java - ListView 选中的复选框

Question

我正在创建一个用于交流学习的 Android 应用程序

我做了一个word的List，里面包含了一个CheckBoxes和TextView，TextView是用来显示这个word的，CheckBox的作用是判断我选中了ListView中的哪个item。

我使用“提交”按钮将单词的 ID 存储在 SQLite 中。当我关闭并再次打开 Activity 时，我想看到选中的复选框，但此代码仅保存到我的数据库中，但在我再次打开 Activity 时不显示所选项目

这是 Activity

public class PerkembanganLevel1 extends AppCompatActivity{

    private ContentDao contentDao;
    private ChildDao childDao;
    private Child anakYangDipilih;

    public Global global;

    private AssessmentDao assessmentDao;
    private Assessment assessment;

    String idYangSudahBisa;

    PerkembanganAdapter perkembanganAdapter = null;

    ContentHistory contentHistory;


    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_perkembangan_level1);

        contentDao = new ContentDao(this);
        contentDao.open();

        childDao = new ChildDao(this);
        childDao.open();

        anakYangDipilih = ((Global) getApplicationContext()).getChild();

        idYangSudahBisa = anakYangDipilih.getLevel1();

        ArrayList<ContentHistory> listKataLevel1 = (ArrayList<ContentHistory>) contentDao.getAllWordByLevel(1);

        perkembanganAdapter = new PerkembanganAdapter(this, R.layout.list_perkembangan, listKataLevel1);

        ListView level1 =  findViewById(R.id.LVPlv1);
        level1.setAdapter(perkembanganAdapter);
        Log.i("listKataLevel1 ", String.valueOf(listKataLevel1));
        level1.setOnItemClickListener(new AdapterView.OnItemClickListener() {
            @Override
            public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
                contentHistory = (ContentHistory) parent.getItemAtPosition(position);

            }
        });
        findViewById(R.id.BtnPLv1Submit).setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                idYangSudahBisa = perkembanganAdapter.idYangSudahBisa();

                anakYangDipilih.getId();
                anakYangDipilih.setLevel1(idYangSudahBisa);
                anakYangDipilih.setCreatedBy(((Global) getApplicationContext()).getTherapist().getId());
                anakYangDipilih.setUpdatedBy(((Global) getApplicationContext()).getTherapist().getId());
                anakYangDipilih.setCreatedDate(new Date());
                anakYangDipilih.setUpdatedDate(new Date());
                anakYangDipilih = childDao.saveChild(anakYangDipilih);

                Toast.makeText(PerkembanganLevel1.this, "Perkembangan Anak pada level 1 Berhasil Diperbarui", Toast.LENGTH_SHORT).show();
            }
        });


    }

}

这是适配器

public class PerkembanganAdapter extends ArrayAdapter<ContentHistory> {


    String idYangSudahBisa;

    private ChildDao childDao;
    private Child anakYangDipilih;

    public ArrayList<ContentHistory> contentHistories;

    public PerkembanganAdapter(Context context, int id, ArrayList<ContentHistory> contentHistories){
        super(context, id, contentHistories);
        this.contentHistories = new ArrayList<>();
        this.contentHistories.addAll(contentHistories);



        childDao = new ChildDao(getContext());
        childDao.open();

        anakYangDipilih = ((Global) context.getApplicationContext()).getChild();
        this.idYangSudahBisa = anakYangDipilih.getLevel1();

    }

    private class ViewHolder{
        TextView title;
        CheckBox checkBoxes;
    }

    @NonNull
    @Override
    public View getView(int position, @Nullable View convertView, @NonNull ViewGroup parent) {

