編集履歴

質問編集履歴

タイトルを直しました

2019/04/03 06:57

投稿

スコア15

test CHANGED Viewed

	@@ -1 +1 @@
1	- RecyclerViewのみを使ったリスト
1	+ RecyclerViewを使ったリストのレイアウトについて

test CHANGED Viewed

File without changes

使用したコードとエラーを追記しました。

2019/04/03 06:57

投稿

oimo_kenpi

スコア15

test CHANGED Viewed

File without changes

test CHANGED Viewed

@@ -12,12 +12,504 @@
 ### 該当のソースコード
-[RecycleViewの基本 - Qiita](https://qiita.com/naoi/items/f8a19d6278147e98bbc2)
-上などのRecyclerViewのサンプルコードに手を加える形でやっていますが、どう付け加えていけばよいのかわかりません。レイアウトの切り替えをinflateでやるということはわかっているのですが…。
-xmlやActivityの詳細なヒントを頂きたいです。お願いします。
+レイアウト
+```
+<?xml version="1.0" encoding="utf-8"?>
+<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
+    android:layout_width="match_parent"
+    android:layout_height="match_parent">
+    <TextView
+        android:layout_width="match_parent"
+        android:layout_height="wrap_content"
+        android:padding="3dp"
+        android:background="#FF0000"
+        android:text="New Text"
+        android:id="@+id/textView1" /> <!-- textViewn -->
+</LinearLayout>
+```
+```MyAdapter
+package com.example.myapplication;
+import android.content.Context;
+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.List;
+public class MyAdapter extends RecyclerView.Adapter<MyAdapter.ViewHolder>{
+    private final LayoutInflater inflater;
+    private final List<SampleItem> data;
+    public MyAdapter(Context context, List<SampleItem> data){
+        this.inflater = LayoutInflater.from(context);
+        this.data = data;
+    }
+    @Override
+    public ViewHolder onCreateViewHolder(ViewGroup parent, int viewType){
+        switch(viewType){
+            case 1:
+                return new Sample1ItemViewHolder(inflater.inflate(Sample1ItemViewHolder.LAYOUT_ID, parent, false));
+            case 2:
+                return new Sample2ItemViewHolder(inflater.inflate(Sample2ItemViewHolder.LAYOUT_ID, parent, false));
+            case 3:
+                return new Sample3ItemViewHolder(inflater.inflate(Sample3ItemViewHolder.LAYOUT_ID, parent, false));
+        }
+        return null;
+    }
+    @Override
+    public void onBindViewHolder(ViewHolder holder, int position){
+        switch(getItemViewType(position)){
+            case 1:
+                ((Sample1ItemViewHolder)holder).onBindItemViewHolder(data.get(position));
+                break;
+            case 2:
+                ((Sample2ItemViewHolder)holder).onBindItemViewHolder(data.get(position));
+                break;
+            case 3:
+                ((Sample3ItemViewHolder)holder).onBindItemViewHolder(data.get(position));
+                break;
+        }
+    }
+    public int getItemViewType(int position){
+        return data.get(position).getCategory();
+    }
+    @Override
+    public int getItemCount(){
+        return data.size();
+    }
+    public class ViewHolder extends RecyclerView.ViewHolder{
+        public ViewHolder(View itemView){
+            super(itemView);
+        }
+    }
+    public class Sample1ItemViewHolder extends ViewHolder{
+        public static final int LAYOUT_ID = R.layout.sample_1_item_view;
+        public final  TextView textView;
+        public  Sample1ItemViewHolder(View itemView){
+            super(itemView);
+            textView = itemView.findViewById(R.id.textView1);
+        }
+        public void onBindItemViewHolder(SampleItem data){
+            this.textView.setText(data.getText());
+        }
+    }
+    public class Sample2ItemViewHolder extends ViewHolder{
+        public static final int LAYOUT_ID = R.layout.sample_2_item_view;
+        public final  TextView textView;
+        public  Sample2ItemViewHolder(View itemView){
+            super(itemView);
+            textView = itemView.findViewById(R.id.textView2);
+        }
+        public void onBindItemViewHolder(SampleItem data){
+            this.textView.setText(data.getText());
+        }
+    }
+    public class Sample3ItemViewHolder extends ViewHolder{
+        public static final int LAYOUT_ID = R.layout.sample_3_item_view;
+        public final  TextView textView;
+        public  Sample3ItemViewHolder(View itemView){
+            super(itemView);
+            textView = itemView.findViewById(R.id.textView3);
+        }
+        public void onBindItemViewHolder(SampleItem data){
+            this.textView.setText(data.getText());
+        }
+    }
+}
+```
+```SampleItem
+package com.example.myapplication;
+public class SampleItem {
+    private String text;
+    private int category;
+    public SampleItem(int category, String text){
