Does it compile? questions in java

Q1.java

public abstract class A {
    
    private int x = 7;

    public A(int x) {
        this.x = x;
        System.out.println("A::A, x=" + x);
    }

    public int getX() {
        return x;
    }
}

public class Main {

    public static void main(String[] args) {
        A a = new A(9);
        System.out.println(a.getX());
    }
}

Q10.java

class Swapper {
    public static void swap1(int a, int b) {
        int temp = a;
        a = b;
        b = temp;
    }

    public static void swap2(int[] a, int[] b) {
        if (a.length > 0 && b.length > 0) {
            int temp = a[0];
            a[0] = b[0];
            b[0] = temp;
        }
    }
}

public class Main {    
    public static void main(String[] args) {    
        int a = 1;
        int b = 2;
        int[] c = {a};
        int[] d = {b};   
        Swapper.swap1(a, b);
        Swapper.swap2(c, d);
        System.out.println("a=" + a + ", b=" + b + ", c=[" + c[0] +"], d=[" + d[0] +"]");
    }
}

Q2.java

public class A {    
    private int x = 7;

    public A(int x) {
        // notice this line...
        x = x;

        System.out.println("A::A, x=" + x);
    }

    public int getX() {
        return x;
    }
}

public class Main {

    public static void main(String[] args) {
        A a = new A(9);
        System.out.println(a.getX());
    }
}

Q3.java

public abstract class A {
    
    protected int x = 7;

    public A(int x) {
        this.x = x;
        System.out.println("A::A, x=" + x);
    }

    public int getX() {
        return x;
    }
}

public class B extends A {

    public int getX() {
        return x + 2;
    }
}

public class Main {

    public static void main(String[] args) {
        B b = new B();
        System.out.println(b.getX());
    }
}

Q4.java

public abstract class A {
    
    private int x;

    public A(int x) {
        this.x = x;
        System.out.println("A::A, x=" + x);
    }

    public int getX() {
        return x;
    }
}

public class B extends A {

    public B() {
        super(7);
        System.out.println("B constructor called");
    }

    public int getX() {
        return x + 2;
    }
}

public class Main {

    public static void main(String[] args) {
        B b = new B();
        System.out.println(b.getX());
    }
}

Q5.java

public abstract class A {
    
    private int x;

    public A(int x) {
        this.x = x;
        System.out.println("A::A, x=" + x);
    }

    public int getX() {
        return x;
    }
}

public class B extends A {

    public B() {
        super(7);
        System.out.println("B constructor called");
    }

    public int getX() {
        return super.getX() + 2;
    }
}

public class C extends B {
    public int getX() {
        return 20;
    }
}

public class Main {

    public static void main(String[] args) {
        int size = 2;

        A[] arr = new A[size];

        arr[0] = new B();
        arr[1] = new C();

        for (int i = 0; i < size; i++) {
            System.out.println(arr[i].getX());
        }
    }
}

Q6.java

public abstract class A {

    protected int num;

    public A(int x) {
        num = x;
        System.out.println("A: num=" + x);
    }

    public String toString() {
        return getClass().getName() + ": " + num + ", " + fruit();
    }
        
    public abstract String fruit();
}

public class B extends A {

    public B(int bla) {
        super(bla + 1);
        System.out.println("B: bla=" + bla);
    }

    public String fruit() {
        return "Banana";
    }
}

public class C extends A {

    private String fakeFruit;

    public C(A other) {
        super(other.num * 2);
        fakeFruit = other.toString();
        System.out.println("C: initialized from " + other);
    }

    public String fruit() {
        return fakeFruit;
    }
}

public class Main {

    public static void main(String[] args) {
        A a1 = new B(8);
        A a2 = new C(a1);

        System.out.println(a1);
        System.out.println(a2);
    }
}

Q7.java

public class Main {
    public static void main(String[] args) {
        final int a = 10;
        double b = a;
        char c = a;
        a += 5;
        System.out.println("a=" + a + ", b=" + b + ", c=" + c);
    }
}

Q8.java

import java.util.Arrays;     
     
public class Main {     
    public static void main(String[] args) {     
        int[] a = new int[5];     
        final int SIZE = 10;     
        for (int i = 0; i < SIZE; i++) {     
            a[i] = i + 1;     
        }     
        System.out.println(Arrays.toString(a));     
    }     
}     

Q9.java

import java.util.Arrays;    
    
public class Main {    
    private static void increaseArray(int[] arr) {
        for (int i = 0; i < arr.length; i++) {    
            arr[i] += 1;    
        }    
    }    
    
    public static void main(String[] args) {    
        int[] arr1 = {1, 2, 3, 4};   
        int[] arr2 = new int[3];    
        increaseArray(arr1);    
        increaseArray(arr2);    
        System.out.println(Arrays.toString(arr1));    
        System.out.println(Arrays.toString(arr2));    
    }    
}