Explore topic-wise MCQs in Engineering.

What will be the output of the program?

public class Test { private static float[] f = new float[2]; public static void main (String[] args) { System.out.println("f[0] = " + f[0]); } } 

What will be the output of the program?

import java.util.*; class H { public static void main (String[] args) { Object x = new Vector().elements(); System.out.print((x instanceof Enumeration)+","); System.out.print((x instanceof Iterator)+","); System.out.print(x instanceof ListIterator); } }

What will be the output of the program?

TreeSet map = new TreeSet();
map.add("one");
map.add("two");
map.add("three");
map.add("four");
map.add("one");
Iterator it = map.iterator();
while (it.hasNext() ) { System.out.print( it.next() + " " );
}

What will be the output of the program?

public static void main(String[] args) { Object obj = new Object() { public int hashCode() { return 42; } }; System.out.println(obj.hashCode()); }

What will be the output of the program?

int I = 0;
label: if (I < 2) { System.out.print("I is " + I); I++; continue label;
}

What will be the output of the program?

int i = l, j = -1; switch (i) { case 0, 1: j = 1; /* Line 4 */ case 2: j = 2; default: j = 0; } System.out.println("j = " + j); 

What will be the output of the program?

public class SwitchTest { public static void main(String[] args) { System.out.println("value =" + switchIt(4)); } public static int switchIt(int x) { int j = 1; switch (x) { case l: j++; case 2: j++; case 3: j++; case 4: j++; case 5: j++; default: j++; } return j + x; } }

What will be the output of the program?

public class If2 { static boolean b1, b2; public static void main(String [] args) { int x = 0; if ( !b1 ) /* Line 7 */ { if ( !b2 ) /* Line 9 */ { b1 = true; x++; if ( 5 > 6 ) { x++; } if ( !b1 ) x = x + 10; else if ( b2 = true ) /* Line 19 */ x = x + 100; else if ( b1 | b2 ) /* Line 21 */ x = x + 1000; } } System.out.println(x); }
}

What will be the output of the program?

public class Test { private static int[] x; public static void main(String[] args) { System.out.println(x[0]); } }

What will be the output of the program?

import java.util.*; class I { public static void main (String[] args) { Object i = new ArrayList().iterator(); System.out.print((i instanceof List)+","); System.out.print((i instanceof Iterator)+","); System.out.print(i instanceof ListIterator); } }

What will be the output of the program?

package foo; import java.util.Vector; /* Line 2 */
private class MyVector extends Vector { int i = 1; /* Line 5 */ public MyVector() { i = 2; } } public class MyNewVector extends MyVector { public MyNewVector () { i = 4; /* Line 15 */ } public static void main (String args []) { MyVector v = new MyNewVector(); /* Line 19 */ } }

What will be the output of the program?

public class Test { public static void main (String[] args) { String foo = args[1]; String bar = args[2]; String baz = args[3]; System.out.println("baz = " + baz); /* Line 8 */ } }

And the command line invocation:

> java Test red green blue

What will be the output of the program?

public class Test { public static void main (String args[]) { String str = NULL; System.out.println(str); } }

What will be the output of the program?

public class Switch2 { final static short x = 2; public static int y = 0; public static void main(String [] args) { for (int z=0; z < 3; z++) { switch (z) { case x: System.out.print("0 "); case x-1: System.out.print("1 "); case x-2: System.out.print("2 "); } } }
}

What will be the output of the program?

int i = 1, j = 10; do { if(i > j) { break; } j--; } while (++i < 5); System.out.println("i = " + i + " and j = " + j);

Which two are valid constructors for Thread?

1. Thread(Runnable r, String name)
2. Thread()
3. Thread(int priority)
4. Thread(Runnable r, ThreadGroup g)
5. Thread(Runnable r, int priority)

class X implements Runnable { public static void main(String args[]) { /* Missing code? */ } public void run() {} }

Which three are methods of the Object class?

1. notify();
2. notifyAll();
3. isInterrupted();
4. synchronized();
5. interrupt();
6. wait(long msecs);
7. sleep(long msecs);
8. yield();

switch(x) { default: System.out.println("Hello"); }

1. byte
2. long
3. char
4. float
5. Short
6. Long

public void test(int x) { int odd = 1; if(odd) /* Line 4 */ { System.out.println("odd"); } else { System.out.println("even"); } }

public class While { public void loop() { int x= 0; while ( 1 ) /* Line 6 */ { System.out.print("x plus one is " + (x + 1)); /* Line 8 */ } }
}

Which three guarantee that a thread will leave the running state?

