我试图通过膨胀gridview来在标签布局中创建一个gridview，然后膨胀gridview内容，但似乎无法正常工作，我无法找到解决方案，感谢任何想要帮助我的人。< / p>
所以这里是我的主要活动代码
此代码包含我的标签：
package id.WKKR.ktcafe;
import java.util.ArrayList;
import gridAdapter.CafeAdapter;
import tabs.SlidingTabLayout;
import android.content.Context;
import android.content.Intent;
import android.content.res.Resources;
import android.graphics.drawable.Drawable;
import android.os.Bundle;
import android.support.annotation.Nullable;
import android.support.v7.app.ActionBarActivity;
import android.support.v4.app.Fragment;
import android.support.v4.app.FragmentManager;
import android.support.v4.app.FragmentPagerAdapter;
import android.support.v4.view.ViewPager;
import android.support.v4.widget.DrawerLayout;
import android.view.LayoutInflater;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.view.ViewGroup;
import android.widget.BaseAdapter;
import android.widget.GridView;
import android.widget.ImageView;
import android.widget.TextView;
import android.widget.Toast;
import android.support.v7.widget.Toolbar;
import android.text.Spannable;
import android.text.SpannableString;
import android.text.style.ImageSpan;
@SuppressWarnings("deprecation")
public class MenuUtama extends ActionBarActivity{
Toolbar toolbar;
private ViewPager mPager;
private SlidingTabLayout mTabs;
private GridView makananGrid;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_menu_utama);
toolbar = (Toolbar) findViewById(R.id.app_bar);
setSupportActionBar(toolbar);
getSupportActionBar().setHomeButtonEnabled(true);
NavDrawerFragment drawerFragment = (NavDrawerFragment)getSupportFragmentManager().findFragmentById(R.id.fragment_navigation_drawer);
drawerFragment.setUp(R.id.fragment_navigation_drawer,(DrawerLayout)findViewById(R.id.drawer_layout),toolbar);
mPager = (ViewPager) findViewById(R.id.MyPager);
mPager.setAdapter(new MyPagerAdapter(getSupportFragmentManager()));
mTabs = (SlidingTabLayout) findViewById(R.id.MyTabs);
mTabs.setDistributeEvenly(true);
mTabs.setCustomTabView(R.layout.custom_tab_view, R.id.tabsText);
mTabs.setBackgroundColor(getResources().getColor(R.color.orange));
mTabs.setSelectedIndicatorColors(getResources().getColor(R.color.brown));
mTabs.setViewPager(mPager);
//the problem is here, i got null pointer exception error
makananGrid = (GridView) findViewById(R.id.gridView);
makananGrid.setAdapter(new MyCafe(this));
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
getMenuInflater().inflate(R.menu.menu_utama, menu);
return true;
}
@Override
public boolean onOptionsItemSelected(MenuItem item) {
int id = item.getItemId();
if (id == R.id.action_settings) {
Toast.makeText(this, "This Is " + item.getTitle() + " Button", Toast.LENGTH_SHORT).show();
return true;
}
if (id == R.id.bill) {
startActivity(new Intent(this, BillTagihanAnda.class));
}
if (id == R.id.pesanan) {
startActivity(new Intent(this, DaftarPesananAnda.class));
}
if (id == R.id.callwaiter){
startActivity(new Intent(this, PanggilPelayan.class));
finish();
}
return super.onOptionsItemSelected(item);
}
class MyPagerAdapter extends FragmentPagerAdapter{
int icon[] = {R.drawable.ic_food, R.drawable.ic_drink,R.drawable.ic_desserts};
String[] tabsText = getResources().getStringArray(R.array.tabs);
public MyPagerAdapter(FragmentManager fm) {
super(fm);
tabsText = getResources().getStringArray(R.array.tabs);
}
@Override
public Fragment getItem(int position) {
MyFragment myFragment = MyFragment.getInstance(position);
return myFragment;
}
@Override
public CharSequence getPageTitle(int position) {
Drawable drawable = getResources().getDrawable(icon[position]);
drawable.setBounds(0, 0, 40, 40);
ImageSpan imageSpan = new ImageSpan(drawable);
SpannableString spannableString = new SpannableString(" ");
spannableString.setSpan(imageSpan, 0, spannableString.length(), Spannable.SPAN_EXCLUSIVE_EXCLUSIVE);
return spannableString;
}
@Override
public int getCount() {
return 3;
}
}
public static class MyFragment extends Fragment {
private TextView textView;
private GridView myGridView;
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,
@Nullable Bundle savedInstanceState) {
View layout = inflater.inflate(R.layout.my_fragment, container, false);
textView = (TextView) layout.findViewById(R.id.position);
myGridView = (GridView) layout.findViewById(R.id.gridView);
Bundle bundle = getArguments();
if (bundle != null)
{
textView.setText("The Page Selected is "+bundle.getInt("position"));
//i was trying to set the adapter here but always got an error, and i don't know why.
