目录
程序清单13_13Rational（在19_12代码中有引用
程序清单19_1GenericStack
package chapter_19;
import java.util.ArrayList;
public class 程序清单19_1GenericStack <E>{
private ArrayList<E> list = new ArrayList<E>();
//private java.util.ArrayList<E> list = new java.util.ArrayList<E>();
public int getSize() {
return list.size();
}
public E peek() {
return list.get(getSize()-1);
}
public void push(E o) {
list.add(o);
}
public E pop() {
E o = list.get(getSize()-1);
list.remove(getSize() - 1);
return o;
}
public boolean isEmpty() {
return list.isEmpty();
}
@Override
public String toString() {
return "stack: " + list.toString();
}
}
程序清单19_2GenericMethodDemo
package chapter_19;
public class 程序清单19_2GenericMethodDemo {
public static void main(String[] args) {
Integer[] integers = {1, 2, 3, 4,5};
String[] strings = {"Lodon","Paris", "New york", "Austin"};
程序清单19_2GenericMethodDemo.<Integer>print(integers);
程序清单19_2GenericMethodDemo.<String>print(strings);
/*print(integers);
print(strings);*/
}
public static <E> void print(E[] list) {
for(int i = 0;i < list.length;i++)
System.out.println(list[i] + " ");
System.out.println();
}
}
输出结果
1 2 3 4 5
Lodon Paris New york Austin 程序清单19_3BoundedTypeDemo
package chapter_19;
public class 程序清单19_3BoundedTypeDemo {
public static void main(String[] args) {
Rectangle rectangle = new Rectangle();
Circle circle = new Circle(2);
System.out.println("Same area? ");
}
public static <E extends GeometriObject> boolean equalArea(
E object1,E object2) {
return object1.getArea() == object2.getArea();
}
}
见程序清单13-4
程序清单19_4GenericSort
package chapter_19;
public class 程序清单19_4GenericSort {
public static void main(String[] args) {
Integer[] intArray = {new Integer(2), new Integer(4),
new Integer(3)};
Double[] doubleArray = {new Double(3.4),new Double(1.3),
new Double(-22.1)};
Character[] charArray = {new Character('a'),
new Character('J'),new Character('r')};
String[] stringArray = {"Tom","Susan","kim"};
sort(intArray);
sort(doubleArray);
sort(charArray);
sort(stringArray);
System.out.print("Sorted Integer objects: ");
printList(intArray);
System.out.print("Sorted Double objects: ");
printList(doubleArray);
System.out.print("Sorted Character objects: ");
printList(charArray);
System.out.print("Sorted String objects: ");
printList(stringArray);
}
public static <E extends Comparable<E>> void sort(E[] list) {
E currentMin;
int currentMinIndex;
for(int i = 0;i < list.length - 1;i++) {
currentMin = list[i];
currentMinIndex = i;
for(int j = i+1;j< list.length;j++) {
if(currentMin.compareTo(list[j])>0){
currentMin = list[j];
currentMinIndex = j;
}
}
if(currentMinIndex != i) {
list[currentMinIndex] = list[i];
list[i] = currentMin;
}
}
}
public static void printList(Object[] list) {
for(int i = 0;i<list.length;i++)
System.out.print(list[i] + " ");
System.out.println();
}
}
程序清单19_5Max
package chapter_19;
public class 程序清单19_5Max {
public static Comparable max(Comparable o1,Comparable o2) {
if(o1.compareTo(o2) > 0)
return o1;
else
return o2;
}
}
程序清单19_6MaxUsingGenericType
package chapter_19;
public class 程序清单19_6MaxUsingGenericType {
public static <E extends Comparable<E>> E max(E o1,E o2) {
if(o1.compareTo(o2)> 0)
return o1;
else
return o2;
}
}
程序清单19_7wildCardNeedDemo
package chapter_19;
public class 程序清单19_7wildCardNeedDemo {
public static void main(String[] args) {
程序清单19_1GenericStack<Integer> intStack = new 程序清单19_1GenericStack<Integer>();
intStack.push(1);
intStack.push(2);
intStack.push(-2);
System.out.println("The max number is "+max(intStack));
}
//public static double max(程序清单19_1GenericStack<Number>stack) {intStack不是GenericStack<Number>的实例，所以这行代码会出错
public static double max(程序清单19_1GenericStack<Integer>stack) {
double max = stack.pop().doubleValue();
while(!stack.isEmpty()) {
double value = stack.pop().doubleValue();
if(value > max)
