ContextCompat.getcolor（）去空對象引用

我收到錯誤，當我設置顏色SlidingTabLayout對象。這裏是我的mainActivity，首先我發現getResource.getColor已被棄用..所以我使用contextCompat.getColor ..但現在它的空值。ContextCompat.getcolor（）去空對象引用

public class MainActivity extends AppCompatActivity { 

    private Toolbar toolbar; 
    private ViewPager mPager; 
    private SlidingTabLayout mTabs; 
    private MyPagerAdapter adapter; 
    Context context; 

    @Override 
    protected void onCreate(Bundle savedInstanceState) { 
     super.onCreate(savedInstanceState); 
     setContentView(R.layout.activity_main); 

     toolbar = (Toolbar) findViewById(R.id.app_bar); 
     mPager = (ViewPager) findViewById(R.id.pager); 
     mTabs = (SlidingTabLayout) findViewById(R.id.tabs); 

     setSupportActionBar(toolbar); 
     assert getSupportActionBar() != null; 
     getSupportActionBar().setDisplayShowHomeEnabled(true); 

     NavigationDrawerFragment navigationDrawerFragment = (NavigationDrawerFragment) 
       getSupportFragmentManager().findFragmentById(R.id.fragment_nav_drawer); 
     navigationDrawerFragment.setUp(R.id.fragment_nav_drawer, (DrawerLayout) findViewById(R.id.drawer_layout), toolbar); 

     adapter = new MyPagerAdapter(getSupportFragmentManager(),MainActivity.this); 
     mPager.setAdapter(adapter); 
     mTabs.setViewPager(mPager); 
     mTabs.setDistributeEvenly(true); 

     int bgColor = ContextCompat.getColor(context,R.color.colorAccent); 
     mTabs.setBackgroundColor(bgColor); 
     mTabs.setSelectedIndicatorColors(ContextCompat.getColor(context, R.color.colorAccent)); 
     mTabs.invalidate(); 
     mTabs.setCustomTabView(R.layout.custom_tab_view,R.id.tabText); 
    } 


    @Deprecated 
    public boolean onCreateOptionsMenu(Menu menu) { 
     getMenuInflater().inflate(R.menu.menu_main, menu); 
     return true; 
    } 

    @Deprecated 
    public boolean onOptionsItemSelected(MenuItem item) { 
     int id = item.getItemId(); 
     if (id == R.id.action_settings) { 

      return true; 
     } 
     if (id == R.id.navigate) { 
      startActivity(new Intent(this, SubActivity.class)); 
     } 

     return super.onOptionsItemSelected(item); 
    } 

    public static class MyFragment extends Fragment { 
     private TextView textView; 

     public static MyFragment getInstance(int position) { 
      MyFragment myFragment = new MyFragment(); 
      Bundle args = new Bundle(); 
      args.putInt("position", position); 
      myFragment.setArguments(args); 
      return myFragment; 
     } 


     @Override 
     public View onCreateView(LayoutInflater inflater,@Nullable ViewGroup container, Bundle savedInstanceState) { 
      View layout = inflater.inflate(R.layout.fragment_my, container, false); 
      textView = (TextView) layout.findViewById(R.id.position); 
      Bundle bundle = getArguments(); 
      if (bundle != null) { 
       textView.setText(bundle.getInt("position")); 
      } 
      return layout; 
     } 
    } 

    class MyPagerAdapter extends FragmentStatePagerAdapter { 
     Context mContext; 
     int icons[] = {R.drawable.home,R.drawable.hot_article,R.drawable.dizzy_person}; 
     String[] tabText = getResources().getStringArray(R.array.tabs); 
     public MyPagerAdapter(FragmentManager fm,Context context) { 
      super(fm); 
      this.mContext = context; 

     } 

     @Override 
     public Fragment getItem(int position) { 
      MyFragment myFragment = MyFragment.getInstance(position); 
      return myFragment; 
     } 

     @Override 
     public CharSequence getPageTitle(int position) { 
      Drawable drawable = ResourcesCompat.getDrawable(getResources(),icons[position],null); 
      drawable.setBounds(0, 0, 36, 36); 
      ImageSpan imageSpan = new ImageSpan(drawable); 
      SpannableString spannableString = new SpannableString(" "); 
      spannableString.setSpan(imageSpan,0,spannableString.length(), Spanned.SPAN_EXCLUSIVE_EXCLUSIVE); 
      return spannableString; 
     } 

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

是在有任何棉花糖新的方法來解決這個概率...幫助我..

來源

2016-02-25 Sagar Chavada

這是因爲上下文尚未初始化。我建議你不要在那裏飛行引用Context。 Activity是Context的一個子類。您可以直接使用this或NameOfActivity.this來訪問上下文。

int bgColor = ContextCompat.getColor(context,R.color.colorAccent);

應該

int bgColor = ContextCompat.getColor(this ,R.color.colorAccent);

來源

2016-02-25 10:34:06 Blackbelt

感謝諮詢..從來沒有使用過飛參考， n .. –

不客氣 – Blackbelt

變化context到MainActivity.this

用這種方式

int bgColor = ContextCompat.getColor(MainActivity.this,R.color.colorAccent); 
mTabs.setBackgroundColor(bgColor); 
mTabs.setSelectedIndicatorColors(ContextCompat.getColor(MainActivity.this, R.color.colorAccent));

來源

2016-02-25 10:34:08

使用ContextCompat.getColor(context, R.color.color_name)並檢查上下文是否爲空或您COLOR_NAME值確實存在

來源

2016-02-25 10:34:30 Jas

其活動。所以我們可以使用，

int bgColor = ContextCompat.getColor(MainActivity.this,R.color.colorAccent);

在片段我們可以使用的情況下，

int bgColor = ContextCompat.getColor(this.getActivity(),R.color.colorAccent);

來源

2017-10-17 12:20:01

如果你想修改基於異步數據庫上查看呼叫你可能想通過上下文到執行數據庫調用的方法你甚至可以跟隨this

private void dbCall(Activity activity){ 

     // perform the database call 
     int bgColor = ContextCompat.getColor(activity,R.color.colorAccent); 

}

來源

2017-12-10 20:34:51

ContextCompat.getcolor（）去空對象引用

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