Android：從列表中添加和刪除項目到列表視圖

Question

我正在構建棋盤遊戲的計算器應用程序。 應用程序包含玩家可用的所有土地的列表，應用程序應該能夠添加和刪除玩家列表中的物品。

注意：應用程序應根據玩家手中的土地來計算玩家的利潤。

Player View Lands View 我希望能夠從土地的土地名單從播放器中點擊刪除按鈕時添加到球員，當上添加按鈕，用戶點擊刪除的土地。基於每個列表中的選定項目。

注：我使用的是相同的適配器列表中播放的項目和土地查看

public class DetailsActivity extends AppCompatActivity { 

private ListView ProjectsLV; 
private ProjectAdapter Adapter; 


@Override 
protected void onCreate(Bundle savedInstanceState) { 
    super.onCreate(savedInstanceState); 
    setContentView(R.layout.activity_details); 
    Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar); 
    setSupportActionBar(toolbar); 

    FloatingActionButton add_fab = (FloatingActionButton) findViewById(R.id.add_fab); 
    add_fab.setOnClickListener(new View.OnClickListener() { 
     @Override 
     public void onClick(View view) { 
      Snackbar.make(view, "Add Project", Snackbar.LENGTH_LONG) 
        .setAction("Action", null).show(); 
     } 
    }); 

    FloatingActionButton remove_fab = (FloatingActionButton) findViewById(R.id.remove_fab); 
    remove_fab.setOnClickListener(new View.OnClickListener() { 
     @Override 
     public void onClick(View view) { 
      Snackbar.make(view, "Remove Projects", Snackbar.LENGTH_LONG) 
        .setAction("Action", null).show(); 
     } 
    }); 

    Player Player = (Player)getIntent().getSerializableExtra("Player"); 

    ArrayList<Project> Projects = (ArrayList<Project>) getIntent().getSerializableExtra("Projects"); 
    Adapter = new ProjectAdapter(getApplicationContext(), Player.getProjects()); 

    ProjectsLV = (ListView)findViewById(R.id.ProjectsListView); 
    ProjectsLV.setAdapter(Adapter); 
} 

}

Answer 1

我說就怎麼做它的一些線，我自己的風格，你可以按照相同的方式來實現你想要的，但我會詳細解釋發生了什麼。 首先我創建了一個字段projectList，這樣我就可以在課程內部的任何地方訪問它，並且在添加或刪除此列表中的項目之後，您只需調用適配器上的notifyDataSetChange()即可更新您擁有的列表視圖。我希望這是夠好的。

public class DetailsActivity extends AppCompatActivity { 
private List<Project> projectsList; 
private ListView ProjectsLV; 
private ProjectAdapter Adapter; 

@Override 
protected void onCreate(Bundle savedInstanceState) { 
    super.onCreate(savedInstanceState); 
    setContentView(R.layout.activity_details); 
    Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar); 
    setSupportActionBar(toolbar); 
    FloatingActionButton add_fab = (FloatingActionButton) findViewById(R.id.add_fab); 


    FloatingActionButton remove_fab = (FloatingActionButton) findViewById(R.id.remove_fab); 


    Player Player = (Player)getIntent().getSerializableExtra("Player"); 

    ArrayList<Project> Projects = (ArrayList<Project>) getIntent().getSerializableExtra("Projects"); 
    projectsList = Plyaer.getProjects(); 
    Adapter = new ProjectAdapter(getApplicationContext(), projectsList); 

    ProjectsLV = (ListView)findViewById(R.id.ProjectsListView); 
    ProjectsLV.setAdapter(Adapter); 
    add_fab.setOnClickListener(new View.OnClickListener() { 
     @Override 
     public void onClick(View view) { 
      Snackbar.make(view, "Add Project", Snackbar.LENGTH_LONG) 
        .setAction("Action", null).show(); 
      // create the new project and call the addProjectToList method; 
      prjectsList = addProjectToList(projectsList,project); 
      Adapter.notifyDataSetChange(); 
     } 
    }); 
    remove_fab.setOnClickListener(new View.OnClickListener() { 
     @Override 
     public void onClick(View view) { 
      Snackbar.make(view, "Remove Projects", Snackbar.LENGTH_LONG) 
        .setAction("Action", null).show(); 
      // choose the project to remove and call the removeProjectFromList method; 
      removeProjectFromList(projectsList,project); 
      Adapter.notifyDataSetChange(); 
     } 
    }); 

} 
    private List<Project> addProjectToList(List<Project> projectsList,Project project){ 
     projectsList.add(project); 
     return projectsList; 
    } 
    private List<Project> removeProjectFromList(List<Project> projectsList,Project project){ 
     projectsList.remove(project); 
     return projectsList; 
    } 
} 

Answer 2

更新的類

public class DetailsActivity extends AppCompatActivity { 

private ListView ProjectsLV; 
private ProjectAdapter Adapter; 
private ArrayList<Project> PlayerProjectList; 
private Project selectedProject; 
private ArrayList<Project> Projects; 
private Player Player; 

@Override 
protected void onCreate(Bundle savedInstanceState) { 
    super.onCreate(savedInstanceState); 
    setContentView(R.layout.activity_details); 
    Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar); 
    setSupportActionBar(toolbar); 

    FloatingActionButton add_fab = (FloatingActionButton) findViewById(R.id.add_fab); 
    FloatingActionButton remove_fab = (FloatingActionButton) findViewById(R.id.remove_fab); 

    Player = (Player)getIntent().getSerializableExtra("Player"); 

    Projects = (ArrayList<Project>) getIntent().getSerializableExtra("Projects"); 
    PlayerProjectList = Player.getProjects(); 

    Adapter = new ProjectAdapter(getApplicationContext(), PlayerProjectList); 

    ProjectsLV = (ListView)findViewById(R.id.ProjectsListView); 
    ProjectsLV.setAdapter(Adapter); 

    ProjectsLV.setOnItemClickListener(new AdapterView.OnItemClickListener() { 
     @Override 
     public void onItemClick(AdapterView<?> parent, View view, int position, long id) { 
      selectedProject =(Project) (ProjectsLV.getItemAtPosition(position)); 
     } 
    }); 

    add_fab.setOnClickListener(new View.OnClickListener() { 
     @Override 
     public void onClick(View view) { 
      Snackbar.make(view, "Add Project", Snackbar.LENGTH_LONG) 
        .setAction("Action", null).show(); 
      // create the new project and call the addProjectToList method; 
      PlayerProjectList = addProjectToList(PlayerProjectList, selectedProject); 
      Adapter.notifyDataSetChanged(); 
     } 
    }); 

    remove_fab.setOnClickListener(new View.OnClickListener() { 
     @Override 
     public void onClick(View view) { 
      Snackbar.make(view, "Remove Projects", Snackbar.LENGTH_LONG) 
        .setAction("Action", null).show(); 
      // choose the project to remove and call the removeProjectFromList method; 
      removeProjectFromList(PlayerProjectList, selectedProject); 
      Adapter.notifyDataSetChanged(); 
     } 
    }); 
} 

private ArrayList<Project> addProjectToList(ArrayList<Project> projectsList,Project project){ 
    projectsList.add(project); 
    return projectsList; 
} 
private ArrayList<Project> removeProjectFromList(ArrayList<Project> projectsList,Project project){ 
    projectsList.remove(project); 
    return projectsList; 
} 

}