        ViewHolder viewHolder = null;
        if (convertView == null){
            LayoutInflater layoutInflater = (LayoutInflater) parent.getContext().getSystemService(Context.LAYOUT_INFLATER_SERVICE);
            convertView = layoutInflater.inflate(R.layout.list_perkembangan, null);

            viewHolder = new ViewHolder();
            viewHolder.title = convertView.findViewById(R.id.TVListPerkembangan);
            viewHolder.checkBoxes = convertView.findViewById(R.id.CBListPerkembangan);

            convertView.setTag(viewHolder);

            viewHolder.checkBoxes.setOnClickListener(new View.OnClickListener() {
                @Override
                public void onClick(View v) {
                    CheckBox checkBox = (CheckBox) v;
                    ContentHistory contentHistory = (ContentHistory) checkBox.getTag();
                    contentHistory.setSelected(checkBox.isChecked());
                    if (checkBox.isChecked()){
                        idYangSudahBisa = idYangSudahBisa + ","+contentHistory.getId();
                        //Toast.makeText(getContext(), ""+idYangSudahBisa,Toast.LENGTH_SHORT).show();
                    } else {
                        idYangSudahBisa = idYangSudahBisa.replace(","+contentHistory.getId(), "");
                        //Toast.makeText(getContext(), ""+idYangSudahBisa,Toast.LENGTH_SHORT).show();
                    }

                }
            });



        } else {
            viewHolder = (ViewHolder) convertView.getTag();
        }


        ContentHistory contentHistory = contentHistories.get(position);
        viewHolder.title.setText(contentHistory.getTitle());

        viewHolder.checkBoxes.setChecked(contentHistory.getSelected());
        viewHolder.checkBoxes.setTag(contentHistory);


        return convertView;

    }

    public String idYangSudahBisa(){

        return this.idYangSudahBisa;
    }

}
...

Answer 1

不需要提交按钮，因为您可以在单击复选框时实时更新(切换)数据库。

重要的方面是在 ContentDao 中添加一个方法，例如:-

public void toggleCheckedById(long id) {

    db.execSQL(
            "UPDATE " + TABLE_NAME +
                    " SET " + COLUMN_CHECKED + " = NOT  " + COLUMN_CHECKED +
                    " WHERE " + COLUMN_ID + "=?",
            new String[]{String.valueOf(id)}
    );
}

• 这等同于 UPDATE the_table SET the_check_column = NOT the_check_column WHERE the_id_column =?
  • 注意到了吗？使用传递给 execSQL 的第二个参数替换(绑定(bind))，在本例中，它是一个包含单个元素的字符串 []，该元素是要更改的行的 id。

这可以从 CheckBox 的 onClick 调用，传递从 View 标签中提取的 id。

考虑一下你的代码的这个简化版本:-

数据库助手(可能是您的 Global.java 类)DatabaseHelper.java :-

public class DatabaseHelper extends SQLiteOpenHelper {

    public static final String DBNAME = "perkembangan.db";
    public static final int DBVERSION = 1;

    private static DatabaseHelper sInstance;

    private DatabaseHelper(Context context) {
        super(context, DBNAME, null, DBVERSION);
    }

    public static synchronized DatabaseHelper getInstance(Context context) {
        if (sInstance == null) {
            sInstance = new DatabaseHelper(context);
        }
        return sInstance;
    }

    @Override
    public void onCreate(SQLiteDatabase db) {
        String createContentSQL = "CREATE TABLE IF NOT EXISTS " + ContentDao.TABLE_NAME +
        "(" +
                ContentDao.COLUMN_ID + " INTEGER PRIMARY KEY, " +
                ContentDao.COLUMN_NAME + " TEXT, " +
                ContentDao.COLUMN_CHECKED + " INTEGER DEFAULT 0" +
                ")";
        db.execSQL(createContentSQL);
        /* ADD SOME TESTING DATA WHEN THE DATABASE IS CREATED */
        ContentValues cv = new ContentValues();
        for (int i=0; i < 3; i++) {
            cv.clear();
            cv.put(ContentDao.COLUMN_NAME,"Name" + String.valueOf(i));
            db.insert(ContentDao.TABLE_NAME,null,cv);
        }
    }

    @Override
    public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {

    }

    public static String qualifyColumnName(String table, String column) {
        return table + "." + column;
    }
}

