Java泛型——泛型矩阵类

所有矩阵，加法和乘法操作都是类似，所以设计一个父类，不用管元素类型，目的描述所有类型的矩阵共享的通用操作

创建若干适用于指定矩阵类型的子类，实例：两种类型int和Rational的实现

1、GenericMatrix类

public abstract class GenericMatrix <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.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[][] mulyiplyMartix(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][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();
            
        }
    }
 
}

2、IntegerMatrix类

public class IntegerMatrix extends GenericMatrix<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;
    }
    
 
}

3、RationalMatrix类

public class Rational extends Number{
    private long numerator=0;
    private long denominator=1;
    public Rational(){
        this(0,1);
    }
    public Rational(long num1,long num2){
        long gcd=gcd(num1,num2);
        this.numerator=(num2>0?1:-1)*num1/gcd;
        this.denominator=Math.abs(num2)/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 String toString(){
        if(denominator==1)
            return numerator+"";
        else
            return numerator+"/"+denominator;
    }
    @Override
    public double doubleValue() {
        // TODO 自动生成的方法存根
        return numerator*1.0/denominator;
    }
    @Override
    public float floatValue() {
        // TODO 自动生成的方法存根
        return (float) doubleValue();
    }
    @Override
    public int intValue() {
        // TODO 自动生成的方法存根
        return (int) doubleValue();
    }
    @Override
    public long longValue() {
        // TODO 自动生成的方法存根
        return (long) doubleValue();
    }
    public long getNumerator(){
        return numerator;
    }
    public long GetDenominator(){
        return denominator;
    }
    public Rational add(Rational second){
        long n=numerator*second.GetDenominator()+denominator*second.getNumerator();
        long d=denominator*second.GetDenominator();
        return new Rational(n,d);
    }
    public Rational multiply(Rational second){
        long n=numerator*second.getNumerator();
        long d=denominator*second.GetDenominator();
        return new Rational(n,d);
    }
 
}

4、Rational类

public class Rational extends Number{
    private long numerator=0;
    private long denominator=1;
    public Rational(){
        this(0,1);
    }
    public Rational(long num1,long num2){
        long gcd=gcd(num1,num2);
        this.numerator=(num2>0?1:-1)*num1/gcd;
        this.denominator=Math.abs(num2)/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 String toString(){
        if(denominator==1)
            return numerator+"";
        else
            return numerator+"/"+denominator;
    }
    @Override
    public double doubleValue() {
        // TODO 自动生成的方法存根
        return numerator*1.0/denominator;
    }
    @Override
    public float floatValue() {
        // TODO 自动生成的方法存根
        return (float) doubleValue();
    }
    @Override
    public int intValue() {
        // TODO 自动生成的方法存根
        return (int) doubleValue();
    }
    @Override
    public long longValue() {
        // TODO 自动生成的方法存根
        return (long) doubleValue();
    }
    public long getNumerator(){
        return numerator;
    }
    public long GetDenominator(){
        return denominator;
    }
    public Rational add(Rational second){
        long n=numerator*second.GetDenominator()+denominator*second.getNumerator();
        long d=denominator*second.GetDenominator();
        return new Rational(n,d);
    }
    public Rational multiply(Rational second){
        long n=numerator*second.getNumerator();
        long d=denominator*second.GetDenominator();
        return new Rational(n,d);
    }
 
}

5、TestIntegerMatrix 类

public class TestIntegerMatrix {
    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}};
        IntegerMatrix integerMatrix=new IntegerMatrix();
        System.out.println("\nm1+m2 is");
        GenericMatrix.printResult(m1, m2, integerMatrix.addMatrix(m1, m2), '+');
        System.out.println("\nm1*m2 is");
        GenericMatrix.printResult(m1, m2, integerMatrix.mulyiplyMartix(m1, m2), '+');
    }
}

6、TestRationalMatrix 类

public class TestRationalMatrix {
    public static void main(String []args){
    Rational[][] m1=new Rational[3][3];
    Rational[][] m2=new Rational[3][3];
    for(int i=0;i<m1.length;i++)
       for(int j=0;j<m1[0].length;j++){
        m1[i][j]=new Rational(i+1,j+5);
        m2[i][j]=new Rational(i+1,j+6);
        
    }
    RationalMatrix rationalMartrix=new RationalMatrix();
    System.out.println("\nm1+m2 is");
    GenericMatrix.printResult(m1, m2, rationalMartrix.addMatrix(m1, m2), '+');
    
    System.out.println("\nm1*m2 is");
    GenericMatrix.printResult(m1, m2, rationalMartrix.mulyiplyMartix(m1, m2), '*');
    }
}

IntegerMatrix和RationalMatrix是GenericMatrix的具体子类。这两个类实现了在GenericMatrix类中定义的add、multiply和zero方法。矩阵元素的类型Number的泛型子类。这样就可以使用任意Number子类的对象，只要在子类中实现了add、multiply和zero方法就可以使用它们。

原文：https://www.cnblogs.com/Bluebells/p/14290929.html

栏目列表