max = value;
}
return max;
}
}
输出结果
The max number is 2.0
程序清单19_8AnyWildCardDemo
package chapter_19;
public class 程序清单19_8AnyWildCardDemo {
public static void main(String[] args) {
程序清单19_1GenericStack<Integer> intStack = new 程序清单19_1GenericStack<>();
intStack.push(1);
intStack.push(2);
intStack.push(-2);
print(intStack);
}
public static void print(程序清单19_1GenericStack<?> stack) {
while(!stack.isEmpty()) {
System.out.print(stack.pop() + " ");
}
}
}
程序清单19_9SuperWildChardDemo
package chapter_19;
public class 程序清单19_9SuperWildChardDemo {
public static void main(String[] args) {
程序清单19_1GenericStack<String> stack1 = new 程序清单19_1GenericStack<>();
程序清单19_1GenericStack<Object> stack2 = new 程序清单19_1GenericStack<>();
stack2.push("Java");
stack2.push(2);;
stack1.push("Sun");
add(stack1, stack2);
程序清单19_8AnyWildCardDemo.print(stack2);
}
public static <T> void add(程序清单19_1GenericStack<T> stack1,
程序清单19_1GenericStack<? super T> stack2) {
while (!stack1.isEmpty())
stack2.push(stack1.pop());
}
}
输出结果
Sun 2 Java 程序清单19_10GenericMatrix
package chapter_19;
public abstract class 程序清单19_10GenericMatrix <E extends Number>{
protected abstract E add(E o1,E o2);
protected abstract E multiply(E o1,E o2);
protected abstract E zero();
public E[][] addMatrix(E[][] matrix1,E[][] matrix2){
if((matrix1.length != matrix2.length)||
(matrix1[0].length != matrix2[0].length)) {
throw new RuntimeException(
"The matrices do not have the same size");
}
E[][] result =
(E[][])new Number[matrix1.length][matrix1[0].length];
for(int i = 0;i < result[i].length;i++) {
for(int j = 0;j < result[i].length;j++) {
result[i][j] = add(matrix1[i][j],matrix2[i][j]);
}
}
return result;
}
public E[][] multiplyMatrix(E[][] matrix1,E[][] matrix2){
if(matrix1[0].length != matrix2.length) {
throw new RuntimeException(
"The matrices do no have compatible size");
}
E[][] result =
(E[][])new Number[matrix1.length][matrix2[0].length];
for(int i = 0;i < result.length;i++) {
for(int j = 0;j < result[0].length;j++) {
result[i][j] = zero();
for(int k = 0;k < matrix1[0].length;k++) {
result[i][j] = add(result[i][j],
multiply(matrix1[i][k], matrix2[k][j]));
}
}
}
return result;
}
public static void printResult(
Number[][] m1,Number[][] m2,Number[][] m3,char op) {
for(int i = 0;i < m1.length;i++) {
for(int j = 0;j < m1[0].length;j++)
System.out.print(" " + m1[i][j]);
if(i == m1.length/2)
System.out.print(" " + op + " ");
else
System.out.print(" ");
for(int j = 0;j < m2.length;j++)
System.out.print(" " + m2[i][j]);
if(i == m1.length / 2)
System.out.print(" = ");
else
System.out.print(" ");
for(int j = 0;j < m3.length;j++)
System.out.print(m3[i][j] + " ");
System.out.println();
}
}
}
程序清单19_11IntegerMatrix
package chapter_19;
public class 程序清单19_11IntegerMatrix extends 程序清单19_10GenericMatrix<Integer>{
@Override
protected Integer add(Integer o1,Integer o2) {
return o1 + o2;
}
@Override
protected Integer multiply(Integer o1, Integer o2) {
return o1 * o2;
}
@Override
protected Integer zero() {
return 0;
}
}
程序清单19_12RationalMatrix
package chapter_19;
public class 程序清单19_12RationalMatrix extends 程序清单19_10GenericMatrix<程序清单13_13Rational>{
@Override
protected 程序清单13_13Rational add(程序清单13_13Rational r1,程序清单13_13Rational r2) {
return r1.add(r2);
}
@Override
protected 程序清单13_13Rational multiply(程序清单13_13Rational r1,程序清单13_13Rational r2) {
return r1.multiply(r2);
}
@Override
protected 程序清单13_13Rational zero() {
return new 程序清单13_13Rational(0,1);
}
}
程序清单13_13Rational（在19_12代码中有引用
package chapter_19;
public class 程序清单13_13Rational extends Number implements Comparable<程序清单13_13Rational>{
private long numerator = 0;
private long denominator = 1;
public 程序清单13_13Rational() {
this(0,1);
}
public 程序清单13_13Rational(long numerator,long denominator) {
long gcd = gcd(numerator,denominator);
this.numerator = ((denominator > 0)?1:-1)*numerator / gcd;
