> package com.example.mytest;
> import androidx.appcompat.app.AppCompatActivity;
> 
> import android.icu.text.SimpleDateFormat;
> import android.os.Bundle;
> import android.widget.TextView;
> 
> import java.util.Arrays;
> import java.util.Date;
> import java.util.Locale;
> 
> public class MainActivity extends AppCompatActivity {
>    @Override
> protected void onCreate(Bundle savedInstanceState) {
> super.onCreate(savedInstanceState);
> setContentView(R.layout.activity_main);
>     }
> 
> PrintScreen();
>  
> public void PrintScreen() {
> System.out.println("This is a test");    
>     }
> }

如何在MainActivity（Android Studio海豚）中调用公共void方法PrintScreen（）？它不接受上述代码。谢谢