Java variables and shadowing

What happens when there is a local variable with the same name as an instance or static variable?

Here is some sample code to illusrate what happens:

package ScopeVariables;

import absolutely.nothing_else.can.go.here;  //only imports can be outside a class

public class BigMainClass {
	
	//Global variables
	//*** DO NOT NEED TO BE INITIALIZED.
	//*** CAN BE ACCESSED FROM ANYWHERE IN THIS CLASS
	static String president = "Trump";
	static int myStaticInt;
	
	String day = "Monday";
	int myInstanceInt;
	int speed = 8;
		
	//static methods
	static void myStaticMethod() {
		System.out.println("I'm a static method.");
	}
	
	//instance methods
	void myInstanceMethod(int qwerty) {
		myInstanceInt = qwerty;
		System.out.println("I'm instance method #" + myInstanceInt);
	}
	
	void move() {
		speed ++;
	}
	
	//constructors
	BigMainClass() {
		System.out.println("I am a constructor for BigMainClass");
	}
	
	//main
	public static void main(String[] args){ //also a static method
		
		System.out.println("myStaticInt is " + myStaticInt);
		
		//myInstanceInt = 7; //ERROR: because: cannot access instance things from a static thing.
		
		BigMainClass bm1 = new BigMainClass();
		bm1.myInstanceMethod(5);
		Child cc = new Child();
		
//		System.out.println("speed = " + bm1.speed);
		bm1.move();
		cc.move();
		System.out.println("speed = " + cc.speed);
		System.out.println("speed = " + bm1.speed);
		
		new MiniClass().miniMethod();
		
		System.out.println("myStaticInt is " + myStaticInt);
		
	
	
		//shadowing static variables
		System.out.println("\n\nThe president is " + president);		//TRUMP
		String president = "Clinton"; //now president is shadowed; I've created a local variable with the same name
		System.out.println("The president is " + president);	`		//CLINTON
		System.out.println("No, The president is " + BigMainClass.president);	//TRUMP
	
	
		//shadowing instance variables
		//System.out.println("Today is " + day); // ERROR Must do this in an instance context ...
		
		bm1.shadow();
		
		//OTHER ERRORS: Local variables
		int fingers;
		//fingers = fingers + 2;	//ERROR: fingers is not initialized.
		
		MiniClass zeta;
		//zeta.miniMethod();  //ERROR: null pointer error if zeta is global variable; uninitialized error if it is a local variable
		
	}
 
	
	void shadow() {
		System.out.println("\nA static variable: " + president);
		
		System.out.println("Today is " + day);
		day = "--unknown--";		
		System.out.println("Today is " + day);
		String day = "Tuesday";  //now day is shadowed
		System.out.println("No, today is " + day);
		System.out.println("Actually today is " + this.day);
	}
	
}

class MiniClass {
	
	void miniMethod() {
		
		//since the variable is not private, I can access it in another class in the same package.
		BigMainClass.myStaticInt++;
	}
}


class Child extends BigMainClass{
	Child() {
		speed = super.speed + 6;
		
	}
}