Given the following code, which of these constructors can be added to class B without causing a compile time error?

class A{
   int i;
   public A(int x) { this.i = x; }
}
class B extends A{
   int j;
   public B(int x, int y) { super(x);  this.j = y; }
}

1. B( ) { }
2. B(int y ) { j = y; }
3. B(int y ) { super(y*2 ); j = y; }
4. B(int y ) { i = y; j = y*2; }
5. B(int z ) { this(z, z); }

What will the following code print?
        int x = 1;
        int y = 2;
        int z = x++;
        int a = --y;
        int b = z--;
        b += ++z;

        int answ = x>a?y>b?y:b:x>z?x:z;
        System.out.println(answ);

1. 0
2. 1
3. 2
4. -1
5. -2
6. 3

Which statements about the following code are correct?

interface House{
  public default String getAddress(){
     return "101 Main Str";
  }
}

interface Bungalow extends House{
  public default String getAddress(){
     return "101 Smart Str";
  }
}

class MyHouse implements Bungalow, House{

}

public class TestClass {

  public static void main(String[] args) {
    House ci = new MyHouse();  //1
    System.out.println(ci.getAddress()); //2
  }
}

1. Code for interface House will cause compilation to fail.
2. Code for interface Bungalow will cause compilation to fail.
3. Code for class MyHouse will cause compilation to fail.
4. Line at //1 will cause compilation to fail.
5. Line at //2 will cause compilation to fail.
6. The code will compile successfully.

Consider the following code:

class Test{
  public static void main(String[] args){
    for (int i = 0; i < args.length; i++)   System.out.print(i == 0 ? args[i] : " " + args[i]);
  }
}

What will be the output when it is run using the following command:

java Test good bye friend!

1. good bye friend!
2. good good good
3. goodgoodgood
4. good bye
5. None of the above.

Which of the following statements will print true when executed?

1. System.out.println(Boolean.parseBoolean("true"));
2. System.out.println(new Boolean(null)));
   This will print false.
3. System.out.println(new Boolean()));
   This will not compile because Boolean class does not have a no-args constructor. Remember that no other wrapper class has a no-args constructor either. So new Integer(), or new Long() will also not compile.
4. System.out.println(new Boolean("true"));
   Case of the String parameter does not matter. As long as the String equals "true" after ignoring the case, it will be parsed as true.  However, if you have extra spaces, for example, " true" or "true ", it will be parsed as false.
5. System.out.println(new Boolean("trUE"));
   Case of the String parameter does not matter. As long as the String equals "true" after ignoring the case, it will be parsed as true.  However, if you have extra spaces, for example, " true" or "true ", it will be parsed as false.

You have written some Java code in MyFirstClass.java file. Which of the following commands will you use to compile and run it.
(Assume that the code has no package declaration.)

1. javac MyFirstClass.java
   javar MyFirstClass
2. javap MyFirstClass.java
   javar MyFirstClass.java
3. java MyFirstClass.java
   java MyFirstClass.class
4. javac MyFirstClass.java
   javar MyFirstClass.java
5. javac MyFirstClass.java
   java MyFirstClass

What will the following code print when run?

public class TestClass{
  public static long main(String[] args){
     System.out.println("Hello");
     return 10L;
  }
}

1. Hello
2. It will not print anything.
3. It will not compile
4. It will throw an Error at runtime.
5. None of the above.

Consider the following code:


interface Flyer{ String getName(); }

class Bird implements Flyer{
    public String name;
    public Bird(String name){
        this.name = name;
    }
    public String getName(){ return name; }
}

class Eagle extends Bird {
    public Eagle(String name){
        super(name);
    }
}

public class TestClass {
    public static void main(String[] args) throws Exception {
        Flyer f = new Eagle("American Bald Eagle");
        //PRINT NAME HERE
   }
}

Which of the following lines of code will print the name of the Eagle object?

1. System.out.println(f.name);
2. System.out.println(f.getName());
3. System.out.println(((Eagle)f).name);
4. System.out.println(((Bird)f).getName());
5. System.out.println(Eagle.name);
   name is not a static field in class Eagle.
6. System.out.println(Eagle.getName(f));
   This option doesn't make any sense.

