关于直接打印一个对象的引用

直接打印一个对象的引用时相当于调用toString()方法

该方法返回一个字符串，其值为： getClass().getName() + '@' + Integer.toHexString(hashCode())

class Date{int year,month,day;Date(int y,int m,int d){year = y;month = m;day = d;}public int compare(Date date){if(year>date.year){return 1;}else if(year<date.year){return -1;}else{if(month>date.month){return 1;}else if(month<date.month){return -1;}else{if(day>date.day){return 1;}else if(day<date.day){return -1;}else{return 0;}}}}public String toString(){//需要重写该方法return "year:month:day--"+year+"--"+month+"--"+day;   }}class dateSortTest{  public static void main(String[] agrs){  Date[] days = new Date[5];  days[0] = new Date(2006,5,4);  days[1] = new Date(2006,7,4);  days[2] = new Date(2008,5,4);  days[3] = new Date(2004,5,9);  days[4] = new Date(2004,5,4);  bubbleSort(days);  for(int i=0;i<days.length;i++){  System.out.println(days[i]);  //直接打印一个对象的引用时相当于调用toString()方法  }  }  public static Date[] bubbleSort(Date[] a){  Date temp;    for(int i=a.length-1;i>0;i--){    for(int j=0;j<i;j++){    if(a[j].compare(a[j+1])>0){    temp = a[j];    a[j] = a[j+1];    a[j+1] = temp;    }    }    }    return a;  }  }