this.denominator = Math.abs(denominator) / gcd;
}
private static long gcd(long n,long d) {
long n1 =Math.abs(n);
long n2 = Math.abs(d);
int gcd = 1;
for(int k = 1;k <= n1&&k <= n2;k++) {
if(n1 %k == 0&&n2 % k == 0)
gcd = k;
}
return gcd;
}
public long getNumerator() {
return numerator;
}
public long getDenominator() {
return denominator;
}
public 程序清单13_13Rational add(程序清单13_13Rational secondRational) {
long n = numerator * secondRational.getDenominator()+
denominator*secondRational.getNumerator();
long d = denominator * secondRational.getDenominator();
return new 程序清单13_13Rational(n,d);
}
public 程序清单13_13Rational subtract(程序清单13_13Rational secondRational) {
long n = numerator * secondRational.getDenominator()
- denominator * secondRational.getNumerator();
long d = denominator * secondRational.getDenominator();
return new 程序清单13_13Rational(n,d);
}
public 程序清单13_13Rational multiply(程序清单13_13Rational secondRational) {
long n = numerator * secondRational.getNumerator();
long d = denominator * secondRational.getDenominator();
return new 程序清单13_13Rational(n,d);
}
public 程序清单13_13Rational divide(程序清单13_13Rational secondRational) {
long n = numerator * secondRational.getDenominator();
long d = denominator * secondRational.numerator;
return new 程序清单13_13Rational(n,d);
}
@Override
public String toString() {
if(denominator == 1)
return numerator +"";
else
return numerator + "/" + denominator;
}
@Override
public boolean equals(Object other) {
if((this.subtract((程序清单13_13Rational)(other))).getNumerator() == 0)
return true;
else
return false;
}
@Override
public int intValue() {
return (int)doubleValue();
}
@Override
public float floatValue() {
return (float)doubleValue();
}
@Override
public double doubleValue() {
return numerator * 1.0/denominator;
}
@Override
public long longValue() {
return (long)doubleValue();
}
@Override
public int compareTo(程序清单13_13Rational o) {
if(this.subtract(o).getNumerator() > 0)
return 1;
else if(this.subtract(o).getNumerator() < 0)
return -1;
else
return 0;
}
}
程序清单19_13TestIntegerMatrix
package chapter_19;
public class 程序清单19_13TestIntegerMatrix {
public static void main(String[] args) {
Integer[][] m1 = new Integer[][] {{1, 2, 3},{4, 5, 6},{1, 1, 1}};
Integer[][] m2 = new Integer[][] {{1, 1, 1},{2, 2, 2},{0, 0, 0}};
程序清单19_11IntegerMatrix integerMatrix = new 程序清单19_11IntegerMatrix();
System.out.println("\nm1 + m2 is ");
程序清单19_10GenericMatrix.printResult(m1, m2,
integerMatrix.addMatrix(m1, m2), '+');
System.out.println("\nm1 * m2 is ");
程序清单19_10GenericMatrix.printResult(m1, m2,
integerMatrix.multiplyMatrix(m1, m2), '*');
}
}
输出结果
m1 + m2 is
1 2 3 1 1 1 2 3 4
4 5 6 + 2 2 2 = 6 7 8
1 1 1 0 0 0 1 1 1
m1 * m2 is
1 2 3 1 1 1 5 5 5
4 5 6 * 2 2 2 = 14 14 14
1 1 1 0 0 0 3 3 3 程序清单19_14TestRationalMatrix
package chapter_19;
public class 程序清单19_14TestRationalMatrix {
public static void main(String[] args) {
程序清单13_13Rational[][] m1 = new 程序清单13_13Rational[3][3];
程序清单13_13Rational[][] m2 = new 程序清单13_13Rational[3][3];
for(int i = 0;i < m1.length;i++) {
for(int j = 0;j < m1[0].length;j++) {
m1[i][j] = new 程序清单13_13Rational(i+1,j+5);
m2[i][j] = new 程序清单13_13Rational(i+1,j+6);
}
}
程序清单19_12RationalMatrix rationalMatrix = new 程序清单19_12RationalMatrix();
System.out.println("\nm1 + m2 + is ");
程序清单19_10GenericMatrix.printResult(m1, m2,
rationalMatrix.addMatrix(m1, m2), '+');
System.out.println("\nm1 * m2 is ");
程序清单19_10GenericMatrix.printResult(m1, m2,
rationalMatrix.multiplyMatrix(m1, m2), '*');
}
}
输出结果
m1 + m2 + is
1/5 1/6 1/7 1/6 1/7 1/8 11/30 13/42 15/56
2/5 1/3 2/7 + 1/3 2/7 1/4 = 11/15 13/21 15/28
3/5 1/2 3/7 1/2 3/7 3/8 11/10 13/14 45/56
m1 * m2 is
1/5 1/6 1/7 1/6 1/7 1/8 101/630 101/735 101/840
2/5 1/3 2/7 * 1/3 2/7 1/4 = 101/315 202/735 101/420
3/5 1/2 3/7 1/2 3/7 3/8 101/210 101/245 101/280