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Commit 6cc2f10

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ChrisMayfieldChrisMayfield
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ch09 revisions
1 parent 4ce6193 commit 6cc2f10
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‎ch09/ArgValid.java‎

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+20Lines changed: 20 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,20 @@
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/**
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* Example of argument validation.
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*/
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public class ArgValid {
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public static boolean isCapitalized(String str) {
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if (str == null || str.isEmpty()) {
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return false;
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}
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return Character.isUpperCase(str.charAt(0));
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}
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public static void main(String[] args) {
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System.out.println(isCapitalized("Hi!"));
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System.out.println(isCapitalized("bye"));
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System.out.println(isCapitalized(""));
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System.out.println(isCapitalized(null));
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}
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}
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‎ch09/BigInt.java‎

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+20Lines changed: 20 additions & 0 deletions
Original file line numberDiff line numberDiff line change
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import java.math.BigInteger;
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/**
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* BigInteger examples.
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*/
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public class BigInt {
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public static void main(String[] args) {
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long x = 17;
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BigInteger big = BigInteger.valueOf(x);
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String s = "12345678901234567890";
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BigInteger bigger = new BigInteger(s);
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BigInteger a = BigInteger.valueOf(17);
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BigInteger b = BigInteger.valueOf(1700000000);
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BigInteger c = a.add(b);
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}
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}
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‎ch09/Objects.java‎

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+20-16Lines changed: 20 additions & 16 deletions
Original file line numberDiff line numberDiff line change
@@ -1,5 +1,3 @@
1-
import java.math.BigInteger;
2-
31
/**
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* Demonstrates uses of objects and wrappers.
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*/
@@ -14,22 +12,40 @@ public static void main(String[] args) {
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char[] array = {'c', 'a', 't'};
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String word = "dog";
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String word1 = new String("dog"); // creates a string object
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String word2 = "dog"; // implicitly creates a string object
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// the null keyword
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String name0 = null;
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int[] combo = null;
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// System.out.println(name0.length()); // NullPointerException
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// System.out.println(combo[0]); // NullPointerException
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// Strings are immutable
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String name = "Alan Turing";
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String upperName = name.toUpperCase();
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name.toUpperCase(); // ignores the return value
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System.out.println(name);
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name = name.toUpperCase(); // references the new string
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System.out.println(name);
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String text = "Computer Science is fun!";
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text = text.replace("Computer Science", "CS");
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// Wrapper classes
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Integer i = Integer.valueOf(5);
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System.out.println(i.equals(5)); // displays true
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Integer x = Integer.valueOf(123);
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Integer y = Integer.valueOf(123);
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if (x == y) { // false
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if (x == y) { // false
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System.out.println("x and y are the same object");
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}
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if (x.equals(y)) { // true
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if (x.equals(y)) { // true
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System.out.println("x and y have the same value");
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}
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@@ -38,18 +54,6 @@ public static void main(String[] args) {
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num = 12345;
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str = Integer.toString(num);
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// BigInteger arithmetic
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long z = 17;
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BigInteger big = BigInteger.valueOf(z);
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String s = "12345678901234567890";
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BigInteger bigger = new BigInteger(s);
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BigInteger a = BigInteger.valueOf(17);
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BigInteger b = BigInteger.valueOf(1700000000);
52-
BigInteger c = a.add(b);
5357
}
5458

5559
}
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‎ch09/Tables.java‎

Copy file name to clipboardExpand all lines: ch09/Tables.java
+13-25Lines changed: 13 additions & 25 deletions
Original file line numberDiff line numberDiff line change
@@ -4,73 +4,61 @@
44
public class Tables {
55

66
public static void printRow() {
7-
int i = 1;
8-
while (i <= 6) {
7+
for (int i = 1; i <= 6; i++) {
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System.out.printf("%4d", 2 * i);
10-
i = i + 1;
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}
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System.out.println();
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}
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public static void printRow(int n) {
16-
int i = 1;
17-
while (i <= 6) {
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for (int i = 1; i <= 6; i++) {
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System.out.printf("%4d", n * i); // generalized n
19-
i = i + 1;
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}
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System.out.println();
2218
}
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public static void printTable() {
25-
int i = 1;
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while (i <= 6) {
21+
for (int i = 1; i <= 6; i++) {
2722
printRow(i);
28-
i = i + 1;
2923
}
3024
}
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3226
public static void printTable(int rows) {
33-
int i = 1;
34-
while (i <= rows) { // generalized rows
27+
for (int i = 1; i <= rows; i++) { // generalized rows
3528
printRow(i);
36-
i = i + 1;
3729
}
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}
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4032
public static void printRow(int n, int cols) {
41-
int i = 1;
42-
while (i <= cols) { // generalized cols
33+
for (int i = 1; i <= cols; i++) { // generalized cols
4334
System.out.printf("%4d", n * i);
44-
i = i + 1;
4535
}
4636
System.out.println();
4737
}
4838

4939
public static void printTable2(int rows) {
50-
int i = 1;
51-
while (i <= rows) {
52-
printRow(i, rows); // added rows argument
53-
i = i + 1;
40+
for (int i = 1; i <= rows; i++) {
41+
printRow(i, rows);
5442
}
5543
}
5644

5745
public static void main(String[] args) {
58-
System.out.println("printRow()");
46+
System.out.println("\nprintRow()");
5947
printRow();
6048

61-
System.out.println("printRow(6)");
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System.out.println("\nprintRow(6)");
6250
printRow(6);
6351

64-
System.out.println("printTable()");
52+
System.out.println("\nprintTable()");
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printTable();
6654

67-
System.out.println("printTable(6)");
55+
System.out.println("\nprintTable(6)");
6856
printTable(6);
6957

70-
System.out.println("printRow(6, 6)");
58+
System.out.println("\nprintRow(6, 6)");
7159
printRow(6, 6);
7260

73-
System.out.println("printTable2(6)");
61+
System.out.println("\nprintTable2(6)");
7462
printTable2(6);
7563
}
7664

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