Dilemma with Toast message

Question

I'm developing a simple app, the user will have to fill in their name, email, rate the app, and describe their experience(optional). If their is an empty field(name and email), an error message will pop up. I'm having trouble with Toast.LENGTH_LONG() at the end of the code. It keep saying 'method call expected'.

MainActivity.java

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

    Spinner spinner = (Spinner) findViewById(R.id.spinner1);

    //Create an array adapter
    ArrayAdapter<CharSequence> adapter = ArrayAdapter.createFromResource(this, R.array.rate_array, android.R.layout.simple_spinner_dropdown_item);

    //Specify the layout for the drop down menu 
    adapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);

    //Apply the adapter to the spinner
    spinner.setAdapter(adapter);

    final EditText name = (EditText) findViewById(R.id.Name);
    final EditText e_mail = (EditText) findViewById(R.id.email);
    final Button submit = (Button) findViewById(R.id.submit);

    submit.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            if(name.getText().length() == 0){
                name.setError("Please fill in your name");
            }
            else{
                if(e_mail.getText().length() == 0){
                    e_mail.setError("Please fill in your email");
                }
                else{
                    Toast.makeText(this, "Validation successful", 
                    Toast.LENGTH_LONG()).show();
                }
            }
        }
    });

 }
}

activity_main.xml

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"

xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context="com.example.infinite_space.myapplication.MainActivity"
android:orientation="vertical"
android:weightSum="1">

<TextView
    android:id="@+id/textView"
    android:layout_width="292dp"
    android:layout_height="37dp"
    android:text="Enter Feedback details to b sent to the developers"
    android:visibility="visible"
    tools:layout_editor_absoluteX="16dp"
    tools:layout_editor_absoluteY="16dp"
    android:layout_weight="0.18" />

<EditText
    android:id="@+id/Name"
    android:layout_width="fill_parent"
    android:layout_height="wrap_content"
    android:ems="10"
    android:hint="Your Name"
    android:inputType="textPersonName"
    tools:layout_editor_absoluteX="16dp"
    tools:layout_editor_absoluteY="67dp" />

<Spinner
    android:id="@+id/spinner1"
    android:layout_width="fill_parent"
    android:layout_height="35dp"
    android:background="@android:drawable/btn_dropdown"
    android:spinnerMode="dropdown"
    tools:layout_editor_absoluteY="176dp"
    tools:layout_editor_absoluteX="16dp"
    android:prompt="@string/rate_level"
    android:entries="@array/rate_array" />

<EditText
    android:id="@+id/email"
    android:layout_width="fill_parent"
    android:layout_height="wrap_content"
    android:ems="10"
    android:hint="Your email"
    android:inputType="textEmailAddress"
    tools:layout_editor_absoluteX="16dp"
    tools:layout_editor_absoluteY="122dp" />

<EditText
    android:id="@+id/details"
    android:layout_width="fill_parent"
    android:layout_height="103dp"
    android:ems="10"
    android:hint="Details..."
    android:inputType="text"
    tools:layout_editor_absoluteX="16dp"
    tools:layout_editor_absoluteY="227dp" />

<CheckBox
    android:id="@+id/checkBox"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:text="Would you like an email respond ?"
    tools:layout_editor_absoluteX="0dp"
    tools:layout_editor_absoluteY="343dp" />

<Button
    android:id="@+id/submit"
    android:layout_width="fill_parent"
    android:layout_height="wrap_content"
    android:text="Send Feedback"
    tools:layout_editor_absoluteX="0dp"
    tools:layout_editor_absoluteY="385dp" />
</LinearLayout>

Answer 1

Toast.LENGTH_LONG is a (constant) field and not a method. Change LENGTH_LONG() to LENGTH_LONG .

Answer 2

Should be either LENGTH_LONG for a long period of time or LENGTH_SHORT for a short period of time. Get rid of the () after LENGTH_LONG .

Answer 3

尝试这个 ：

 Toast.makeText(this, "Validation successful",Toast.LENGTH_LONG).show();