矩阵的加、减、乘、除、toString、equals、hashCode、clone

package com.jdk7.chapter4;

import java.text.DecimalFormat;
import java.util.Arrays;

/**
 * 数组的加减乘除
 * @author Administrator
 *
 */

public class MatrixData implements Cloneable{
    //声明一个私有double类型的二维数组存放数据,私有变量只能在该类中使用，不能被外部调用
    private double[][] matrixData;
    
    //无参构造函数
    public MatrixData(){
        //用默认值进行初始化
        this.init();
    }
    
    //带参构造函数
    public MatrixData(double[][] b){
        //二维数组b为空则调用默认值进行初始化
        if(!arraySameLength(b)){
            System.out.println("数组第二维长度不等");
            this.init();
        }else{        //二维数组b不为空，则将b克隆
            System.out.println("数组第二维长度都相等");
            this.matrixData = b;
        }
    }
    
    public MatrixData add(MatrixData data){
        if(data==null){return null;}
        
        double[][] datab = data.getMatrixData();
        MatrixData c = null;
        if(!sameLength(data)){
            return c;
        }else{
            double[][] datac = new double[this.matrixData.length][this.matrixData[0].length];
            for(int i=0;i<this.matrixData.length;i++){
                for(int j=0;j<this.matrixData[0].length;j++){
                    datac[i][j] = this.matrixData[i][j] + data.matrixData[i][j];
                }
            }
            c = new MatrixData(datac);
            return c;
        }
    }
    
    public MatrixData sub(MatrixData b){
        if(b==null){return null;}
        double[][] datab = b.getMatrixData();
        MatrixData c = null;
        if(sameLength(b)){
            double[][] datac = new double[this.matrixData.length][this.matrixData[0].length];
            for(int i=0;i<this.matrixData.length;i++){
                for(int j=0;j<this.matrixData[0].length;j++){
                    datac[i][j] = this.matrixData[i][j] - datab[i][j];
                }
            }
            c = new MatrixData(datac);
            return c;
        }else{
            return c;
        }
    }
    
    public MatrixData multiply(MatrixData data){
        if(data==null){return null;}
        double[][] datab = data.getMatrixData();
        MatrixData c = null;
        if(sameLength(data)){
            double[][] datac = new double[this.matrixData.length][this.matrixData[0].length];
            for(int i=0;i<this.matrixData.length;i++){
                for(int j=0;j<this.matrixData[0].length;j++){
                    datac[i][j] = this.matrixData[i][j] * datab[i][j];
                }
            }
            c = new MatrixData(datac);
            return c;
        }else{
            return c;
        }
    }
    
    public MatrixData division(MatrixData data){
        if(data==null){return null;}
        double[][] datax = data.getMatrixData();
        MatrixData c = null;
        if(sameLength(data)){
            double[][] datac = new double[this.matrixData.length][this.matrixData[0].length];
            for(int i=0;i<this.matrixData.length;i++){
                for(int j=0;j<this.matrixData[0].length;j++){
                    if(datax[i][j]==0){
                        System.out.println("商不能为零");
                        break;
                    }else{
                        datac[i][j] = (this.matrixData[i][j] / datax[i][j]);
                    }
                }
            }
            c = new MatrixData(datac);
            return c;
        }else{
            return c;
        }
    }
    
    //判断二维长度是否相等
    public boolean sameLength(MatrixData b){
        if(this.matrixData.length != b.matrixData.length || this.matrixData[0].length != b.matrixData[0].length){
            return false;
        }else{
            return true;
        }
    }

    //默认的二维数组
    private void init() {
        this.matrixData = new double[][]{{1,2,0},{4,5,6},{7,8,9}};
    }
    
    public double[][] getMatrixData() {
        return matrixData;
    }

    public void setMatrixData(double[][] matrixData) {
        this.matrixData = matrixData;
    }

    public Object clone(){
        try {
            System.out.println("调用clone方法");
            MatrixData src = (MatrixData)super.clone();
            src.setMatrixData(this.matrixData);
            return src;
        } catch (CloneNotSupportedException e) {
            e.printStackTrace();
        }
        return null;
    }
    
