problem

5. Given:
public class Foo {
    public static void main (String [] args)  {
        StringBuffer a = new StringBuffer("A");
        StringBuffer b = new StringBuffer ("B");
        operate (a,b);
        System.out.println(a + "," +b);
    }
    static void operate(StringBuffer x, StringBuffer y) {
        x.append(y);
        y = x;
    }
}

===================== http://www.opcol.com/

6. Given:
public class Test {
    public static void stringReplace (String text) {
        text = text.replace('j', 'i');
    }
    public static void bufferReplace (StringBuffer text) {
        text = text.append ('c');
    }
    public static void main (String args[]) {
        String textString = new String ("java");
        StringBuffer textBuffer = new StringBuffer("java");
        stringReplace(textString);
        bufferReplace(textBuffer);
        System.out.println (textString + textBuffer);
    }
}

=======================
public class Test {
    public static void add3(Integer i) {
        int val = i.intValue();
        val += 3;
        i = new Integer(val);
    }
    public static void main(String args[]){
        Integer  i = new Integer(0);
        add3 (i);
    System.out.println (i.intValue());
    }
}
====================
18. Which three are valid declarations of a float? (Choose Three)
A. float foo = -1;
B. float foo = 1.0;
C. float foo = 42e1;
D. float foo = 2.02f;
E. float foo = 3.03d;
F. float foo = 0x0123;
========================
15. Given:
interface Foo {
    int k = 0;          //line 2
}
public class Test implements Foo {
    public static void main(String args[]) {
        int i;
        Test test = new Test();
        i = test.k;     //8
        i = Test.k;     //9
        i = Foo.k;      //10
    }
}
============================
22. Given:
public class Foo {
    public static void main (String[] args) {
        String s;
        System.out.println (“s=” + s);
    }
}
=============================
26. Given:
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.printIn(j);
    }
}
What is the result?
A. Compilation will fail.
B. Compilation will succeed and the program will print “0”.
C. Compilation will succeed and the program will print “1”.
D. Compilation will succeed and the program will print “2”.

==========================
27. Given:
class Super {
    public float getNum() {return 3.0f;}
}
public class Sub extends Super {
    //line 5
)
Which method, placed at line 5, will cause a compiler error?
A. public float getNum() { return 4.0f; }
B. public void getNum() {}
C. public void getNum(double d) {}
D. public double getNum(float d) {retrun 4.0f; }
==========================
29. Given:
byte [] array1, array2[];
byte array3 [][];
byte[][] array4;
If each array has been initialized, which statement will cause a compiler error?
A. array2 = array1;
B. array2 = array3;
C. array2 = array4;
D. both A and B
E. both A and C
F. both B and C
=========================
52. Given:
public class Test {
    public static String output = "";
    public static void foo(int i) {
        try {
            if(i==1) {
                throw new Exception ();
            }
            output += "1";
        } catch(Exception e) {
            output += “2”;
            return;
        } finally (
            output += “3”;
        }
        output += “4”;
    }
    public static void main (String args[])  (
        foo(0);
        foo(1);
        //line 24
    }
)
=========================
53. Given:
public class Foo implements Runnable {      //line 1
    public void run (Thread t) {            //line 2
        System.out.println("Running.");
    }
    public static void main (String[] args) {
        new Thread(new Foo()).start();
    }
}
========================
59. Given:
public class X implements Runnable {
    private int x;
    private int y;
    public static void main(String[] args) {
        X that = new X();
        (new Thread(that)).start();         //line 7
        (new Thread(that)).start();         //line 8
    }
    public synchronized void run{} {        //line 11
        for (;;) {
            x++;
            y++;
            System.out.println(“x = “ +  x  + “, y = “ + y);
        }
    }  
}
===============================
61. Given:
public class SyncTest{
    public static void main(String[] args)  {
        final StringBuffer s1= new StringBuffer();
        final StringBuffer s2= new StringBuffer();
        new Thread () {
            public void run() {
                synchronized(s1) {
                    s2.append(“A”);
                    synchronized(s2) {
                        s2.append(“B”);
                        System.out.print(s1);
                        System.out.print(s2);
                        }
                }
            }
        }.start();
        new Thread() {
            public void run() {
                synchronized(s2) {
                    s2.append(“C”);
                    synchronized(s1)
                        s1.append(“D”);
                        System.out.print(s2);
                        System.out.print(s1);
                    }
                }
            }
        }.start();
    }
}
Which two statements are true? (Choose Two)
A. The program prints “ABBCAD”
B. The program prints “CDDACB”
C. The program prints “ADCBADBC”
D. The output is a non-deterministic point because of a
possible deadlock condition
E. The output is dependent on the threading model of the
system the program is running on.
============================
68. Given:
class A {
    public int getNumber(int a) {
        return a + 1;
    }
}
class B extends A {
    public int getNumber(int a) {
        return a + 2;           //line 8
    }
    public static void main (String args[])  {
        A a = new B();          //line 13
        System.out.println(a.getNumber(0));     //line 14
    }
}
What is the result?
A. Compilation succeeds and 1 is printed.
B. Compilation succeeds and 2 is printed.
C. An error at line 8 causes compilation to fail.
D. An error at line 13 causes compilation to fail.
E. An error at line 14 causes compilation to fail.
Answer: B
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