What will the following program print when run?

public class ChangeTest {

    private int myValue = 0;
    
    public void showOne(int myValue){
        myValue = myValue;
    }
    
    public void showTwo(int myValue){
        this.myValue = myValue;
    }    
    public static void main(String[] args) {
        ChangeTest ct = new ChangeTest();
        ct.showTwo(200);
        System.out.println(ct.myValue);
        ct.showOne(100);
        System.out.println(ct.myValue);
    }
}

1. 0 followed by 100.
2. 100 followed by 100.
3. 0 followed by 200.
4. 100 followed by 200.
5. 200 followed by 200.
6. 200 followed by 100

What will the following program print?

public class TestClass{
  static boolean b;
  static int[] ia = new int[1];
  static char ch;
  static boolean[] ba = new boolean[1];
  public static void main(String args[]) throws Exception{
    boolean x = false;
    if( b ){
      x = ( ch == ia[ch]);
    }
    else x = ( ba[ch] = b );
    System.out.println(x+" "+ba[ch]);
  }
}

1. true true
2. true false
3. false true
4. false false
5. It will not compile.

Consider the following code:

class A{
 public XXX m1(int a){
   return a*10/4-30;
 }
}
class A2 extends A{
 public YYY m1(int a){
   return a*10/4.0;
 }
}

1. int, int
   a*10/4.0; generates a double so, A2's m1() cannot return an int. (It will need a cast otherwise: return (int) (a*10/4.0);)
2. int, double
   The return type should be same for overridden and overriding method.
3. double, double
   a*10/4-30; generates an int which can be returned as a double without any cast.
4. double, int
   The return type should be same for overridden and overriding method.
5. Nothing, they are simply not compatible.

What can be inserted in the code below so that it will print true when run?

public class TestClass{

   public static boolean checkList(List list, Predicate<List> p){
      return p.test(list);
   }
  
   public static void main(String[] args) {
      boolean b = //WRITE CODE HERE
      System.out.println(b);
   }
}

1. checkList(new ArrayList(), al -> al.isEmpty());
   The test method of Predicate returns a boolean. So all you need for your  body part in your lambda expression is an expression that returns a boolean.
   isEmpty() is a valid method of ArrayList, which returns true if there are no elements in the list. Therefore, al.isEmpty() constitutes a valid body for the lambda expression in this case.
2. checkList(new ArrayList(), ArrayList al -> al.isEmpty());
   You need to put the parameter list of the lambda expression in brackets if you want to use the parameter type. For example,
   checkList(new ArrayList(), (ArrayList al) -> al.isEmpty());
   Remember that specifying the parameter type is optional ( as shown in option 1) because the compiler can figure out the parameter types by looking at the signature of the abstract method of any functional interface (here, Predicate's test method).
3. checkList(new ArrayList(), al -> return al.size() == 0);
   You need to put the body withing curly braces if you want to use the return keyword. For example,
   checkList(new ArrayList(), al -> { return al.size() == 0; });
4. checkList(new ArrayList(), al -> al.add("hello"));
   The add method of ArrayList returns a boolean. Further, it returns true if the list is altered because of the call to add. In this case, al.add("hello") indeed alters the list because a new element is added to the list.

Given:
public class LoopTest {
    int k = 5;
    public boolean checkIt(int k){
        return k-->0?true:false;
    }
    public void printThem(){
        while(checkIt(k)){
            System.out.print(k);
        }
    }
    public static void main(String[] args) {
        new LoopTest().printThem();
    }
}
What changes should be made so that the program will print 54321?

1. No change is necessary.
   It will go in an infinite loop.
2. Replace System.out.print(k); with System.out.print(k--);
3. Replace System.out.print(k); with System.out.print(--k);
   It will print 43210.
4. Replace while(checkIt(k)) with while(checkIt(--k)).
   It will print 4321.
5. Replace return k-->0?true:false; with return this.k-->0?true:false;
   This will print 43210.

