SQLiteの注意点

        showBtn.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                Cursor c = db.query("person_table", new String[]{"name, age"},
                        null, null, null, null, null);
                boolean mov = c.moveToFirst();
                while (mov){
                    tv.append(String.format("%s: %d才", c.getString(0), c.getInt(1)));
                    tv.append("\n");
                    mov = c.moveToNext();
                }
                c.close();
                db.close();
            }
        });

c.close();
db.close();

を入れないとエラーを吐くので注意