot documentation 具有空值的对象引用。
您应该在下面添加检查内容。
if (getActivity()!=null)
演示
if (getActivity()!=null)
{
getActivity().runOnUiThread( new Runnable() {
@Override
public void run() {
......
}
答案 1 :(得分：0)
将上下文传递给线程，如：
new Mytime( getActivity() );
现在在您的线程中，进行如下更改
public class Mytime extends TimerTask {
Context context;
public Mytime(Context _context){
context = _context;
}
@Override
public void run() {
context.runOnUiThread( new Runnable() {
............
答案 2 :(得分：0)
请勿在内部类中使用getActivity()。只需在片段中创建一个字段：
private Activity myActivity;
，然后在片段的onCreateView()中对其进行初始化，例如：
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState){
myActivity = getActivity();
//Your code
}
然后使用：
myActivity.runOnUiThread()
答案 3 :(得分：0)
您可以像下面的步骤
一样在Fragment中使用它
STEP -1
Activity mActivity;
@Override
public void onAttach(Context context) {
super.onAttach(context);
mActivity = (Activity) context;
}
STEP -2
public class Mytime extends TimerTask {
@Override
public void run() {
mActivity.runOnUiThread(new Runnable() {
@Override
public void run() {
// Your code here
}
});
}
}