Question

这是我的ListView代码，我需要按ID而不是按位置选择元素。任何人都可以帮我解决这个问题，我尝试过使用位置但是当我删除listView时，一个新的ListView进入了我不想要的位置！

public class MainActivity extends AppCompatActivity {

// The data to show
List<Planet> planetsList = new ArrayList<Planet>();
PlanetAdapter aAdpt;

@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

    initList();

    // We get the ListView component from the layout
    ListView lv = (ListView) findViewById(R.id.listView);


    // This is a simple adapter that accepts as parameter
    // Context
    // Data list
    // The row layout that is used during the row creation
    // The keys used to retrieve the data
    // The View id used to show the data. The key number and the view id must match
    //aAdpt = new ArrayAdapter<String>(this, android.R.layout.simple_list_item_1, android.R.id.text1, planetsList);
    aAdpt = new PlanetAdapter(planetsList, this);
    lv.setAdapter(aAdpt);

    // React to user clicks on item
    lv.setOnItemClickListener(new AdapterView.OnItemClickListener() {

        public void onItemClick(AdapterView<?> parentAdapter, View view, int position,
                                long id) {



            if (position == 0) {
                Toast.makeText(MainActivity.this, "Jello", Toast.LENGTH_SHORT).show();
                Intent intent = new Intent(getApplicationContext(),PhotoActivity.class);
                startActivity(intent);
            }
            if (position == 1) {
                Toast.makeText(MainActivity.this, "Jello", Toast.LENGTH_SHORT).show();
            }


        }
    });

    // we register for the contextmneu
    registerForContextMenu(lv);
}


// We want to create a context Menu when the user long click on an item
@Override
public void onCreateContextMenu(ContextMenu menu, View v,
                                ContextMenuInfo menuInfo) {

    super.onCreateContextMenu(menu, v, menuInfo);
    AdapterContextMenuInfo aInfo = (AdapterContextMenuInfo) menuInfo;

    // We know that each row in the adapter is a Map
    Planet planet =  aAdpt.getItem(aInfo.position);

    menu.setHeaderTitle("Options for " + planet.getName());
    menu.add(1, 2, 2, "Delete");

}




// This method is called when user selects an Item in the Context menu
@Override
public boolean onContextItemSelected(MenuItem item) {
    int itemId = item.getItemId();
    AdapterContextMenuInfo aInfo = (AdapterContextMenuInfo) item.getMenuInfo();
    planetsList.remove(aInfo.position);
    aAdpt.notifyDataSetChanged();
    return true;
}


private void initList() {
    // We populate the planets

    planetsList.add(new Planet("Work Gallery", 10));
    planetsList.add(new Planet("Buildings Gallery", 20));
    planetsList.add(new Planet("Miscellaneous", 30));


}


// Handle user click
public void addPlanet(View view) {
    final Dialog d = new Dialog(this);
    d.setContentView(R.layout.dialog);
    d.setTitle("Add planet");
    d.setCancelable(true);

    final EditText edit = (EditText) d.findViewById(R.id.editTextPlanet);
    Button b = (Button) d.findViewById(R.id.button1);
    b.setOnClickListener(new View.OnClickListener() {

        public void onClick(View v) {
            String planetName = edit.getText().toString();
            MainActivity.this.planetsList.add(new Planet(planetName, 0));
            MainActivity.this.aAdpt.notifyDataSetChanged(); // We notify the data model is changed
            d.dismiss();
        }
    });

    d.show();
}

}

Planet.java

public class Planet {

private String name;
private Integer distance;
private String descr;
private int index;



public Planet(String name, Integer distance) {
    this.name = name;
    this.distance = distance;
}

public Planet(String name, String descr) {
    this.name = name;
    this.descr = descr;
}

public Planet(String name, Integer distance, String descr, int idImg) {
    this.name = name;
    this.distance = distance;
    this.descr = descr;
    this.index = idImg;
}


public String getName() {
    return name;
}
public void setName(String name) {
    this.name = name;
}
public Integer getDistance() {
    return distance;
}
public void setDistance(Integer distance) {
    this.distance = distance;
}
public int getIdImg() {
    return index;
}
public void setIdImg(int idImg) {
    this.index = idImg;
}

}

Answer 1

假设你，

想要通过该对象的ID访问Planet Object而不是您的位置
在Plannet班级

如果是的话，

你可以做点什么，

if (planetsList.get(position).getId() == 0) {

编辑：

在您的Planet课程中

public Planet(String name, Integer distance, Integer index) {
    this.name = name;
    this.distance = distance;
    this.index= index;
}

并且还为您的类变量index设置了getter和setter。

在你的代码中，

    planetsList.add(new Planet("Work Gallery", 10,0));
    planetsList.add(new Planet("Buildings Gallery", 20,1));
    planetsList.add(new Planet("Miscellaneous", 30,2));

Answer 2

您也可以在适配器中使用方法view.setTag（）。把id放在视野中。并在OnClickListener中获取它。例如：

public View getView(int position, View convertedView, ViewGroup parent) {
    converterView = createView();
    convertedView.setTag(items.get(position).getId())
}

lv.setOnClickListener(new OnclickListener -> int id = (Integer) view.getId());

按ID选择ListView中的项目

2 个答案: