这是我的MainActivity Code.In这我们在setOnItemClickListener中得到错误作为空指针异常并且它停止了我的app.give我一些建议我错了。我正在尝试使用顶部的图像和旁边的标题来实现自定义网格。
public class MainActivity extends AppCompatActivity {
//RecyclerView recyclerView;
private static final String TAG = "MainActivity";
private final String android_version_names[] = {
"Donut",
"Eclair",
"Froyo",
"Gingerbread",
"Honeycomb",
"Ice Cream Sandwich",
"Jelly Bean",
"KitKat",
"Lollipop",
"Marshmallow"
};
private final String android_image_urls[] = {
"https://api.learn2crack.com/android/images/donut.png",
"https://api.learn2crack.com/android/images/eclair.png",
"https://api.learn2crack.com/android/images/froyo.png",
"https://api.learn2crack.com/android/images/ginger.png",
"https://api.learn2crack.com/android/images/honey.png",
"https://api.learn2crack.com/android/images/icecream.png",
"https://api.learn2crack.com/android/images/jellybean.png",
"https://api.learn2crack.com/android/images/kitkat.png",
"https://api.learn2crack.com/android/images/lollipop.png",
"https://api.learn2crack.com/android/images/marshmallow.png"
};
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
initViews();
}
private void initViews(){
RecyclerView recyclerView = (RecyclerView)findViewById(R.id.card_recycler_view);
recyclerView.setHasFixedSize(true);
RecyclerView.LayoutManager layoutManager = new GridLayoutManager(getApplicationContext(),2);
recyclerView.setLayoutManager(layoutManager);
ArrayList<AndroidVersion> androidVersions = prepareData();
DataAdapter adapter = new DataAdapter(getApplicationContext(),androidVersions);
recyclerView.setAdapter(adapter);
DataAdapter mAdapter = null ;
mAdapter.setOnItemClickListener(new DataAdapter.ClickListener() {
@Override
public void onItemClick(int position, View v) {
Log.d(TAG, "onItemClick position: " + position);
}
});
}
private ArrayList<AndroidVersion> prepareData(){
ArrayList<AndroidVersion> android_version = new ArrayList<>();
for(int i=0;i<android_version_names.length;i++){
AndroidVersion androidVersion = new AndroidVersion();
androidVersion.setAndroid_version_name(android_version_names[i]);
androidVersion.setAndroid_image_url(android_image_urls[i]);
android_version.add(androidVersion);
}
return android_version;
}
}
这是我的适配器代码。
public class DataAdapter extends RecyclerView.Adapter<DataAdapter.ViewHolder> {
private ArrayList<AndroidVersion> android;
private Context context;
private static ClickListener clickListener;
public DataAdapter(Context context,ArrayList<AndroidVersion> android) {
this.android = android;
this.context = context;
}
@Override
public DataAdapter.ViewHolder onCreateViewHolder(ViewGroup viewGroup, int i) {
View view = LayoutInflater.from(viewGroup.getContext()).inflate(R.layout.row_layout, viewGroup, false);
return new ViewHolder(view);
}
@Override
public void onBindViewHolder(DataAdapter.ViewHolder viewHolder, int i) {
viewHolder.tv_android.setText(android.get(i).getAndroid_version_name());
Picasso.with(context).load(android.get(i).getAndroid_image_url()).resize(240, 120).into(viewHolder.img_android);
}
@Override
public int getItemCount() {
return android.size();
}
public static class ViewHolder extends RecyclerView.ViewHolder implements View.OnClickListener{
private TextView tv_android;
private ImageView img_android;
public ViewHolder(View view) {
super(view);
view.setOnClickListener(this);
tv_android = (TextView)view.findViewById(R.id.tv_android);
img_android = (ImageView) view.findViewById(R.id.img_android);
}
@Override
public void onClick(View v) {
clickListener.onItemClick(getAdapterPosition(), v);
}
}
public void setOnItemClickListener(ClickListener clickListener) {
DataAdapter.clickListener = clickListener;
}
public interface ClickListener {
void onItemClick(int position, View v);
}
}
答案 0 :(得分:1)
您在设置mAdapter = null
之前设置setOnItemClickListener
,将其删除
DataAdapter mAdapter = null ; //remove this line
adapter.setOnItemClickListener(new DataAdapter.ClickListener() {
@Override
public void onItemClick(int position, View v) {
Log.d(TAG, "onItemClick position: " + position);
}
});
您正在调用错误的适配器,您的实际变量为adapter
,并且您使用mAdapter
调用它,并将其值设置为ull
答案 1 :(得分:0)
试试这个
DataAdapter adapter = new DataAdapter(getApplicationContext(),androidVersions);
recyclerView.setAdapter(adapter);
adapter.setOnItemClickListener(new DataAdapter.ClickListener() {
@Override
public void onItemClick(int position, View v) {
Log.d(TAG, "onItemClick position: " + position);
}
});