ANDROID STUDIO > Sqlite、Listview 和 Onclick 基本示例

Question

在阅读了一些教程之后，我正在尝试构建我的第一个应用程序。我正在使用的是这个:http://instinctcoder.com/android-studio-sqlite-database-example/

但是在他的应用中，这个人通过一个中间步骤来列出 sql 记录。

我希望我的应用执行以下操作:

我的 Activity

“添加播放器”按钮，单击后会显示 DisplayMessageActivity，我可以在其中将名称保存在数据库中

显示消息 Activity

名称的 EditText，三个按钮(删除、更新、关闭)(当点击删除时，我被带回 MyActivity)(点击更新时，我停留在 DisplayMessageActivity 上)(当点击关闭时，我被带回 MyActivity))

我设法构建了它，两者之间的导航都有效，并且数据库插入效果很好。

保存名称时，我返回到第一个 Activity ，但出现的列表未使用新添加的名称进行更新。

这是我的 activity_main.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:id="@+id/swipe_container"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="horizontal"
    tools:context="tab.sqltesting.com.myapplication.MyActivity">

    <Button
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Add Player"
        android:id="@+id/addPlayer"
        android:onClick="addPlayer" />

<ListView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:id="@android:id/list"
        android:layout_centerHorizontal="true"
        android:layout_alignParentTop="true"
        android:layout_above="@+id/btnAdd" />

</LinearLayout>

这是我的 activity_main.java

public class MyActivity extends ListActivity implements android.view.View.OnClickListener{

    Button addPlayer;
    TextView players_Id;

    @Override
    protected void onCreate(Bundle savedInstanceState) {

        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_my);


        PlayersRepo repo = new PlayersRepo(this);
        ArrayList<HashMap<String, String>> playersList = repo.getPlayersList();

                if (playersList.size() != 0) {

                    ListView lv = getListView();

                    lv.setOnItemClickListener(new AdapterView.OnItemClickListener() {

                        @Override
                        public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
                            players_Id = (TextView) view.findViewById(R.id.players_Id);
                            String playersId = players_Id.getText().toString();
                            Intent objIndent = new Intent(getApplicationContext(), DisplayMessageActivity.class);
                            objIndent.putExtra("players_Id", Integer.parseInt(playersId));
                            startActivity(objIndent);
                        }

                    });

                    ListAdapter adapter = new SimpleAdapter(MyActivity.this, playersList, R.layout.list_players_view, new String[]{"id", "name"}, new int[]{R.id.players_Id, R.id.players_name});
                    setListAdapter(adapter);

                } else {

                    Toast.makeText(this, "No Player!", Toast.LENGTH_SHORT).show();

                }

        addPlayer = (Button) findViewById(R.id.addPlayer);
        addPlayer.setOnClickListener(this);

    }


    @Override
    public void onClick(View view) {

        if (view == findViewById(R.id.addPlayer)) {

            Intent intent = new Intent(this, DisplayMessageActivity.class);
            startActivity(intent);
        }

    }

我想请求你的帮助，帮助我理解我做错了什么。

请接受我对我的误解表示歉意。

非常感谢!

bat

Answer 1

在添加 OnResume() 方法中找到解决方案。这是我最后的 Activity 课:

package tab.sqltesting.com.myapplication;

public class MyActivity extends ListActivity implements android.view.View.OnClickListener{

    Button addPlayer;
    TextView players_Id;

    @Override
    protected void onCreate(Bundle savedInstanceState) {

        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_my);

        addPlayer = (Button) findViewById(R.id.addPlayer);
        addPlayer.setOnClickListener(this);

    }

    @Override
    public void onClick(View view) {

        if (view == findViewById(R.id.addPlayer)) {

            Intent intent = new Intent(this, DisplayMessageActivity.class);
            startActivity(intent);
        }
    }

    @Override
    public void onResume() {

        super.onResume();
        PlayersRepo repo = new PlayersRepo(this);
        ArrayList<HashMap<String, String>> playersList = repo.getPlayersList();

        if (playersList.size() != 0) {

            ListView lv = getListView();

            lv.setOnItemClickListener(new AdapterView.OnItemClickListener() {

                @Override
                public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
                    players_Id = (TextView) view.findViewById(R.id.players_Id);
                    String playersId = players_Id.getText().toString();
                    Intent objIndent = new Intent(getApplicationContext(), DisplayMessageActivity.class);
                    objIndent.putExtra("players_Id", Integer.parseInt(playersId));
                    startActivity(objIndent);
                }

            });

            ListAdapter adapter = new SimpleAdapter(MyActivity.this, playersList, R.layout.list_players_view, new String[]{"id", "name"}, new int[]{R.id.players_Id, R.id.players_name});
            setListAdapter(adapter);

        } else {

            Toast.makeText(this, "No Player!", Toast.LENGTH_SHORT).show();

        }
    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        // Inflate the menu; this adds items to the action bar if it is present.
        getMenuInflater().inflate(R.menu.my, menu);
        return true;
    }

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        // Handle action bar item clicks here. The action bar will
        // automatically handle clicks on the Home/Up button, so long
        // as you specify a parent activity in AndroidManifest.xml.
        int id = item.getItemId();
        if (id == R.id.action_settings) {
            return true;
        }
        return super.onOptionsItemSelected(item);
    }
}