+        this.category = category;
+        this.text = text;
+    }
+    public String getText(){
+        return this.text;
+    }
+    public int getCategory(){
+        return this.category;
+    }
+}
+```
+```MainActivity
+package com.example.myapplication;
+import android.support.v7.app.AppCompatActivity;
+import android.support.v7.widget.LinearLayoutManager;
+import android.support.v7.widget.RecyclerView;
+import android.os.Bundle;
+import java.util.ArrayList;
+import java.util.List;
+public class MainActivity extends AppCompatActivity {
+    @Override
+    protected void onCreate(Bundle savedInstanceState) {
+        super.onCreate(savedInstanceState);
+        RecyclerView recyclerView = findViewById(R.id.recycler_view);
+        recyclerView.setHasFixedSize(true);
+        LinearLayoutManager layoutManager = new LinearLayoutManager(this);
+        recyclerView.setLayoutManager(layoutManager);
+        List<SampleItem> data = new ArrayList<>();
+        SampleItem item = null;
+        for (int i = 0; i < 30; i++){
+            switch(i % 10) {
+                case 0:
+                    item = new SampleItem(1, "Data" + i);
+                    break;
+                case 1:
+                    item = new SampleItem(1, "Data" + i);
+                    break;
+                case 2:
+                    item = new SampleItem(2, "Data" + i);
+                    break;
+                case 3:
+                    item = new SampleItem(3, "Data" + i);
+                    break;
+                case 4:
+                    item = new SampleItem(2, "Data" + i);
+                    break;
+                case 5:
+                    item = new SampleItem(1, "Data" + i);
+                    break;
+                case 6:
+                    item = new SampleItem(2, "Data" + i);
+                    break;
+                case 7:
+                    item = new SampleItem(2, "Data" + i);
+                    break;
+                case 8:
+                    item = new SampleItem(3, "Data" + i);
+                    break;
+                case 9:
+                    item = new SampleItem(1, "Data" + i);
+                    break;
+            }
+            data.add(item);
+        }
+        recyclerView.setAdapter(new MyAdapter(this, data));
+    }
+}
+```
+[RecycleViewで行ごとに表示を切り替える](https://woshidan.hatenablog.com/entry/2015/11/02/083000)
+上のよさげなコードを試してみたのですが、アプリが停止します。
+Logcatのエラー
+> E/AndroidRuntime: FATAL EXCEPTION: main
+    Process: com.example.myapplication, PID: 12165
+    java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.myapplication/com.example.myapplication.MainActivity}: java.lang.NullPointerException: Attempt to invoke virtual method 'void android.support.v7.widget.RecyclerView.setHasFixedSize(boolean)' on a null object reference
+        at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2665)
+        at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2726)
+        at android.app.ActivityThread.-wrap12(ActivityThread.java)
+        at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1477)
+        at android.os.Handler.dispatchMessage(Handler.java:102)
+        at android.os.Looper.loop(Looper.java:154)
+        at android.app.ActivityThread.main(ActivityThread.java:6119)
+        at java.lang.reflect.Method.invoke(Native Method)
+        at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:886)
+        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:776)
+     Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'void android.support.v7.widget.RecyclerView.setHasFixedSize(boolean)' on a null object reference
+        at com.example.myapplication.MainActivity.onCreate(MainActivity.java:19)
+        at android.app.Activity.performCreate(Activity.java:6679)
+        at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1118)
+        at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2618)
+        at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2726)
+        at android.app.ActivityThread.-wrap12(ActivityThread.java)
+        at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1477)
+        at android.os.Handler.dispatchMessage(Handler.java:102)
+        at android.os.Looper.loop(Looper.java:154)
+        at android.app.ActivityThread.main(ActivityThread.java:6119)
+        at java.lang.reflect.Method.invoke(Native Method)
+        at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:886)
+        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:776)
+お願いします。