如何将fragment和AppCompatActivity都扩展到同一类? [英] How to extend both fragment and AppCompatActivity to a same class?
问题描述
我有一个类.我将Fragment扩展到了这个类,因为我在开发Navigation Drawer时使用了片段.
I have a class.I have extended Fragment to this class because I used fragments when developing Navigation Drawer.
代码在下面
public class aboutSLFragment extends Fragment {
public aboutSLFragment() {
// Required empty public constructor
}
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
// Inflate the layout for this fragment
return inflater.inflate(R.layout.fragment_about_sl, container, false);
}
@Override
public void onViewCreated(View view, @Nullable Bundle savedInstanceState) {
super.onViewCreated(view, savedInstanceState);
//you can set the title for your toolbar here for different fragments different titles
getActivity().setTitle("About Sri Lanka");
}
}
现在我想向该类添加一个图像滑块.我使用的代码是这个.
Now I want to add a image slider to that class.The code I used is this.
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
viewPager = (ViewPager) findViewById(R.id.viewPager);
sliderDotspanel = (LinearLayout) findViewById(R.id.SliderDots);
ViewPagerAdapter viewPagerAdapter = new ViewPagerAdapter(this);
viewPager.setAdapter(viewPagerAdapter);
dotscount = viewPagerAdapter.getCount();
dots = new ImageView[dotscount];
for(int i = 0; i < dotscount; i++){
dots[i] = new ImageView(this);
dots[i].setImageDrawable(ContextCompat.getDrawable(getApplicationContext(), R.drawable.non_active_dot));
LinearLayout.LayoutParams params = new LinearLayout.LayoutParams(LinearLayout.LayoutParams.WRAP_CONTENT, LinearLayout.LayoutParams.WRAP_CONTENT);
params.setMargins(8, 0, 8, 0);
sliderDotspanel.addView(dots[i], params);
}
dots[0].setImageDrawable(ContextCompat.getDrawable(getApplicationContext(), R.drawable.active_dot));
viewPager.addOnPageChangeListener(new ViewPager.OnPageChangeListener() {
@Override
public void onPageScrolled(int position, float positionOffset, int positionOffsetPixels) {
}
@Override
public void onPageSelected(int position) {
for(int i = 0; i< dotscount; i++){
dots[i].setImageDrawable(ContextCompat.getDrawable(getApplicationContext(), R.drawable.non_active_dot));
}
dots[position].setImageDrawable(ContextCompat.getDrawable(getApplicationContext(), R.drawable.active_dot));
}
@Override
public void onPageScrollStateChanged(int state) {
}
});
}
当我将此图像滑块代码添加到aboutSLFragment类中时,代码将如下所示(如下)
When I add this image slider code to the aboutSLFragment class the code will be like this(below)
public class aboutSLFragment extends Fragment {
ViewPager viewPager;
LinearLayout sliderDotspanel;
private int dotscount;
private ImageView[] dots;
public aboutSLFragment() {
// Required empty public constructor
}
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
viewPager = (ViewPager) findViewById(R.id.viewPager);
sliderDotspanel = (LinearLayout) findViewById(R.id.SliderDots);
ViewPagerAdapter viewPagerAdapter = new ViewPagerAdapter(this);
viewPager.setAdapter(viewPagerAdapter);
dotscount = viewPagerAdapter.getCount();
dots = new ImageView[dotscount];
for(int i = 0; i < dotscount; i++){
dots[i] = new ImageView(this);
dots[i].setImageDrawable(ContextCompat.getDrawable(getApplicationContext(), R.drawable.non_active_dot));
LinearLayout.LayoutParams params = new LinearLayout.LayoutParams(LinearLayout.LayoutParams.WRAP_CONTENT, LinearLayout.LayoutParams.WRAP_CONTENT);
params.setMargins(8, 0, 8, 0);
sliderDotspanel.addView(dots[i], params);
}
dots[0].setImageDrawable(ContextCompat.getDrawable(getApplicationContext(), R.drawable.active_dot));
viewPager.addOnPageChangeListener(new ViewPager.OnPageChangeListener() {
@Override
public void onPageScrolled(int position, float positionOffset, int positionOffsetPixels) {
}
@Override
public void onPageSelected(int position) {
for(int i = 0; i< dotscount; i++){
dots[i].setImageDrawable(ContextCompat.getDrawable(getApplicationContext(), R.drawable.non_active_dot));
