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Poll
Apps on a null object reference
- By Kurniawan
- Android Development
- 5 Replies
Excuseme.. i hava promblem with my activity. how i fix on a null object reference. Thanks 
This My MainActivity.java
This FragmentSlider.java
This SliderIndicator.java
SliderPagerAdapter.java
SliderView.java
Code:
E/AndroidRuntime: FATAL EXCEPTION: main
Process: com.yk.danaberkah, PID: 22728
java.lang.RuntimeException: Unable to start activity ComponentInfo{com.yk.danaberkah/com.yk.danaberkah.MainActivity}: java.lang.NullPointerException: Attempt to invoke virtual method 'void com.yk.danaberkah._sliders.SliderView.setDurationScroll(int)' on a null object reference
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2363)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2426)
at android.app.ActivityThread.access$800(ActivityThread.java:176)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1343)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:135)
at android.app.ActivityThread.main(ActivityThread.java:5417)
at java.lang.reflect.Method.invoke(Native Method)
at java.lang.reflect.Method.invoke(Method.java:372)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:902)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:697)
Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'void com.yk.danaberkah._sliders.SliderView.setDurationScroll(int)' on a null object reference
at com.yk.danaberkah.MainActivity.setupSlider(MainActivity.java:162)
at com.yk.danaberkah.MainActivity.onCreate(MainActivity.java:96)
at android.app.Activity.performCreate(Activity.java:5990)
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1108)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2316)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2426)
at android.app.ActivityThread.access$800(ActivityThread.java:176)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1343)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:135)
at android.app.ActivityThread.main(ActivityThread.java:5417)
at java.lang.reflect.Method.invoke(Native Method)
at java.lang.reflect.Method.invoke(Method.java:372)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:902)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:697)
Application terminated.This My MainActivity.java
Java:
public class MainActivity extends AppCompatActivity
implements NavigationView.OnNavigationItemSelectedListener {
private SliderPagerAdapter mAdapter;
private SliderIndicator mIndicator;
private String TAG = MainActivity.class.getSimpleName();
private SliderView sliderView;
private LinearLayout mLinearLayout;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
Toolbar toolbar = findViewById(R.id.toolbar);
setSupportActionBar(toolbar);
sliderView = (SliderView) findViewById(R.id.sliderView);
mLinearLayout = (LinearLayout) findViewById(R.id.pagesContainer);
setupSlider();
/*Slider Setup Example Use URLS*/
private void setupSlider() {
sliderView.setDurationScroll(800);
List<Fragment> fragments = new ArrayList<>();
fragments.add(FragmentSlider.newInstance("https://jssorcdn7.azureedge.net/demos/img/gallery/980x380/001.jpg"));
fragments.add(FragmentSlider.newInstance("https://www.dnvgl.co.uk/Images/ISO2015-revisions-1134x350_tcm12-13061.jpg"));
fragments.add(FragmentSlider.newInstance("https://www.dnvgl.co.uk/Images/ISO2015-revisions-1134x350_tcm12-13061.jpg"));
fragments.add(FragmentSlider.newInstance("https://jssorcdn7.azureedge.net/demos/img/gallery/980x380/001.jpg"));
Log.e(TAG, "Response from fragment: " + sliderView);
mAdapter = new SliderPagerAdapter(getSupportFragmentManager(), fragments);
sliderView.setAdapter(mAdapter);
mIndicator = new SliderIndicator(this, mLinearLayout, sliderView, R.drawable.indicator_circle);
mIndicator.setPageCount(fragments.size());
mIndicator.show();
}
}
}This FragmentSlider.java
Code:
public class FragmentSlider extends Fragment {
private static final String ARG_PARAM1 = "params";
private String imageUrls;
public FragmentSlider() {
}
public static FragmentSlider newInstance(String params) {
FragmentSlider fragment = new FragmentSlider();
Bundle args = new Bundle();
args.putString(ARG_PARAM1, params);
fragment.setArguments(args);
return fragment;
}
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
imageUrls = getArguments().getString(ARG_PARAM1);
View view = inflater.inflate(R.layout.fragment_slider, container, false);
ImageView img = (ImageView) view.findViewById(R.id.image_slider);
Glide.with(getActivity())
.load(imageUrls)
.placeholder(R.drawable.beras_murah)
.into(img);
return view;
}
}This SliderIndicator.java
Java:
public class SliderIndicator implements ViewPager.OnPageChangeListener {
private Context mContext;
private LinearLayout mContainer;
private int mDrawable;
private int mSpacing;
private int mSize;