What will the following code print when compiled and run?


public class Discounter {
    static double percent; //1
    int offset = 10, base= 50; //2
    public static double calc(double value) {
        int coupon, offset, base; //3
        if(percent <10){ //4
            coupon = 15;
            offset = 20;
            base = 10;
        }
        return coupon*offset*base*value/100; //5
    }
    public static void main(String[] args) {
        System.out.println(calc(100));
    }
}

1. 3000
2. 3000.0
3. compilation error at //3
4. compilation error at //4
5. compilation error at //5
6. Exception at run time.

Consider the following code for the main() method:

public static void main(String[] args) throws Exception{
   int i = 1, j = 10;
   do {
      if (i++ > --j) continue;
   } while (i < 5);
   System.out.println("i=" + i + " j=" + j);
}

1. i=6 j=6
2. i=5 j=6
3. i=5 j=5
4. i=6 j=5
5. None of these.

Consider the following code:

class A {
    public void doA(int k) throws Exception {  // 0
        for(int i=0; i< 10; i++) {
            if(i == k) throw new Exception("Index of k is "+i); // 1
        }
    }
    public void doB(boolean f) { // 2
        if(f) {
            doA(15); // 3
        }
        else return;
    }
    public static void main(String[] args) { // 4
        A a = new A();
        a.doB(args.length>0); // 5
    }
 }

1. This will compile and run without any errors or exception.
2. This will compile if throws Exception is added at line //2
3. This will compile if throws Exception is added at line //4
4. This will compile if throws Exception is added at line //2 as well as //4
5. This will compile if  line marked // 1 is enclosed in a try - catch block.
   Even if // 1 is enclosed in a try block, the method still has throws Exception in its declaration, which will force the caller of this method to either declare Exception in its throws clause or put the call within a try block.

What will the following code print when compiled and run?

public class TestClass{
    
    public static void main(String[] args) {

        System.out.println(getMsg((char)10));

    }

    public static String getMsg(char x){
        String msg = "Input value must be ";
        msg = msg.concat("smaller than X");
        msg.replace('X', x);
        String rest = " and larger than 0";
        msg.concat(rest);
        return msg;
    }
}

1. Input value must be smaller than X and larger than 0
2. Input value must be smaller than 10 and larger than 0
3. Input value must be smaller than X
4. Input value must be smaller than 10

What will the following code print when run?

public class TestClass {
    public static void main(String[] args) throws Exception {
        
         boolean flag  = true;
         switch (flag){
             case true : System.out.println("true");
                 default: System.out.println("false");
         }
              
    }
}

1. It will not compile.
   A boolean cannot be used for a switch statement. It needs an integral type, an enum, or a String.
2. false
3. true
   false
4. Exception at run time.

How many objects have been created by the time the main method reaches its end in the following code?
public class Noobs {
    public Noobs(){
        try{
            throw new MyException();
        }catch(Exception e){
        }
    }
    public static void main(String[] args) {
        Noobs a = new Noobs();
        Noobs b = new Noobs();
        Noobs c = a;
    }
}
class MyException extends Exception{
    
}

1. 2
2. 3
3. 4
4. 5
5. 6

Which of the following are valid ways to create a LocalDateTime?

1. java.time.LocalDate.parse("2015-01-02");
   To create an instance of LocalDateTime, you need to use the methods in LocalDateTime class. Methods in LocalDate class create LocalDate instances. Similarly, methods in LocalTime class create LocalTime instances.
2. java.time.LocalDateTime.parse("2015-01-02");
   LocalDateTime requires date as well as time. Here, you just have a date in the input so it will throw a java.time.format.DateTimeParseException.
   java.time.LocalDateTime.parse("2015-01-02T17:13:50"); would be valid.
3. java.time.LocalDateTime.of(2015, 10, 1, 10, 10);
4. java.time.LocalDateTime.of(2015, "January", 1, 10, 10);
   All parameters should be ints. For the month argument, you can either pass the numbers 1 to 12  (and not 0 to 11) or use constants such as java.time.Month.JANUARY.