    public int hashCode(){
        return this.toString().hashCode();
    }
    
    /**
     * 在比较的过程中涉及到多层嵌套条件判断，最外层的正反两面都要给予对应的返回结果，如果内层的返回结果同外层不一致，则需指定确切的返回结果，
     * 反面情况保持默认的返回结果
     */
    public boolean equals(Object data){
        if(data==null){
            return false;
            }
        if(data instanceof MatrixData){
            MatrixData datax = (MatrixData) data;
            if(sameLength(datax)){
                for(int i=0;i<this.matrixData.length;i++){
                    for(int j=0;j<this.matrixData[0].length;j++){
                        if(this.matrixData[i][j] != datax.matrixData[i][j]){
                            return false;
                        }
                    }
                }
            }
        return true;
        }else{return false;}
    }
    //二位数组的二维长度相等
    public boolean arraySameLength(double[][] b){
        for(int i=0;i<b.length-1;i++){
            if(b[i].length != b[i+1].length){
                return false;
            }
        }
        return true;
    }
    
    //将所有的打印信息放入StringBuffer中再转换为String类型，包括空格和换行
    public String arrayToString(double[][] b){
        StringBuffer sb = new StringBuffer("");
        
        //按照指定的格式进行格式化
        DecimalFormat df = new DecimalFormat();
        String pattern = "0.00";
        df.applyPattern(pattern);
        
        for(int i=0;i<b.length;i++){
            for(int j=0;j<b[0].length;j++){
//                sb.append((Double.valueOf(b[i][j])).toString()).append(" ");
                sb.append(df.format((Double.valueOf(b[i][j]))).toString()).append(" ");
            }
            sb.append("
");
        }
        return  sb.toString();
    }
    
    @Override
    public String toString() {
//        return "MatrixData [matrixData=" + Arrays.toString(matrixData) + "]";
        return this.arrayToString(this.matrixData);
    }
    
    public void display(){
        System.out.println(this.toString());
    }

}

package com.jdk7.chapter4;

public class Test {
    public static void main(String[] args) {
        double[][] array0 = new double[][]{{9.0,8.0,7.0},{6.0,5.0,4.0},{3.0,2.0,1.0}};
        MatrixData m0 = new MatrixData(array0);
        MatrixData m1 = new MatrixData();
        System.out.print("数组m0为: ");
        m0.display();
        System.out.print("数组m1为: ");
        m1.display();
        System.out.print("数组(m0 + m1)为: ");
        m0.add(m1).display();
        System.out.print("数组(m0 - m1)为: ");
        m0.sub(m1).display();
        System.out.print("数组(m0 * m1)为: ");
        m0.multiply(m1).display();
        MatrixData m2 = (MatrixData)m0.clone();
        System.out.print("从m0克隆的m2为: ");
        m2.display();
        System.out.println("m0的哈希码为: "+m0.hashCode());
        System.out.println("m2的哈希码为: "+m2.hashCode());
        System.out.println("m0和m2是否相等: "+m0.equals(m2));
        System.out.print("数组m3为: ");
        MatrixData m3 = null;
        UsingArrays ua = new UsingArrays();
        System.out.println("m0和m3是否相等: "+m0.equals(m3));
        System.out.println("m0和m1是否相等: "+m0.equals(m1));
        System.out.println("m0和ua是否相等: "+m0.equals(ua));
        
        System.out.print("数组(m0 / m1)为: ");
        m0.division(m1).display();
    }

}


执行结果：
数组第二维长度都相等
数组m0为: 9.00 8.00 7.00 
6.00 5.00 4.00 
3.00 2.00 1.00 

数组m1为: 1.00 2.00 0.00 
4.00 5.00 6.00 
7.00 8.00 9.00 

数组(m0 + m1)为: 数组第二维长度都相等
10.00 10.00 7.00 
10.00 10.00 10.00 
10.00 10.00 10.00 

数组(m0 - m1)为: 数组第二维长度都相等
8.00 6.00 7.00 
2.00 0.00 -2.00 
-4.00 -6.00 -8.00 

数组(m0 * m1)为: 数组第二维长度都相等
9.00 16.00 0.00 
24.00 25.00 24.00 
21.00 16.00 9.00 

调用clone方法
从m0克隆的m2为: 9.00 8.00 7.00 
6.00 5.00 4.00 
3.00 2.00 1.00 

m0的哈希码为: 363974377
m2的哈希码为: 363974377
m0和m2是否相等: true
数组m3为: m0和m3是否相等: false
m0和m1是否相等: false
m0和ua是否相等: false
数组(m0 / m1)为: 商不能为零
数组第二维长度都相等
9.00 4.00 0.00 
1.50 1.00 0.67 
0.43 0.25 0.11