为什么我要得到期望的表达式fab.setOnClickListener（View？

Question

为什么我不能在fab.setOnClickListener(View方法的onCreate内部创建弹出对话框？

是因为语法吗？我是否缺少表情？ 我的代码是否已经过时，因为我的老师是老课程？

      public class MainActivity extends AppCompatActivity {

        private AlertDialog.Builder dialogBuilder;
        private AlertDialog dialog;
        private EditText groceryItem;
        private EditText getGroceryItem;
        private EditText quantity;
        private Button saveButton;

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

            FloatingActionButton fab = findViewById(R.id.fab);
       // === error appears on the next line ===
            fab.setOnClickListener(View,  

            createPopupDialog());

        }

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

            //noinspection SimplifiableIfStatement
            if (id == R.id.action_settings) {
                return true;
            }

            return super.onOptionsItemSelected(item);
        }


         private void createPopupDialog() {

            dialogBuilder = new AlertDialog.Builder(this);
            View view = getLayoutInflater().inflate(R.layout.popup, null);
            groceryItem = view.findViewById(R.id.groceryItem);
            quantity = view.findViewById(groceryQty);
            saveButton = view.findViewById(R.id.saveButton);

            dialogBuilder.setView(view);
            dialog = dialogBuilder.create();
            dialog.show();



        }


    }

Answer 1

您没有在$fso = New-Object -com "Scripting.FileSystemObject" $Versionarray = (13..20) $folder = $fso.GetFolder("$env:USERPROFILE\appdata\local\Microsoft\OneDrive") foreach ($subfolder in $folder.SubFolders) { If ($subfolder.Name -match "$Versionarray") { remove-item $subfolder.Path -Verbose } } 中传递正确的参数。
像这样创建侦听器：

setOnClickListener()

Answer 2

我认为您想使用lambda表达式。如果是这样，这是正确的语法：

fab.setOnClickListener((View v) -> {
    createPopupDialog();
});