What will the following code print?

public class Test{
    public static void testInts(Integer obj, int var){
        obj = var++;
        obj++;
    }
    public static void main(String[] args) {
        Integer val1 = new Integer(5);
        int val2 = 9;
        testInts(val1++, ++val2);
        System.out.println(val1+" "+val2);
    }
}           

1. 10 9
2. 10 10
3. 6 9
4. 6 10
5. 5 11

Consider the following class...

class TestClass{
    void probe(Object x) { System.out.println("In Object"); } //3 

    void probe(Number x) { System.out.println("In Number"); } //2

    void probe(Integer x) { System.out.println("In Integer"); } //2
    
    void probe(Long x) { System.out.println("In Long"); } //4
    
    public static void main(String[] args){
        double a = 10; 
        new TestClass().probe(a); 
    }
}

1. In Number
2. In Object
3. In Long
4. In Integer
5. It will not compile.

What will the following code print when compiled and run?
class Baap{
    public int h = 4;
    public int getH(){
        System.out.println("Baap "+h); return h;
    }
}


public class Beta extends Baap{
    public int h = 44;
    public int getH(){
        System.out.println("Beta "+h); return h;
    }    
    public static void main(String[] args) {
        Baap b = new Beta();
        System.out.println(b.h+" "+b.getH());
        Beta bb = (Beta) b;
        System.out.println(bb.h+" "+bb.getH());
    }
}

1. Baap 44
   4 44
   Beta 44
   44 44
2. Beta 44
   4 44
   Baap 44
   44 44
3. Beta 44
   4 44
   Beta 44
   44 44
4. 4 44
   Beta 44
   44 44
   Beta 44
5. 44 44
   Beta 44
   4 44
   Beta 44
   
6. 4 44
   Beta 44
   4 44
   Beta 44
   
   

Consider the following array definitions:
int[] array1, array2[];
int[][] array3;
int[] array4[], array5[];
Which of the following are valid statements?

1. array2 = array3;
2. array2 = array4;
3. array1 = array2;
4. array4 = array1;
5. array5 = array3;

What will the following code print?
List s1 = new ArrayList( );
s1.add("a");
s1.add("b");
s1.add("c");
s1.add("a");
System.out.println(s1.remove("a")+" "+s1.remove("x"));

1. 1 0
2. 2 -1
3. 2 0
4. 1 -1
5. true false

What will the following code print?

void crazyLoop(){
  int c = 0;
  JACK: while (c < 8){
    JILL: System.out.println(c);
    if (c > 3) break JACK; else c++;
  }
}

1. It will not compile.
2. It will throw an exception at runtime.
3. It will print numbers from 0 to 8
4. It will print numbers from 0 to 3
5. It will print numbers from 0 to 4

    public static void crazyLoop(){
      int c = 0;
      JACK: while (c < 8){
        JILL: System.out.println("c = "+c);
        for(int k = 0; k<c; k++){
            System.out.println(" k = "+k+" c = "+c);
            if (c > 3) break JACK; 
        }
        c++;
      }
    }

c = 0
c = 1
  k = 0 c = 1
c = 2
  k = 0 c = 2
  k = 1 c = 2
c = 3
  k = 0 c = 3
  k = 1 c = 3
  k = 2 c = 3
c = 4
  k = 0 c = 4

c = 0
c = 1
  k = 0 c = 1
c = 2
  k = 0 c = 2
  k = 1 c = 2
c = 3
  k = 0 c = 3
  k = 1 c = 3
  k = 2 c = 3
c = 4
  k = 0 c = 4
c = 5
  k = 0 c = 5
c = 6
  k = 0 c = 6
c = 7
  k = 0 c = 7

Given:

public class Triangle{
    public int base;
    public int height;
    public double area;
    
    public Triangle(int base, int height){
        this.base = base; this.height = height;
        updateArea();
    }

    void updateArea(){
        area = base*height/2;
    }
    public void setBase(int b){ base  = b; updateArea(); }
    public void setHeight(int h){ height  = h; updateArea(); }
}

1. the base field
2. the height field
3. the area field
4. the Triangle constructor
5. the setBase method
6. the setHeight method