第十九章程序清单合集——Java语言程序设计进阶篇（黑皮书）

目录

程序清单19_1GenericStack

程序清单19_2GenericMethodDemo 

程序清单19_3BoundedTypeDemo 

程序清单19_4GenericSort

程序清单19_5Max

 程序清单19_6MaxUsingGenericType

程序清单19_7wildCardNeedDemo

程序清单19_8AnyWildCardDemo

程序清单19_9SuperWildChardDemo

程序清单19_10GenericMatrix

 程序清单19_11IntegerMatrix

 程序清单19_12RationalMatrix

程序清单13_13Rational（在19_12代码中有引用

程序清单19_13TestIntegerMatrix

程序清单19_14TestRationalMatrix

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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();}@Overridepublic 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;elsereturn 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(" = ");elseSystem.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>{@Overrideprotected Integer add(Integer o1,Integer o2) {return o1 + o2;}@Overrideprotected Integer multiply(Integer o1, Integer o2) {return o1 * o2;}@Overrideprotected 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>{@Overrideprotected 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);}@Overrideprotected 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);}@Overridepublic String toString() {if(denominator == 1)return numerator +"";elsereturn numerator + "/" + denominator;}@Overridepublic boolean equals(Object other) {if((this.subtract((程序清单13_13Rational)(other))).getNumerator() == 0)return true;elsereturn false;}@Overridepublic int intValue() {return (int)doubleValue();}@Overridepublic float floatValue() {return (float)doubleValue();}@Overridepublic double doubleValue() {return numerator * 1.0/denominator;}@Overridepublic long longValue() {return (long)doubleValue();}@Overridepublic 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