Android - Updating list view on spinner selection

问题:

I am trying to update a list view, when I select on an item in spinner, the code works but no output is generated. I cannot figure out the bug.On every click on the item in spinner I want to view different list.

Spinner spinner;
String path[] = {"Laptops","DesktopPC","Tablets","Add-Ons","Gaming"};
String Laptops[] = {"Dell","Hp","Apple"};
ListView lstView;


lstView = (ListView) findViewById(R.id.listView1);

ArrayAdapter<String> adapter = new ArrayAdapter<String> (Category.this, android.R.layout.simple_spinner_item, path );
spinner = (Spinner) findViewById(R.id.spinner1);
spinner.setAdapter(adapter);
spinner.setOnItemClickListener(new OnItemClickListener() {

    @Override
    public void onItemClick(AdapterView<?> arg0, View arg1,
            int arg2, long arg3) {
        // TODO Auto-generated method stub
        ArrayAdapter<String> lstAdapter = new ArrayAdapter<String>(getApplicationContext(), android.R.layout.simple_list_item_1, Laptops);
        lstView.setAdapter(lstAdapter);
        //lstView.refreshDrawableState();

    }
});

回答1:

Use OnItemSelectedListener and use a ArrayList<String>. Use the same for your adapter. Add items to arraylist and call notifyDataSetChanged on your adapter to refresh lsitview.

Also there is no need to initialize your adapter in the spinner selection listener.

Modify the below according to your requirement

 Spinner spinner;
        String path[] = {"Laptops","DesktopPC","Tablets","Add-Ons","Gaming"};
        ArrayList<String> list = new ArrayList<String>();
        String Laptops[] = {"Dell","Hp","Apple"};
        ListView lstView;
        ArrayAdapter<String> adapter,listadapter;
        public void onCreate(Bundle savedInstanceState) {
             super.onCreate(savedInstanceState);
             setContentView(R.layout.activity_main);
                lstView = (ListView) findViewById(R.id.listView1);
                for(int i=0;i<Laptops.length;i++)
                {
                    list.add(Laptops[i]);
                }
                adapter = new ArrayAdapter<String> (this, android.R.layout.simple_spinner_item,path);
                listadapter = new ArrayAdapter<String> (this, android.R.layout.simple_spinner_item,list);
                lstView.setAdapter(listadapter);
                spinner = (Spinner) findViewById(R.id.spinner1);
                spinner.setAdapter(adapter);
                spinner.setOnItemSelectedListener(new OnItemSelectedListener() {

                    @Override
                    public void onItemSelected(AdapterView<?> arg0, View arg1,
                            int arg2, long arg3) {
                        // TODO Auto-generated method stub
                        String s = spinner.getItemAtPosition(arg2).toString();
                        list.add(s);
                        listadapter.notifyDataSetChanged();
                    }

                    @Override
                    public void onNothingSelected(AdapterView<?> arg0) {
                        // TODO Auto-generated method stub

                    }
                });

            }

回答2:

Use notifying that data set has been changed instead of setting a new adapter.

// Inside Event callback
 path = Laptops; // This is how you change data set
 lstView.notifyDataSetChanged();

回答3:

Add notifyDataSetChanged() to adapter like below....

spinner.setOnItemClickListener(new OnItemClickListener() {

            @Override
            public void onItemClick(AdapterView<?> arg0, View arg1,
                    int arg2, long arg3) {
                // TODO Auto-generated method stub
                ArrayAdapter<String> lstAdapter = new ArrayAdapter<String>(getApplicationContext(), android.R.layout.simple_list_item_1, Laptops);
                lstView.setAdapter(lstAdapter);
                lstAdapter.notifyDataSetChanged();
                //lstView.refreshDrawableState();

            }
        });

回答4:

Use Spinner onitemSelectedListener instead of onItemClickListener

Try the following :

spinner.setOnItemSelectedListener(new OnItemSelectedListener() {
    @Override
    public void onItemSelected(AdapterView<?> parentView, View selectedItemView, int position, long id) {
        // your code here


  ArrayAdapter<String> lstAdapter = new ArrayAdapter<String>(getApplicationContext(), android.R.layout.simple_list_item_1, Laptops);
                    lstView.setAdapter(lstAdapter);
                    lstView.notifyDataSetChanged();
        }

    @Override
    public void onNothingSelected(AdapterView<?> parentView) {
        // your code here
    }

});