RecyclerView（transactions_list_view）オブジェクトの1つがactivity_main.xmlに含まれておらず、別のRecyclerView（groups_list_view）にネストされていると問題があると思います。どちらも下記に含まれています。RecyclerViewヌルポインタ例外。
エラー：
03-22 22:04:51.433 15921-15921/com.example.android.myapplication E/AndroidRuntime: FATAL EXCEPTION: main Process: com.example.android.myapplication, PID: 15921 java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.android.myapplication/com.example.android.myapplication.MainActivity}: 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 at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2442) at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2502) at android.app.ActivityThread.access$900(ActivityThread.java:167) at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1361) at android.os.Handler.dispatchMessage(Handler.java:102) at android.os.Looper.loop(Looper.java:148) at android.app.ActivityThread.main(ActivityThread.java:5469) at java.lang.reflect.Method.invoke(Native Method) at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:770) at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:660) Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'void android.support.v7.widget.RecyclerView.setLayoutManager(android.support.v7.widget.RecyclerView$LayoutManager)' on a null object reference at com.example.android.myapplication.MainActivity.onCreate(MainActivity.java:37) at android.app.Activity.performCreate(Activity.java:6553) at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1108) at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2395) at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2502) at android.app.ActivityThread.access$900(ActivityThread.java:167) at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1361) at android.os.Handler.dispatchMessage(Handler.java:102) at android.os.Looper.loop(Looper.java:148) at android.app.ActivityThread.main(ActivityThread.java:5469) at java.lang.reflect.Method.invoke(Native Method) at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:770) at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:660)
MainActivity.java
package com.example.android.myapplication;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.support.v7.widget.LinearLayoutManager;
import android.support.v7.widget.RecyclerView;
import com.example.android.myapplication.data.GroupsContract;
import com.example.android.myapplication.data.GroupsDbHelper;
import com.example.android.myapplication.data.TestUtilGroups;
import com.example.android.myapplication.data.TestUtilTransaction;
import com.example.android.myapplication.data.TransactionsContract;
import com.example.android.myapplication.data.TransactionsDbHelper;
public class MainActivity extends AppCompatActivity {
private GroupsListAdapter mGroupsAdapter;
private TransactionsListAdapter mTransactionsAdapter;
private SQLiteDatabase mGroupsDb;
private SQLiteDatabase mTransactionsDb;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
RecyclerView groupsRecyclerView;
RecyclerView transactionsRecyclerView;
groupsRecyclerView = (RecyclerView) this.findViewById(R.id.all_groups_list_view);
transactionsRecyclerView = (RecyclerView) this.findViewById(R.id.transactions_list_view);
groupsRecyclerView.setLayoutManager(new LinearLayoutManager(this));
transactionsRecyclerView.setLayoutManager(new LinearLayoutManager(this));
GroupsDbHelper groupsDbHelper = new GroupsDbHelper(this);
TransactionsDbHelper transactionsDbHelper = new TransactionsDbHelper(this);
mGroupsDb = groupsDbHelper.getWritableDatabase();
mTransactionsDb = transactionsDbHelper.getWritableDatabase();
TestUtilGroups.insertFakeData(mGroupsDb);
TestUtilTransaction.insertFakeData(mTransactionsDb);
Cursor cursorGroups = getAllGroups();
Cursor cursorTransactions = getAllTransactions();
mGroupsAdapter = new GroupsListAdapter(this, cursorGroups);
mTransactionsAdapter = new TransactionsListAdapter(transactionsRecyclerView.getContext(), cursorTransactions);
groupsRecyclerView.setAdapter(mGroupsAdapter);
transactionsRecyclerView.setAdapter(mTransactionsAdapter);
}
private Cursor getAllGroups() {
return mGroupsDb.query(
GroupsContract.GroupsEntry.TABLE_NAME,
null,
null,
null,
null,
null,
GroupsContract.GroupsEntry._ID
);
}
private Cursor getAllTransactions() {
return mTransactionsDb.query(
TransactionsContract.TransactionsEntry.TABLE_NAME,
null,
null,
null,
null,
null,
TransactionsContract.TransactionsEntry._ID
);
}
}
activity_main.xml
<?xml version="1.0" encoding="utf-8"?>
<FrameLayout 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="com.example.android.myapplication.MainActivity">
<android.support.v7.widget.RecyclerView
android:id="@+id/all_groups_list_view"
android:layout_width="match_parent"
android:layout_height="match_parent">
</android.support.v7.widget.RecyclerView>
</FrameLayout>
TransactionsListAdapter.jav
package com.example.android.myapplication;
import android.content.Context;
import android.database.Cursor;
import android.support.v7.widget.RecyclerView;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.TextView;
import com.example.android.myapplication.data.GroupsContract;
import com.example.android.myapplication.data.TransactionsContract;
/**
* Created by max on 3/22/2017.
