私は今、メモ帳アプリの基礎部分を作っていて、保存したメモの一覧を作ろうとしていますしかし、
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103-12 16:11:42.110 3665-3665/? E/AndroidRuntime: FATAL EXCEPTION: main 2 Process: com.lifeistech.android.techmemotyou, PID: 3665 3 java.lang.RuntimeException: Unable to start activity ComponentInfo{com.lifeistech.android.techmemotyou/com.lifeistech.android.techmemotyou.MainActivity}: java.lang.NullPointerException: Attempt to invoke virtual method 'java.lang.String com.activeandroid.TableInfo.getTableName()' on a null object reference 4 at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2416) 5 at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2476) 6 at android.app.ActivityThread.-wrap11(ActivityThread.java) 7 at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1344) 8 at android.os.Handler.dispatchMessage(Handler.java:102) 9 at android.os.Looper.loop(Looper.java:148) 10 at android.app.ActivityThread.main(ActivityThread.java:5417) 11 at java.lang.reflect.Method.invoke(Native Method) 12 at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:726) 13 at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:616) 14 Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'java.lang.String com.activeandroid.TableInfo.getTableName()' on a null object reference 15 at com.activeandroid.Cache.getTableName(Cache.java:156) 16 at com.activeandroid.query.From.addFrom(From.java:169) 17 at com.activeandroid.query.From.toSql(From.java:250) 18 at com.activeandroid.query.From.execute(From.java:298) 19 at com.lifeistech.android.techmemotyou.MainActivity.setMemoList(MainActivity.java:52) 20 at com.lifeistech.android.techmemotyou.MainActivity.onCreate(MainActivity.java:23) 21 at android.app.Activity.performCreate(Activity.java:6237) 22 at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1107) 23 at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2369) 24 at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2476) 25 at android.app.ActivityThread.-wrap11(ActivityThread.java) 26 at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1344) 27 at android.os.Handler.dispatchMessage(Handler.java:102) 28 at android.os.Looper.loop(Looper.java:148) 29 at android.app.ActivityThread.main(ActivityThread.java:5417) 30 at java.lang.reflect.Method.invoke(Native Method) 31 at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:726) 32 at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:616) 33
というエラーが出ます。どこがおかしいのでしょうか。
MainActivityは
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1package com.lifeistech.android.techmemotyou; 2 3import android.content.Intent; 4import android.support.v7.app.AppCompatActivity; 5import android.os.Bundle; 6import android.view.Menu; 7import android.view.MenuItem; 8import android.widget.ArrayAdapter; 9import android.widget.ListView; 10 11import com.activeandroid.query.Select; 12 13import java.util.List; 14 15public class MainActivity extends AppCompatActivity { 16 17 ListView listview; 18 @Override 19 protected void onCreate(Bundle savedInstanceState) { 20 super.onCreate(savedInstanceState); 21 setContentView(R.layout.activity_main); 22 listview = (ListView)findViewById(R.id.memo_list); 23 } 24 void setMemoList(){ 25 List<MemoDB> memoList = new Select().from(MemoDB.class).execute(); 26 ArrayAdapter<MemoDB> adapter = new ArrayAdapter<>(getApplicationContext(), R.layout.memo_row, memoList); 27 listview.setAdapter(adapter); 28 } 29 30 @Override 31 public void onResume(){ 32 super.onResume(); 33 setMemoList(); 34 } 35 36 @Override 37 public boolean onCreateOptionsMenu(Menu menu) { 38 getMenuInflater().inflate(R.menu.mamu_main, menu); 39 return true; 40 } 41 @Override 42 public boolean onOptionsItemSelected(MenuItem item) { 43 44 int id = item.getItemId(); 45 46 if (id == R.id.main_create) { 47 48 Intent intent = new Intent(MainActivity.this, MemoCreateActivity.class); 49 startActivity(intent); 50 51 return true; 52 } 53 return super.onOptionsItemSelected(item); 54 } 55}
です。onCreate以外のところでgetApplicationContext()を呼び出すとエラーになるらしいので、onCreateに移しても見たのですが、同じエラーになります。
ActiveAndroidを設定しているクラスはこんな感じです。
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1 2 3import com.activeandroid.Model; 4import com.activeandroid.annotation.Column; 5import com.activeandroid.annotation.Table; 6 7@Table(name = "memo_table") 8public class MemoDB extends Model{ 9 @Column (name = "title") 10 public String title; 11 12 @Column (name = "memo") 13 public String memo; 14 15 @Column (name = "date") 16 public String date; 17 18 @Override 19 public String toString(){ 20 return title; 21 } 22} 23```です。どこがおかしいのでしょうか。
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2016/03/12 10:18
2016/03/12 10:27