private ViewPager mViewPager;
private int mPageCount;
private int mInitialPage = 0;
private int defaultSizeInDp = 12;
private int defaultSpacingInDp = 12;
public SliderIndicator(@NonNull Context context,
@NonNull LinearLayout containerView,
@NonNull ViewPager viewPager,
@DrawableRes int drawableRes) {
if (context == null) {
throw new IllegalArgumentException("context cannot be null");
} else if (containerView == null) {
throw new IllegalArgumentException("containerView cannot be null");
} else if (viewPager == null) {
throw new IllegalArgumentException("ViewPager cannot be null");
} else if (viewPager.getAdapter() == null) {
throw new IllegalArgumentException("ViewPager does not have an adapter set on it.");
}
mContext = context;
mContainer = containerView;
mDrawable = drawableRes;
mViewPager = viewPager;
}
public void setPageCount(int pageCount) {
mPageCount = pageCount;
}
public void setInitialPage(int page) {
mInitialPage = page;
}
public void setDrawable(@DrawableRes int drawable) {
mDrawable = drawable;
}
public void setSpacingRes(@DimenRes int spacingRes) {
mSpacing = spacingRes;
}
public void setSize(@DimenRes int dimenRes) {
mSize = dimenRes;
}
public void show() {
initIndicators();
setIndicatorAsSelected(mInitialPage);
new Handler().postDelayed(new Runnable() {
@Override
public void run() {
mViewPager.setCurrentItem(1);
}
}, 2500);
}
private void initIndicators() {
if (mContainer == null || mPageCount <= 0) {
return;
}
mViewPager.addOnPageChangeListener(this);
Resources res = mContext.getResources();
mContainer.removeAllViews();
for (int i = 0; i < mPageCount; i++) {
View view = new View(mContext);
int dimen = mSize != 0 ? res.getDimensionPixelSize(mSize) : ((int) res.getDisplayMetrics().density * defaultSizeInDp);
int margin = mSpacing != 0 ? res.getDimensionPixelSize(mSpacing) : ((int) res.getDisplayMetrics().density * defaultSpacingInDp);
LinearLayout.LayoutParams lp = new LinearLayout.LayoutParams(dimen, dimen);
lp.setMargins(i == 0 ? 0 : margin, 0, 0, 0);
view.setLayoutParams(lp);
view.setBackgroundResource(mDrawable);
view.setSelected(i == 0);
mContainer.addView(view);
}
}
private void setIndicatorAsSelected(int index) {
if (mContainer == null) {
return;
}
for (int i = 0; i < mContainer.getChildCount(); i++) {
View view = mContainer.getChildAt(i);
view.setSelected(i == index);
}
}
@Override
public void onPageScrolled(int position, float positionOffset, int positionOffsetPixels) {
}
@Override
public void onPageSelected(int position) {
int index = position % mPageCount;
setIndicatorAsSelected(index);
final int moveTo = position + 1;
try {
new Handler().postDelayed(new Runnable() {
@Override
public void run() {
mViewPager.setCurrentItem(moveTo);
}
}, 2500);
}catch (Exception e){
}
}
@Override
public void onPageScrollStateChanged(int state) {
}
public void cleanup() {
mViewPager.clearOnPageChangeListeners();
}
}SliderPagerAdapter.java
Java:
public class SliderPagerAdapter extends FragmentStatePagerAdapter {
private static final String TAG = "SliderPagerAdapter";
List<Fragment> mFrags = new ArrayList<>();
public SliderPagerAdapter(FragmentManager fm, List<Fragment> frags) {
super(fm);
mFrags = frags;
}
[USER=1021285]@override[/USER]
public Fragment getItem(int position) {
int index = position % mFrags.size();
return FragmentSlider.newInstance(mFrags.get(index).getArguments().getString("params"));
}
[USER=1021285]@override[/USER]
public int getCount() {
return Integer.MAX_VALUE;
}
}SliderView.java
Java:
public class SliderView extends ViewPager {
public static final int DEFAULT_SCROLL_DURATION = 250;
// public static final int SLIDE_MODE_SCROLL_DURATION = 1000;
public SliderView(Context context) {
super(context);
init();
}
public SliderView(Context context, AttributeSet attrs) {
super(context, attrs);
init();
}
private void init() {
setDurationScroll(DEFAULT_SCROLL_DURATION);
this.setOnTouchListener(new OnTouchListener() {
@Override
public boolean onTouch(View v, MotionEvent event) {
return true;
}
});
}
public void setDurationScroll(int millis) {
try {
Class<?> viewpager = ViewPager.class;
Field scroller = viewpager.getDeclaredField("mScroller");
scroller.setAccessible(true);
scroller.set(this, new OwnScroller(getContext(), millis));
} catch (Exception e) {
e.printStackTrace();
}
}
public class OwnScroller extends Scroller {
private int durationScrollMillis = 1;
public OwnScroller(Context context, int durationScroll) {
super(context, new DecelerateInterpolator());
this.durationScrollMillis = durationScroll;
}
@Override
public void startScroll(int startX, int startY, int dx, int dy, int duration) {
super.startScroll(startX, startY, dx, dy, durationScrollMillis);
}
}
}What icon is this
- By Eyrovia
- Ask a question
- 3 Replies
Im having problems trying to figure out what app has this notification icon. Thank you
