Java How to Program Fourth Edition - DCC

Chapter 20 Java Utilities Package and Bit Manipulation 1185
Bit 1 Bit 2 Bit 1 ^ Bit 2
0 0 0
1 0 1
0 1 1
1 1 0
Fig. Fig. Fig. 20.10 20.10 Results of combining two bits with the bitwise exclusive OR operator (^).
The bitwise complement operator (~) sets all 1 bits in its operand to 0 in the result and
sets all 0 bits to 1 in the result—otherwise referred to as “taking the one's complement of
the value.” The fourth output window for Fig. 20.8 shows the results of taking the one’s
complement of the value 21845. The result is -21846.
The program of Fig. 20.11 demonstrates the left shift operator () and the right shift operator with zero extension (>>>).
Method getBits (lines 113–138) obtains a String containing the bit representation of
the integer values. The program allows the user to enter an integer into a JTextField
and press Enter to display the bit representation of the integer in a second JTextField.
The the user can press a button representing a shift operation to perform a 1-bit shift and
view the results of the shift in both integer and bitwise representation.
1 // Fig. 20.11: BitShift.java
2 // Using the bitwise shift operators.
3
4 // Java core packages
5 import java.awt.*;
6 import java.awt.event.*;
7
8 // Java extension packages
9 import javax.swing.*;
10
11 public class BitShift extends JFrame {
12 private JTextField bitsField;
13 private JTextField valueField;
14
15 // set up GUI
16 public BitShift()
17 {
18 super( "Shifting bits" );
19
20 Container container = getContentPane();
21 container.setLayout( new FlowLayout() );
22
23 container.add( new JLabel( "Integer to shift " ) );
24
25 // textfield for user to input integer
26 valueField = new JTextField( 12 );
Fig. Fig. 20.11 20.11 Demonstrating the bitwise shift operators (part 1 of 5).