Reference no: EM13761697
- How does a variable of a primitive type differ from a reference variable?
- What does the operator new do
- Consider the following statements:
String str = "Going to the amusement park"
char ch;
int len;
int position;
a. What value is stored in ch by the following statement? ch = str.charAt(0);
b. What value is stored in ch by the following statement? ch = str.charAt(10);
c. What value is stored in len by the following statement? len = str.length();
d. What value is stored in position by the following statement? position = str.indexOf('t');
e. What value is stored in position by the following statement? position = str.indexOf("park");
- Which of the following statements are valid? If they are invalid, explain why.
b. System.out.println(cube(num1, num3, num2));
c. System.out.println(cube(6.0, 8.0, 10.5));
d. System.out.println(num1 + " " + num3);
e. System.out.println(cube(num1, num3));
f. value = cube(num1, int2, num3);
g. value = cube(7, 8, 9);
- Why do users prefer a GUI over a nongraphical user interface?
- Write necessary statements to create the following GUI components:
a. A JLabel with the text string "Enter the number of courses"
b. A JButton with the text string "Run"
c. The title "Welcome Home!" for an existing window
d. A width of 200 pixels and a height of 400 pixels for an existing window
- Correct the syntax errors in the following program:
public class RTwo extends JFrame
{
public RTwoProgram()
{
private JLabel length, width, area;
setTitle("Good day Area");
length = JLabel("Enter the length);
width = JLabel("Enter the width);
area = JLabel("Area: ");
containerPane = ContentPane();
pane.setLayout(GridLayout(4,1));
setSize(WIDTH,HEIGHT);
setVisible();
setDefaultCloseOperation(EXIT_ON_CLOSE);
}
public static void main(String args[])
{
RTwoProgram R2 = new RTwoProgram();
}
}
9. What is the output of the following program segments?
a. if (6<2*5)
System.out.print("Hello");
System.out.print(" There");
b. if ('a' > 'b' || 66 > (int)('A'))
System.out.println("#*#");
c. if (7<=7)
System.out.println(6 - 9 * 2 / 6);
d. if { (7<8)
System.out.println("2 4 6 8");
System.out.println("1 3 5 7); }
e. if (5 < 3)
System.out.println("*");
else if
(7 == 8) System.out.println("&");
else
System.out.println("tiny_mce_markerquot;);
- . Write Java statements that output Democrat if the party affiliation code is 'D', Republican if the party affiliation code is 'R', and other otherwise.
- Suppose that you have the following declaration:
int j = 0;
The output of the statement
if ((8 > 4) || (j++ == 7)) System.out.println("j = " + j);
is
j=0
while the output of the statement
if ((8 > 4) | (j++ == 7)) System.out.println("j = " + j);
is
j = 1
Explain why.
- Suppose the input is 5. What is the value of alpha after the following Java code executes? (Assume that alpha is an int variable and console is a Scanner object initialized to the keyboard.)
alpha = console.nextInt();
switch (alpha)
{
case 1:
case 2:
alpha = alpha + 2;
break;
case 4:
alpha++;
case 5:
alpha = 2 * alpha;
case 6: alpha = alpha + 5; break;
default:
alpha--;
}
- Suppose the input is 6. What is the value of a after the following Java code executes? (Assume that all variables are properly declared.)
a = console.nextInt();
if (a > 0)
switch (a)
{
case 1:
a = a + 3;
case 3:
a++;
break;
case 6:
a = a + 6;
case 8: a
= a * 8;
break;
default:
a--;
}
else
a = a + 2;
- The following program contains errors. Correct them so that the program runs and outputs w =21.
public class Mystery
{
static final int SECRET = 5;
public static void main(String[] args)
{
int x, y, w, z;
z = 9;
if z > 10
x = 12; y = 5, w = x + y + SECRET;
else
x = 12; y = 4, w = x + y + SECRET;
System.out.println("w = " + w);
}
}
- Name two GUI input components.