myGridView.setAdapter(new MyCafe(this));
}
return layout;
}
}
这是我的适配器，它会使gridview内容膨胀：
class Menus {
int imageId = 0;
String menus = "";
String menusPrices = "";
Menus(int imageId, String menus, String menusPrices) {
this.imageId = imageId;
this.menus = menus;
this.menusPrices = menusPrices;
}
}
class MyCafe extends BaseAdapter {
ArrayList < Menus > list;
Context context;
MyCafe(Context context) {
this.context = context;
list = new ArrayList < Menus > ();
Resources res = context.getResources();
String[] tempMenusNames = res.getStringArray(R.array.food);
String[] tempMenusPrices = res.getStringArray(R.array.foodprices);
int[] menusImages = {
R.drawable.makanana, R.drawable.makananb,
R.drawable.makananc, R.drawable.makanand,
R.drawable.makanane, R.drawable.makananf
};
for (int i = 0; i < 6; i++) {
Menus tempMenus = new Menus(menusImages[i], tempMenusNames[i],
tempMenusPrices[i]);
list.add(tempMenus);
}
}
public int getCount() {
// TODO Auto-generated method stub
return list.size();
}
public Object getItem(int i) {
// TODO Auto-generated method stub
return list.get(i);
}
public long getItemId(int i) {
// TODO Auto-generated method stub
return i;
}
class ViewHolder {
ImageView myMenus;
TextView myMenusText;
TextView MyMenusPrice;
ViewHolder(View v) {
myMenus = (ImageView) v.findViewById(R.id.imageView1);
myMenusText = (TextView) v.findViewById(R.id.textView1);
MyMenusPrice = (TextView) v.findViewById(R.id.textView2);
}
}
public View getView(int i, View view, ViewGroup viewGroup) {
// TODO Auto-generated method stub
View row = view;
ViewHolder holder = null;
if (row == null) {
LayoutInflater inflater = (LayoutInflater) context.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
row = inflater.inflate(R.layout.single_item, viewGroup, false);
holder = new ViewHolder(row);
row.setTag(holder);
} else {
holder = (ViewHolder) row.getTag();
}
Menus temp = list.get(i);
holder.myMenus.setImageResource(temp.imageId);
holder.myMenusText.setText(temp.menus);
holder.MyMenusPrice.setText(temp.menusPrices);
return row;
}
}
}
这是我的activity_menu_utama.xml：
<android.support.v4.widget.DrawerLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
xmlns:yourapp="http://schemas.android.com/apk/res-auto"
android:id="@+id/drawer_layout"
android:layout_width="match_parent"
android:layout_height="match_parent" >
<LinearLayout
xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical"
tools:context="id.WKKR.ktcafe.MenuUtama" >
<include
android:id="@+id/app_bar"
layout="@layout/app_bar" />
<tabs.SlidingTabLayout
android:id="@+id/MyTabs"
android:layout_width="match_parent"
android:layout_height="wrap_content" />
<android.support.v4.view.ViewPager
android:id="@+id/MyPager"
android:layout_width="match_parent"
android:layout_height="0dp"
android:layout_weight="1" />
</LinearLayout>
<fragment
android:id="@+id/fragment_navigation_drawer"
android:name="id.WKKR.ktcafe.NavDrawerFragment"
android:layout_width="@dimen/navigation_drawer_width"
android:layout_height="match_parent"
android:layout_gravity="start"
tools:layout="@layout/activity_nav_drawer_fragment"
yourapp:layout="@layout/activity_nav_drawer_fragment" />
</android.support.v4.widget.DrawerLayout>
这是我的错误logcat：
05 - 05 14: 43: 40.576: E / AndroidRuntime(4347): FATAL EXCEPTION: main
05 - 05 14: 43: 40.576: E / AndroidRuntime(4347): Process: id.WKKR.ktcafe, PID: 4347
05 - 05 14: 43: 40.576: E / AndroidRuntime(4347): java.lang.RuntimeException: Unable to start activity ComponentInfo {
id.WKKR.ktcafe / id.WKKR.ktcafe.MenuUtama
}: java.lang.NullPointerException
05 - 05 14: 43: 40.576: E / AndroidRuntime(4347): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java: 2318)
05 - 05 14: 43: 40.576: E / AndroidRuntime(4347): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java: 2396)
05 - 05 14: 43: 40.576: E / AndroidRuntime(4347): at android.app.ActivityThread.access$800(ActivityThread.java: 139)
05 - 05 14: 43: 40.576: E / AndroidRuntime(4347): at android.app.ActivityThread$H.handleMessage(ActivityThread.java: 1293)
05 - 05 14: 43: 40.576: E / AndroidRuntime(4347): at android.os.Handler.dispatchMessage(Handler.java: 102)
05 - 05 14: 43: 40.576: E / AndroidRuntime(4347): at android.os.Looper.loop(Looper.java: 149)
05 - 05 14: 43: 40.576: E / AndroidRuntime(4347): at android.app.ActivityThread.main(ActivityThread.java: 5257)
05 - 05 14: 43: 40.576: E / AndroidRuntime(4347): at java.lang.reflect.Method.invokeNative(Native Method)
05 - 05 14: 43: 40.576: E / AndroidRuntime(4347): at java.lang.reflect.Method.invoke(Method.java: 515)
05 - 05 14: 43: 40.576: E / AndroidRuntime(4347): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java: 793)
05 - 05 14: 43: 40.576: E / AndroidRuntime(4347): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java: 609)
05 - 05 14: 43: 40.576: E / AndroidRuntime(4347): at dalvik.system.NativeStart.main(Native Method)
05 - 05 14: 43: 40.576: E / AndroidRuntime(4347): Caused by: java.lang.NullPointerException
05 - 05 14: 43: 40.576: E / AndroidRuntime(4347): at id.WKKR.ktcafe.MenuUtama.onCreate(MenuUtama.java: 66)
05 - 05 14: 43: 40.576: E / AndroidRuntime(4347): at android.app.Activity.performCreate(Activity.java: 5411)
05 - 05 14: 43: 40.576: E / AndroidRuntime(4347): at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java: 1087)
05 - 05 14: 43: 40.576: E / AndroidRuntime(4347): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java: 2270)
05 - 05 14: 43: 40.576: E / AndroidRuntime(4347): ...11 more
答案 0 :(得分：1)
xml中没有gridView id的视图，因此findViewById(R.id.gridView)返回null。将带有android:id="@+id/gridView"的GridView添加到您的xml中，或者不要尝试将其添加到您的代码中。