Change it to

...
String input;
do
{
    input = scan.next();
    if(input.equals("enter") || input.equals("Enter"))
    {
        System.out.println("You have entered the house.");
    }
...

Use a while loop above input line as:

 while(true)

And, use if condition to break.

if(year == 0)
    break;

Also, condition for leap year is wrong in your code. It should be:

if((year % 100 == 0 && year % 400 == 0) || (year % 4 == 0 && year % 100 != 0))
    //its a leap year
else
    //its not

PS: As in comments, I'll give a complete code:

import java.util.*;

public class Task10 {

public static void main(String[] args) {
    System.out.println("Enter a year to check if it is a leap year");
    while(true){
    Scanner input = new Scanner(System.in);
        int year = input.nextInt();
        if(year == 0)
            break;
        if((year % 100 == 0 && year % 400 == 0) || (year % 4 == 0 && year % 100 != 0))
            System.out.println(year + " is a leap year");
        else
            System.out.println(year + " is not a leap year");
    }
}

}

Let's try to be magician, and guess what you want:

public static void main(String[] args) {
    final Scanner in = new Scanner(System.in);
    int methodNumber;
    do {
        System.out.print("Method number (0 to quit): ");
        methodNumber = in.nextInt();

        switch (methodNumber) {
        case 1:
            method1();
            break;
        case 2:
            method2();
            break;
        case 3:
            method3();
            break;
        case 4:
            method4();
            break;
        }

    } while (methodNumber!=0);
}

public static void method1() {
    System.out.println("Method 1");
}

public static void method2() {
    System.out.println("Method 2");
}

public static void method3() {
    System.out.println("Method 3");
}

public static void method4() {
    System.out.println("Method 4");
}

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