}
dots[position].setImageDrawable(ContextCompat.getDrawable(getApplicationContext(), R.drawable.active_dot));
}
@Override
public void onPageScrollStateChanged(int state) {
}
});
}
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
// Inflate the layout for this fragment
return inflater.inflate(R.layout.fragment_about_sl, container, false);
}
@Override
public void onViewCreated(View view, @Nullable Bundle savedInstanceState) {
super.onViewCreated(view, savedInstanceState);
//you can set the title for your toolbar here for different fragments different titles
getActivity().setTitle("About Sri Lanka");
}
}
但是这会带来很多错误.但是当我扩展AppCompatActivity类时,错误会消失,除了一个错误.像这样(如下)
But this gives a whole bunch of errors.But when I extend the AppCompatActivity class the errors disappear except for one.Like this(below)
public class aboutSLFragment extends Fragment, AppCompatActivity
据我所知我们不能继承两个类,那么我应该怎么做才能解决呢?请帮我?如果有人更正我的代码,将不胜感激.
As I know we can't inherit two classes.So what should I do to resolve it? please help me? It would be greatly appreciated if someone corrects my code.
我在aboutSLFragment.java中添加了一个图像滑块,但是有一些我无法修复的错误.我是android新手,所以请有人告诉我如何修复错误.我将这些错误加粗了.
I've added an image slider to aboutSLFragment.java but there are some errors which I cannot fix.I'm new to android so please somebody tell me how to fix the errors.I've bolded the errors.
public class aboutSLFragment extends Fragment{
ViewPager viewPager;
LinearLayout sliderDotspanel;
private int dotscount;
private ImageView[] dots;
public aboutSLFragment() {
// Required empty public constructor
}
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
viewPager = (ViewPager) **findViewById**(R.id.viewPager);
sliderDotspanel = (LinearLayout) **findViewById**(R.id.SliderDots);
ViewPagerAdapter viewPagerAdapter = new ViewPagerAdapter(**this**);
viewPager.setAdapter(viewPagerAdapter);
dotscount = viewPagerAdapter.getCount();
dots = new ImageView[dotscount];
for(int i = 0; i < dotscount; i++){
dots[i] = new ImageView(**this**);
dots[i].setImageDrawable(ContextCompat.getDrawable(**getApplicationContext()**, R.drawable.non_active_dot));
LinearLayout.LayoutParams params = new LinearLayout.LayoutParams(LinearLayout.LayoutParams.WRAP_CONTENT, LinearLayout.LayoutParams.WRAP_CONTENT);
params.setMargins(8, 0, 8, 0);
sliderDotspanel.addView(dots[i], params);
}
dots[0].setImageDrawable(ContextCompat.getDrawable(**getApplicationContext()**, R.drawable.active_dot));
viewPager.addOnPageChangeListener(new ViewPager.OnPageChangeListener() {
@Override
public void onPageScrolled(int position, float positionOffset, int positionOffsetPixels) {
}
@Override
public void onPageSelected(int position) {
for(int i = 0; i< dotscount; i++){
dots[i].setImageDrawable(ContextCompat.getDrawable(**getApplicationContext()**, R.drawable.non_active_dot));
}
dots[position].setImageDrawable(ContextCompat.getDrawable(**getApplicationContext()**, R.drawable.active_dot));
}
@Override
public void onPageScrollStateChanged(int state) {
}
});
// Inflate the layout for this fragment
return inflater.inflate(R.layout.fragment_about_sl, container, false);
}
@Override
public void onViewCreated(View view, @Nullable Bundle savedInstanceState) {
super.onViewCreated(view, savedInstanceState);
//you can set the title for your toolbar here for different fragments different titles
getActivity().setTitle("About Sri Lanka");
}
}
推荐答案
我更改了您的代码.问题是:
I have changed your code. Problem was:
-
findViewById()
.活动已经具有findViewById()
方法,因此您可以在活动"中调用它.但是Fragment
没有这种方法.在Fragment
中,您必须通过View.findViewById()
方法找到一个View,这里的View
将是您在中夸大的视图onCreateView()
-
新的ViewPagerAdapter(this)
.要创建一个视图,您必须提供一个活动上下文.在这里,您要传递this
的Fragment实例,而不是Activity Context -
ContextCompat.getDrawable()
此方法也需要一个Context.getApplicationContext()
在Fragment中不可用.您必须从Fragment调用getActivity()
或getContext()
来获取活动的上下文.
