Computer Questions on Java Programming

int -> 0 String -> “null” Dog -> null char -> ‘\u0000’ float -> 0.0f boolean -> true

int [] myScores []; char [] myChars; int [6] myScores; Dog myDogs []; Dog myDogs [7];

char c1 = 064770; char c2 = ‘face’; char c3 = 0xbeef; char c4 = \u0022; char c5 = ‘\iface’; char c6 = ‘\uface’;

float f1 = -343; float f2 = 3.14; float f3 = 0x12345; float f4 = 42e7; float f5 = 2001.0D; float f6 = 2.81F;

public int a [ ] static int [ ] a public [ ] int a private int a [3] private int [3] a [ ] public final int [ ] a

protected abstract void m1(); static final void m1(){} synchronized public final void m1() {} private native void m1();

private int getArea(); public float getVol(float x); public void main(String [] args); public static void main(String [] args); boolean setFlag(Boolean [] test);

final abstract class Test {} public static interface Test {} final public class Test {} protected abstract class Test {} protected interface Test {} abstract public class Test {}

float[ ] f = new float(3); float f2[ ] = new float[ ]; float[ ]f1 = new float[3]; float f3[ ] = new float[3]; float f5[ ] = {1.0f, 2.0f, 2.0f};

double d = Math.round ( 2.5 + Math.random() );

Math.max(1,4) Math.max(2.3, 5) Math.max(1, 3, 5, 7) Math.max(-1.5, -2.8f)

Thread(Runnable r, String name) Thread() Thread(int priority) Thread(Runnable r, ThreadGroup g) Thread(Runnable r, int priority)

notify(); notifyAll(); isInterrupted(); synchronized(); interrupt(); wait(long msecs); sleep(long msecs); yield();

start() wait() notify() run() terminate()

yield() wait() notify() notifyAll() sleep(1000) aLiveThread.join() Thread.killThread()

wait(2000);

After calling this method, when will the thread A become a candidate to get another turn at the CPU?

run import default implement

The value returned by hashcode() is used in some collection classes to help locate objects. The hashcode() method is required to return a positive int value. The hashcode() method in the String class is the one inherited from Object. Two new empty String objects will produce identical hashcodes

If the equals() method returns true, the hashCode() comparison == must return true. If the equals() method returns false, the hashCode() comparison != must return true. If the hashCode() comparison == returns true, the equals() method must return true. If the hashCode() comparison == returns true, the equals() method might return true.

The Iterator interface declares only three methods: hasNext, next and remove. The ListIterator interface extends both the List and Iterator interfaces. The ListIterator interface provides forward and backward iteration capabilities. The ListIterator interface provides the ability to modify the List during iteration. The ListIterator interface provides the ability to determine its position in the List.

Assertion checking is typically enabled when a program is deployed. It is never appropriate to write code to handle failure of an assert statement. Assertion checking is typically enabled during program development and testing. Assertion checking can be selectively enabled or disabled on a per-package basis, but not on a per-class basis. Assertion checking can be selectively enabled or disabled on both a per-package basis and a per-class basis.

Error Event Object Throwable Exception RuntimeException

Extend java.lang.Thread and override the run() method. Extend java.lang.Runnable and override the start() method. Implement java.lang.Thread and implement the run() method. Implement java.lang.Runnable and implement the run() method. Implement java.lang.Thread and implement the start() method.

Deadlock will not occur if wait()/notify() is used A thread will resume execution as soon as its sleep duration expires. Synchronization can prevent two objects from being accessed by the same thread. The wait() method is overloaded to accept a duration. The notify() method is overloaded to accept a duration. Both wait() and notify() must be called from a synchronized context.

System.out.println(Math.sqrt(-4D));

int i = (int) Math.random();