构建 Android 启动器

Question

我正在构建一个 Android 启动器，但在尝试将已安装的应用程序添加到 GridView 时不断崩溃。

我正在尝试在网格视图中添加已安装应用程序的网格。

我的gridview代码是

 private void loadGridView() {
    grid = (GridView) getActivity().findViewById(R.id.content);

    ArrayAdapter<AppDetail> adapter = new ArrayAdapter<AppDetail>(getActivity(), android.R.layout.simple_list_item_1, apps) {
      @Override
        public View getView(int position, View convertView, ViewGroup parent) {
          if (convertView == null) {
              convertView = getActivity().getLayoutInflater().inflate(R.layout.drawer_item, null);
          }

          ImageView appIcon = (ImageView) convertView.findViewById(R.id.icon_image);
          appIcon.setImageDrawable(apps.get(position).icon);

          TextView appLabel = (TextView) convertView.findViewById(R.id.icon_text);
          appLabel.setText(apps.get(position).label);

          return convertView;
      }
    };

    grid.setAdapter(adapter);
}

谢谢

编辑 1 - 这是我的崩溃日志

Process: com.jenovaprojects.ubuntutouchlauncher, PID: 19156

Theme: themes:{}

java.lang.NullPointerException: Attempt to invoke virtual method 'void 
android.widget.GridView.setAdapter(android.widget.ListAdapter)' on a 
null object reference

at 

com.jenovaprojects.ubuntutouchlauncher.homescreenfragments
.AppsScope.load
GridView(AppsScope.java:156)

at 
com.jenovaprojects.ubuntutouchlauncher.homescreenfragments
.AppsScope.onCr
eateView(AppsScope.java:109)

at 
android.support.v4.app.Fragment.performCreateView(Fragment.java:2192)

at 
android.support.v4.app.FragmentManagerImpl.moveToState
(FragmentManager.ja
va:1299)

at 
android.support.v4.app.FragmentManagerImpl.
moveFragmentToExpectedState(Fr
agmentManager.java:1528)

at 
android.support.v4.app.FragmentManagerImpl.
moveToState(FragmentManager.ja
va:1595)

 at 
 android.support.v4.app.BackStackRecord.executeOps
 (BackStackRecord.java:75
 8)

at 
android.support.v4.app.FragmentManagerImpl.executeOps
(FragmentManager.jav
a:2363)

at 
android.support.v4.app.FragmentManagerImpl.executeOpsTogether
(FragmentMan
ager.java:2149)

at 
android.support.v4.app.FragmentManagerImpl.optimizeAndExecuteOps
(Fragment
Manager.java:2103)

at 
android.support.v4.app.FragmentManagerImpl.execSingleAction
(FragmentManag
er.java:1984)

在 android.support.v4.app.BackStackRecord.commitNowAllowingStateLoss （BackSta ckRecord.java:626)

at 
android.support.v4.app.FragmentPagerAdapter.finishUpdate
(FragmentPagerAda
pter.java:143)

at android.support.v4.view.ViewPager.populate(ViewPager.java:1268)

at android.support.v4.view.ViewPager.populate(ViewPager.java:1116)

at android.support.v4.view.ViewPager.onMeasure(ViewPager.java:1642)

at android.view.View.measure(View.java:18799)

at 
android.support.constraint.ConstraintLayout.internalMeasureChildren
(Const
raintLayout.java:934)

at 
android.support.constraint.ConstraintLayout.onMeasure
(ConstraintLayout.ja
va:973)

at android.view.View.measure(View.java:18799)

at android.view.ViewGroup.measureChildWithMargins
(ViewGroup.java:5951)

at 
android.support.design.widget.CoordinatorLayout.
onMeasureChild(Coordinato
rLayout.java:714)

at 
android.support.design.widget.HeaderScrollingViewBehavior.
onMeasureChild(
HeaderScrollingViewBehavior.java:90)

at 
android.support.design.widget.
AppBarLayout$ScrollingViewBehavior.onMeasur
 eChild(AppBarLayout.java:1391)

at 
android.support.design.widget.CoordinatorLayout.
onMeasure(CoordinatorLayo
ut.java:784)

at android.view.View.measure(View.java:18799)

at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5951)

at android.widget.FrameLayout.onMeasure(FrameLayout.java:194)

at 
android.support.v7.widget.ContentFrameLayout.onMeasure
(ContentFrameLayout
.java:139)

at android.view.View.measure(View.java:18799)

at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5951)

at 
android.widget.LinearLayout.measureChildBeforeLayout
(LinearLayout.java:14
58)

at android.widget.LinearLayout.measureVertical(LinearLayout.java:746)

at android.widget.LinearLayout.onMeasure(LinearLayout.java:629)

at android.view.View.measure(View.java:18799)

at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5951)

at android.widget.FrameLayout.onMeasure(FrameLayout.java:194)

at android.view.View.measure(View.java:18799)

at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5951)

at 
android.widget.LinearLayout.measureChildBeforeLayout
(LinearLayout.java:14
58)

at android.widget.LinearLayout.measureVertical(LinearLayout.java:746)

at android.widget.LinearLayout.onMeasure(LinearLayout.java:629)

at android.view.View.measure(View.java:18799)

at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5951)

at android.widget.FrameLayout.onMeasure(FrameLayout.java:194)

at 
com.android.internal.policy.PhoneWindow$DecorView.onMeasure
(PhoneWindow.j
ava:2899)

at android.view.View.measure(View.java:18799)

at android.view.ViewRootImpl.performMeasure(ViewRootImpl.java:2108)

at android.view.ViewRootImpl.measureHierarchy(ViewRootImpl.java:1224)

at android.view.ViewRootImpl.performTraversals(ViewRootImpl.ja

Answer 1

问题是 (GridView) getActivity().findViewById(R.id.content) 返回 null。这会导致崩溃：

grid.setAdapter(adapter); 

要解决检查你的网格的 id 是什么，然后这样写：

grid = (GridView) getActivity().findViewById(R.id.your_grid_view);