*/
public class TransactionsListAdapter extends RecyclerView.Adapter<TransactionsListAdapter.TransactionsViewHolder> {
private Context mContext;
private Cursor mCursor;
public TransactionsListAdapter(Context context, Cursor cursor) {
this.mContext = context;
this.mCursor = cursor;
}
@Override
public TransactionsListAdapter.TransactionsViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
LayoutInflater inflater = LayoutInflater.from(mContext);
View view = inflater.inflate(R.layout.transactions_list_item, parent, false);
return new TransactionsViewHolder(view);
}
@Override
public void onBindViewHolder(TransactionsListAdapter.TransactionsViewHolder holder, int position) {
if(!mCursor.moveToPosition(position))
return;
String transactionName = mCursor.getString(mCursor.getColumnIndex(TransactionsContract.TransactionsEntry.COLUMN_NAME));
String transactionAmount = mCursor.getString(mCursor.getColumnIndex(TransactionsContract.TransactionsEntry.COLUMN_AMOUNT));
String transactiongivenortaken = mCursor.getString(mCursor.getColumnIndex(TransactionsContract.TransactionsEntry.COLUMN_GIVEN_TAKEN));
holder.transactionNameTextView.setText(transactionName);
holder.transactionAmountTextView.setText(transactionAmount);
holder.transactionGivenortakenTextView.setText(transactiongivenortaken);
}
@Override
public int getItemCount() {
return mCursor.getCount();
}
class TransactionsViewHolder extends RecyclerView.ViewHolder{
TextView transactionNameTextView;
TextView transactionAmountTextView;
TextView transactionGivenortakenTextView;
public TransactionsViewHolder(View itemView){
super(itemView);
transactionNameTextView = (TextView) itemView.findViewById(R.id.transactions_list_name);
transactionAmountTextView = (TextView) itemView.findViewById(R.id.transactions_list_amount);
transactionGivenortakenTextView = (TextView) itemView.findViewById(R.id.transactions_list_givenortaken);
}
}
}
groups_list_item.xml
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:orientation="vertical"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:gravity="center_vertical"
android:layout_margin="16dp"
android:background="#fff"
android:elevation="4dp">
<TextView
android:id="@+id/group_name_text_view"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_margin="3sp"
android:text="Group_Name"
android:textSize="20sp" />
<TextView
android:id="@+id/group_type_text_view"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Group_Type"
android:textSize="20sp"
android:layout_margin="3sp"
android:layout_alignBaseline="@id/group_name_text_view"
android:layout_alignBottom="@+id/view"
android:layout_alignParentEnd="true"
android:textColor="@color/secondary_text"/>
<View
android:id="@+id/view"
android:layout_width="match_parent"
android:layout_height="1dp"
android:layout_marginLeft="2sp"
android:layout_marginRight="2sp"
android:background="@color/divider"
android:layout_alignBottom="@+id/group_name_text_view"/>
<android.support.v7.widget.RecyclerView
android:id="@+id/transactions_list_view"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:layout_alignTop="@+id/view">
</android.support.v7.widget.RecyclerView>
</RelativeLayout>
transactions_list_item.xml
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="horizontal"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:layout_margin="3sp">
<TextView
android:id="@+id/transactions_list_name"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:textSize="10sp"/>
<TextView
android:id="@+id/transactions_list_amount"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:textSize="10sp"/>
<TextView
android:id="@+id/transactions_list_givenortaken"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:textSize="10sp"/>
</LinearLayout>
below-としてはい、私はこれがうまくいくことを知っているけど、それは私がそれを表示する方法はありません。別のレイアウトファイルにRecyclerViewが必要です。 –