findViewById()
. Activity already havefindViewById()
method so you can call it in Activity. ButFragment
don't have this method. InFragment
you have to find a View byView.findViewById()
method, hereView
will be the view you are inflating inonCreateView()
new ViewPagerAdapter(this)
. To create a View you have to provide a Activity Context. Here you are passingthis
its your Fragment instance not Activity ContextContextCompat.getDrawable()
this method also takes a Context.getApplicationContext()
is not available in Fragment. You have to callgetActivity()
orgetContext()
from Fragment to get Context of the Activity.
public class aboutSLFragment extends Fragment{
ViewPager viewPager;
LinearLayout sliderDotspanel;
private int dotscount;
private ImageView[] dots;
public aboutSLFragment() {
// Required empty public constructor
}
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View rootView = inflater.inflate(R.layout.fragment_about_sl, container, false);
viewPager = (ViewPager) rootView .findViewById(R.id.viewPager);
sliderDotspanel = (LinearLayout)rootView.findViewById(R.id.SliderDots);
ViewPagerAdapter viewPagerAdapter = new ViewPagerAdapter(getContext());
viewPager.setAdapter(viewPagerAdapter);
dotscount = viewPagerAdapter.getCount();
dots = new ImageView[dotscount];
for(int i = 0; i < dotscount; i++){
dots[i] = new ImageView(getContext());
dots[i].setImageDrawable(ContextCompat.getDrawable(getContext(), R.drawable.non_active_dot));
LinearLayout.LayoutParams params = new LinearLayout.LayoutParams(LinearLayout.LayoutParams.WRAP_CONTENT, LinearLayout.LayoutParams.WRAP_CONTENT);
params.setMargins(8, 0, 8, 0);
sliderDotspanel.addView(dots[i], params);
}
dots[0].setImageDrawable(ContextCompat.getDrawable(getContext(), R.drawable.active_dot));
viewPager.addOnPageChangeListener(new ViewPager.OnPageChangeListener() {
@Override
public void onPageScrolled(int position, float positionOffset, int positionOffsetPixels) {
}
@Override
public void onPageSelected(int position) {
for(int i = 0; i< dotscount; i++){
dots[i].setImageDrawable(ContextCompat.getDrawable(getContext(), R.drawable.non_active_dot));
}
dots[position].setImageDrawable(ContextCompat.getDrawable(getContext(), R.drawable.active_dot));
}
@Override
public void onPageScrollStateChanged(int state) {
}
});
// Inflate the layout for this fragment
return rootView;
}
@Override
public void onViewCreated(View view, @Nullable Bundle savedInstanceState) {
super.onViewCreated(view, savedInstanceState);
//you can set the title for your toolbar here for different fragments different titles
getActivity().setTitle("About Sri Lanka");
}
}
检查此代码.
这篇关于如何将fragment和AppCompatActivity都扩展到同一类?的文章就介绍到这了,希望我们推荐的答案对大家有所帮助,也希望大家多多支持IT屋!