After being told to use a RecyclerView instead of a ListView, I have tried to implement it along with a SearchView. However, I get a strange error about an object being null:
java.lang.NullPointerException: Attempt to invoke virtual method 'void android.support.v7.widget.RecyclerView.setLayoutManager(android.support.v7.widget.RecyclerView$LayoutManager)' on a null object reference
I currently have the following code:
SearchActivity.java
package com.rickteuthof.strangejourneycompendium;
import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.support.v7.widget.LinearLayoutManager;
import android.support.v7.widget.RecyclerView;
import android.widget.SearchView;
import java.util.ArrayList;
public class SearchActivity extends AppCompatActivity implements SearchView.OnQueryTextListener {
public static ArrayList<String> demonNames;
private SearchAdapter adapter;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
RecyclerView r = findViewById(R.id.recyclerView);
demonNames = MainActivity.demonNames;
adapter = new SearchAdapter(this, demonNames);
r.setLayoutManager(new LinearLayoutManager(getApplicationContext(), LinearLayoutManager.VERTICAL, false));
r.setAdapter(adapter);
SearchView s = findViewById(R.id.searchBar);
s.setOnQueryTextListener(this);
}
@Override
public boolean onQueryTextSubmit(String query) {
return false;
}
@Override
public boolean onQueryTextChange(String newText) {
adapter.filter(newText);
return false;
}
}
SearchAdapter.java
package com.rickteuthof.strangejourneycompendium;
import android.content.Context;
import android.support.annotation.NonNull;
import android.support.v7.widget.RecyclerView;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.TextView;
import java.util.ArrayList;
import java.util.Locale;
public class SearchAdapter extends RecyclerView.Adapter<SearchAdapter.MyViewHolder> {
private LayoutInflater inflater;
private ArrayList<String> demonNames;
private ArrayList<String> results;
public SearchAdapter(Context ctx, ArrayList<String> demonNames){
inflater = LayoutInflater.from(ctx);
this.demonNames = demonNames;
this.results = new ArrayList<String>();
this.results.addAll(SearchActivity.demonNames);
}
@NonNull
@Override
public SearchAdapter.MyViewHolder onCreateViewHolder(@NonNull ViewGroup parent, int viewType) {
View view = inflater.inflate(R.layout.recycler_item, parent, false);
return new MyViewHolder(view);
}
@Override
public void onBindViewHolder(@NonNull SearchAdapter.MyViewHolder holder, int position) {
holder.time.setText(demonNames.get(position));
}
@Override
public int getItemCount() {
return demonNames.size();
}
class MyViewHolder extends RecyclerView.ViewHolder{
TextView time;
public MyViewHolder(View itemView) {
super(itemView);
time = itemView.findViewById(R.id.result);
}
}
// Filter Class
public void filter(String charText) {
charText = charText.toLowerCase(Locale.getDefault());
SearchActivity.demonNames.clear();
if (charText.length() == 0) {
SearchActivity.demonNames.addAll(results);
} else {
for (String wp : results) {
if (wp.toLowerCase(Locale.getDefault()).contains(charText)) {
SearchActivity.demonNames.add(wp);
}
}
}
notifyDataSetChanged();
}
}
My dataset is a String array named demonNames which I try to filter to get the correct results in the RecyclerView.
Here are my xml layouts:
activity_search.xml
<?xml version="1.0" encoding="utf-8"?>
<android.support.constraint.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context=".SearchActivity">
<SearchView
android:id="@+id/searchBar"
android:layout_width="0dp"
android:layout_height="wrap_content"
android:layout_marginBottom="8dp"
android:layout_marginEnd="8dp"
android:layout_marginStart="8dp"
android:layout_marginTop="8dp"
app:layout_constraintBottom_toTopOf="@+id/recyclerView"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintHorizontal_bias="0.0"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent"
app:layout_constraintVertical_bias="0.0" />
<android.support.v7.widget.RecyclerView
android:id="@+id/recyclerView"
android:layout_width="0dp"
android:layout_height="0dp"
android:layout_marginBottom="8dp"
android:layout_marginEnd="8dp"
android:layout_marginStart="8dp"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toBottomOf="@+id/searchBar" >
</android.support.v7.widget.RecyclerView>
</android.support.constraint.ConstraintLayout>
recycler_item.xml
<?xml version="1.0" encoding="utf-8"?>
<android.support.constraint.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent">
<TextView
android:id="@+id/result"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginStart="16dp"
android:layout_marginTop="16dp"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent" />
</android.support.constraint.ConstraintLayout>