• 请注意，这会添加 3 行用于测试。
• 你可能不需要这个。

ContentDao.java(对其的解释):-

public class ContentDao {

    private static DatabaseHelper sInstance;
    private static SQLiteDatabase db;

    public static final String TABLE_NAME = "content";
    public static final String COLUMN_ID = BaseColumns._ID;
    public static final String QUALIFIEDCOLUMN_ID = DatabaseHelper.qualifyColumnName(TABLE_NAME,COLUMN_ID);
    public static final String COLUMN_NAME = "name";
    public static final String COLUMN_CHECKED = "checked";



    public ContentDao(Context context) {
        db =(sInstance = DatabaseHelper.getInstance(context)).getWritableDatabase();
    }

    public void toggleCheckedById(long id) {

        db.execSQL(
                "UPDATE " + TABLE_NAME +
                        " SET " + COLUMN_CHECKED + " = NOT  " + COLUMN_CHECKED +
                        " WHERE " + COLUMN_ID + "=?",
                new String[]{String.valueOf(id)}
        );
    }

    public SQLiteDatabase getDb() {
        return db;
    }

    public int updateCheckedById(ContentHistory ch) {
        ContentValues cv = new ContentValues();
        cv.put(COLUMN_CHECKED,ch.isChecked());
        return db.update(TABLE_NAME,cv,COLUMN_ID + "=?",new String[]{String.valueOf(ch.getId())});
    }

    public ArrayList<ContentHistory> getContentHistory() {
        ArrayList<ContentHistory> rv = new ArrayList<>();
        Cursor csr = db.query(TABLE_NAME,null,null,null,null,null,null);
        while (csr.moveToNext()) {
            rv.add(new ContentHistory(csr.getLong(csr.getColumnIndex(COLUMN_ID)),
                    csr.getString(csr.getColumnIndex(COLUMN_NAME)),
                    csr.getInt(csr.getColumnIndex(COLUMN_CHECKED))> 0)
            );
        }
        csr.close();
        return rv;
    }



    public class ContentHistory {
        private long id;
        private String name;
        private boolean checked;

        ContentHistory(long id, String name, boolean checked) {
            this.id = id;
            this.name = name;
            this.checked = checked;
        }

        public long getId() {
            return id;
        }

        public void setId(long id) {
            this.id = id;
        }

        public String getName() {
            return name;
        }

        public void setName(String name) {
            this.name = name;
        }

        public boolean isChecked() {
            return checked;
        }

        public void setChecked(boolean checked) {
            this.checked = checked;
        }
    }
}

• 注意为方便起见，包含了 ContentHistory 类
• 名称已被使用而不是标题(直到后来才意识到)
• 如前所述，重要的添加是 toggleCheckedById 方法。

PerkembanganAdapter.java

public class PerkembanganAdapter extends ArrayAdapter<ContentDao.ContentHistory> {

    ContentDao contentDao;


    public ArrayList<ContentDao.ContentHistory> contentHistories;

    public PerkembanganAdapter(Context context, int id, ArrayList<ContentDao.ContentHistory> contentHistories){
        super(context, id, contentHistories);
        contentDao = new ContentDao(context);
        this.contentHistories = new ArrayList<>();
        this.contentHistories.addAll(contentHistories);
        /*
        childDao = new ChildDao(getContext());
        childDao.open();

        anakYangDipilih = ((Global) context.getApplicationContext()).getChild();
        this.idYangSudahBisa = anakYangDipilih.getLevel1();

        */

    }

    private class ViewHolder{
        TextView title;
        CheckBox checkBoxes;
    }

    @Override
    public View getView(int position, View convertView, ViewGroup parent) {

        ViewHolder viewHolder;
        if (convertView == null){
            LayoutInflater layoutInflater = (LayoutInflater) parent.getContext().getSystemService(Context.LAYOUT_INFLATER_SERVICE);
            convertView = layoutInflater.inflate(R.layout.list_perkembangan, null);

            viewHolder = new ViewHolder();
            viewHolder.title = convertView.findViewById(R.id.TVListPerkembangan);
            viewHolder.checkBoxes = convertView.findViewById(R.id.CBListPerkembangan);

            convertView.setTag(viewHolder);