1. yield()
2. wait()
3. notify()
4. notifyAll()
5. sleep(1000)
6. aLiveThread.join()
7. Thread.killThread()

Which two of the following methods are defined in class Thread?

1. start()
2. wait()
3. notify()
4. run()
5. terminate()

Which method must be defined by a class implementing the java.lang.Runnable interface?

Which of the following will directly stop the execution of a Thread?

Which will contain the body of the thread?

Which method registers a thread in a thread scheduler?

Which of the following will not directly cause a thread to stop?

Which class or interface defines the wait(), notify(),and notifyAll() methods?

public class MyRunnable implements Runnable { public void run() { // some code here }
}

public class Test { public void foo() { assert false; /* Line 5 */ assert false; /* Line 6 */ } public void bar() { while(true) { assert false; /* Line 12 */ } assert false; /* Line 14 */ } }

What will be the output of the program?

public class Test { public static int y; public static void foo(int x) { System.out.print("foo "); y = x; } public static int bar(int z) { System.out.print("bar "); return y = z; } public static void main(String [] args ) { int t = 0; assert t > 0 : bar(7); assert t > 1 : foo(8); /* Line 18 */ System.out.println("done "); }
}

What will be the output of the program (when you run with the -ea option) ?

public class Test { public static void main(String[] args) { int x = 0; assert (x > 0) : "assertion failed"; /* Line 6 */ System.out.println("finished"); } }

Which two cause a compiler error?

1. float[ ] f = new float(3);
2. float f2[ ] = new float[ ];
3. float[ ]f1 = new float[3];
4. float f3[ ] = new float[3];
5. float f5[ ] = {1.0f, 2.0f, 2.0f};

Given a method in a protected class, what access modifier do you use to restrict access to that method to only the other members of the same class?

public class Test2 { public static int x; public static int foo(int y) { return y * 2; } public static void main(String [] args) { int z = 5; assert z > 0; /* Line 11 */ assert z > 2: foo(z); /* Line 12 */ if ( z < 7 ) assert z > 4; /* Line 14 */ switch (z) { case 4: System.out.println("4 "); case 5: System.out.println("5 "); default: assert z < 10; } if ( z < 10 ) assert z > 4: z++; /* Line 22 */ System.out.println(z); }
}

Which is a valid declaration within an interface?

What is the widest valid returnType for methodA in line 3?

public class ReturnIt { returnType methodA(byte x, double y) /* Line 3 */ { return (long)x / y * 2; } }

class A { protected int method1(int a, int b) { return 0; } }

Which one creates an instance of an array?

What is the most restrictive access modifier that will allow members of one class to have access to members of another class in the same package?

Which two of the following are legal declarations for nonnested classes and interfaces?

1. final abstract class Test {}
2. public static interface Test {}
3. final public class Test {}
4. protected abstract class Test {}
5. protected interface Test {}
6. abstract public class Test {}

Which of the following class level (nonlocal) variable declarations will not compile?

Which of the following is/are legal method declarations?

1. protected abstract void m1();
2. static final void m1(){}
3. synchronized public final void m1() {}
4. private native void m1();

Which cause a compiler error?

What will be the output of the program?

class A { final public int GetResult(int a, int b) { return 0; } } class B extends A { public int GetResult(int a, int b) {return 1; } } public class Test { public static void main(String args[]) { B b = new B(); System.out.println("x = " + b.GetResult(0, 1)); } }

What will be the output of the program?

public class A
{ void A() /* Line 3 */ { System.out.println("Class A"); } public static void main(String[] args) { new A(); } }

What will be the output of the program?

class Super
{ public int i = 0; public Super(String text) /* Line 4 */ { i = 1; } } class Sub extends Super
{ public Sub(String text) { i = 2; } public static void main(String args[]) { Sub sub = new Sub("Hello"); System.out.println(sub.i); } }

What will be the output of the program?

public class Test { public int aMethod() { static int i = 0; i++; return i; } public static void main(String args[]) { Test test = new Test(); test.aMethod(); int j = test.aMethod(); System.out.println(j); }
}

Which statement is true for the class java.util.HashSet?