小编War*_*Lyn的帖子

我是初学Android开发者,这是我的第一个项目.我必须将ViewData.java上的ListView中的选定数据显示到EntryTO.java上的ListView.首先,我得到一个错误nullPointerException.我尝试检测if函数的问题在哪里.并出现该错误."对于参数类型long,null,运算符!=未定义"

这是我尝试从listview ViewData.java获取数据时的代码

ListView lv = (ListView) findViewById(android.R.id.list);
          lv.setOnItemClickListener(new AdapterView.OnItemClickListener(){
          @Override
          public void onItemClick(final AdapterView<?> adapter, View v, int pos, final long id) {
          final Dialog dialog = new Dialog(ViewData.this);
          dialog.setContentView(R.layout.dialog_view);
          dialog.setTitle("Masukkan Qty");
          dialog.show();
          final product b = (product) getListAdapter().getItem(pos);
          edtqty = (EditText) dialog.findViewById(R.id.edtqty);
          buttonok = (Button) dialog.findViewById(R.id.buttonok);
          buttonok.setOnClickListener(new OnClickListener(){
              @Override
              public void onClick(View v) {
              switchToEdit(b.getId());
              Toast.makeText(ViewData.this, "Ambil product\n"+ b.getId() +"\n"+ b.getname() +"\n"+ b.getbrand()
              + edtqty.getText().toString(), Toast.LENGTH_LONG).show();
              dialog.dismiss();
                   };
             });
          }
      });
  public void switchToEdit(long id){
      product b = …