            viewHolder.checkBoxes.setOnClickListener(new View.OnClickListener() {
                @Override
                public void onClick(View v) {
                    CheckBox checkBox = (CheckBox) v;
                    ContentDao.ContentHistory contentHistory = (ContentDao.ContentHistory) checkBox.getTag();
                    contentHistory.setChecked(checkBox.isChecked());
                    contentDao.toggleCheckedById(contentHistory.getId()); //<<<<< will update (toggle) database in real time
                    /* NOT NEEDED
                    if (checkBox.isChecked()){
                        //idYangSudahBisa = idYangSudahBisa + ","+contentHistory.getId();
                        //Toast.makeText(v.getContext(), ""+idYangSudahBisa,Toast.LENGTH_SHORT).show();
                    } else {
                        //idYangSudahBisa = idYangSudahBisa.replace(","+contentHistory.getId(), "");
                        //Toast.makeText(getContext(), ""+idYangSudahBisa,Toast.LENGTH_SHORT).show();
                    }
                     */
                }
            });
        } else {
            viewHolder = (ViewHolder) convertView.getTag();
        }

        ContentDao.ContentHistory contentHistory = contentHistories.get(position);
        viewHolder.title.setText(contentHistory.getName());
        viewHolder.checkBoxes.setChecked(contentHistory.isChecked());
        viewHolder.checkBoxes.setTag(contentHistory);
        return convertView;
    }
}

• 请注意，大部分原始代码已被注释掉，只保留了演示所需的重要代码。
• 为方便起见，似乎是外语名称的名称也已被省略/更改。
• 显然，代码必须进行调整以适应。这是正在演示的技术。

PerkembanganLevel1.java Activity :-

public class PerkembanganLevel1 extends AppCompatActivity{

    private ContentDao contentDao;
    private ListView level1;
    private PerkembanganAdapter perkembanganAdapter;
    private ArrayList<ContentDao.ContentHistory> contentHistory;



    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_perkembangan_level1);
        level1 = this.findViewById(R.id.level1);

        contentDao = new ContentDao(this);
        manageListView();

        /*contentDao.open();

        childDao = new ChildDao(this);
        childDao.open();

        anakYangDipilih = ((Global) getApplicationContext()).getChild();

        idYangSudahBisa = anakYangDipilih.getLevel1();

         */

        /*
        ArrayList<ContentDao.ContentHistory> listKataLevel1 = (ArrayList<ContentDao.ContentHistory>) contentDao.getAllWordByLevel(1);

        perkembanganAdapter = new PerkembanganAdapter(this, R.layout.list_perkembangan, listKataLevel1);

        //ListView level1 =  findViewById(R.id.LVPlv1);
        level1.setAdapter(perkembanganAdapter);
        Log.i("listKataLevel1 ", String.valueOf(listKataLevel1));
        level1.setOnItemClickListener(new AdapterView.OnItemClickListener() {
            @Override
            public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
                contentHistory = (ContentDao.ContentHistory) parent.getItemAtPosition(position);

            }
        });
        findViewById(R.id.BtnPLv1Submit).setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                idYangSudahBisa = perkembanganAdapter.idYangSudahBisa();

                anakYangDipilih.getId();
                anakYangDipilih.setLevel1(idYangSudahBisa);
                anakYangDipilih.setCreatedBy(((Global) getApplicationContext()).getTherapist().getId());
                anakYangDipilih.setUpdatedBy(((Global) getApplicationContext()).getTherapist().getId());
                anakYangDipilih.setCreatedDate(new Date());
                anakYangDipilih.setUpdatedDate(new Date());
                anakYangDipilih = childDao.saveChild(anakYangDipilih);

                Toast.makeText(PerkembanganLevel1.this, "Perkembangan Anak pada level 1 Berhasil Diperbarui", Toast.LENGTH_SHORT).show();
            }
        });

         */

    }

    /* Will refresh the Listview when returning from an invoked activity just in case data has changed */
    @Override
    protected void onResume() {
        super.onResume();
        manageListView();
    }

    private void manageListView() {
        contentHistory = contentDao.getContentHistory();
        if (perkembanganAdapter == null) {
            perkembanganAdapter = new PerkembanganAdapter(this,R.layout.list_perkembangan,contentHistory);
            level1.setAdapter(perkembanganAdapter);

        } else {
            perkembanganAdapter.notifyDataSetChanged(); // Not really needed if updating when checked
        }
    }
}

演示结果

第一次运行时:-

Second Run row 2 勾选然后重新启动

Third Run all 3 checkeck boxes reversed and then restarted