数组中的各项问题（数组初始定义及两个应用实例）

矫情吗；* 2022-06-01 11:13 93阅读 0赞

package c;  
/\*java是面向对象的编程语言，所以JAVA语言中的数组也略有不同数组元素可以是想要的对象；\*/  
class D\_Card\{  
long card\_num;  
double balance;  
D\_Card(long n,double b)\{  
card\_num=n;  
balance=b;  
\}  
\}  
public class array \{  
public static void main(String args\[\])  
\{  
int x\[\];  
D\_Card dc\[\];  
x=new int\[3\];  
dc=new D\_Card\[2\];  
System.out.println("x="+x+"dc="+dc);  
System.out.println(x\[0\]);  
System.out.println(dc\[0\]);  
\}  
\}  
//当数组元素为参考类型时，若未赋值，默认为null  
/\*x=\[I@15db9742dc=\[Lc.D\_Card;@6d06d69c  
0

null\*/

/\*数组的三种初始方式\*/

（1）声明和创建数组对象的合写

int x\[\]=new int\[3\];

D\_Card dc=new D\_Card\[2\];

(2)声明和创建数组对象和赋值的合写

int x\[\]=\{20,30,40\};

D\_Card dc\[\]=\{new D\_Card(2323,2,3),new Card(323,4,5)\};

int x\[\]=new int\{2,3,4\};

D\_Card dc\[\]=new D\_Card\{new D\_Card\{3,43,3\},new D\_Card\{1,2,3\}\};

//计算二位数组的行数、列数  
class array\{  
public static void main(String args\[\])\{  
int y\[\]\[\]=new int\[2\]\[3\];  
System.out.println("y="+y);  
System.out.println("y.length "+y.length);  
System.out.println("y\[0\].length "+y\[0\].length);  
\}  
\}/\*y=\[\[I@15db9742  
y.length 2  
y\[0\].length 3 \*/

数组操作实例：

package c;  
import java.io.\*;  
class arr\{  
int a\[\];  
arr(int n)\{  
int a\[\]=new int\[n\];  
\}  
int getmax()\{  
int max=a\[0\];  
for(int i=0;i<a.length;i++)  
\{  
if (a\[i\]>max)  
max=a\[i\];  
\}  
return max;  
\}  
int getmin()\{  
int min=a\[0\];  
for(int i=0;i<a.length;i++)\{  
if(a\[i\]<min)  
a\[i\]=min;  
\}  
return min;  
\}  
int getsum()\{  
int sum=0;  
for(int i=0;i<a.length;i++)\{  
sum=sum+a\[i\];  
\}  
return sum;  
\}  
int getaverage()\{  
int aver=getsum()/a.length;  
return aver;  
\}  
\}  
public class ArrayOperator \{  
public static void main(String args\[\])\{  
String s=null;int n=0;arr ab=null;  
try\{  
System.out.println("输入数组元素个数： ");  
BufferedReader br=new BufferedReader(new InputStreamReader(System.in));  
s=br.readLine();  
n=Integer.parseInt(s);  
ab=new arr(n);  
for(int i=0;i<ab.a.length;i++)\{  
System.out.println("输入a\["+i+"\]:");  
s=br.readLine();ab.a\[i\]=Integer.parseInt(s);  
\}  
\}catch(IOException e)\{System.out.println(e.toString());\}  
System.out.println("max="+ab.getmax());  
System.out.println("min="+ab.getmin());  
System.out.println("getaverage="+ab.getaverage());  
System.out.println("sum="+ab.getsum());  
\}\}  
  
输入学生信息，然后排序并获得相应学生信息：

package c;  
import java.io.\*;  
//学生信息输入  
class pst\{  
Student2 st\[\]=new Student2\[30\];  
void mkst()\{  
String sn=null,nm=null,ss=null,as=null;  
int a=0;  
try\{  
BufferedReader br=new BufferedReader(new InputStreamReader(System.in));  
for(int i=0;i<st.length;i++)  
\{  
System.out.println("studentNo:");  
sn=br.readLine();  
System.out.println("StudentName:");  
nm=br.readLine();  
System.out.println("StudentSex:");  
ss=br.readLine();  
System.out.println("studentAge:");  
as=br.readLine();a=Integer.parseInt(as);  
st\[i\]=new Student2(sn,nm,ss,a);  
\}  
\}catch(IOException e)\{System.out.println(e.toString());\}  
\}  
void sortp()\{  
int i,j;  
Student2 t=null;  
for(i=0;i<st.length;i++)\{  
for(j=i;j<st.length;j++)\{  
if(st\[i\].age>st\[j\].age)  
\{  
t=st\[i\];  
st\[i\]=st\[j\];  
st\[j\]=t;  
\}  
\}  
\}  
for(i=0;i<st.length;i++)  
System.out.println(st\[i\].toString());  
\}  
void searchp(String sn)\{  
int i=0;  
for(i=0;i<st.length;i++)\{  
if(st\[i\].studentNo.equals(sn))\{  
st\[i\].updateage(st\[i\].getage()+1);  
System.out.println(st\[i\].toString());  
break;  
\}  
\}  
\}  
\}  
class Student2\{  
String studentNo,name,sex;  
int age;  
String getstudentNo()\{  
return studentNo;  
\}  
String getname()\{  
return name;  
\}  
String getsex()\{  
return sex;  
\}  
int getage()\{  
return age;  
\}  
void updateage(int a)\{  
age=a;  
\}  
Student2(String sn,String nm,String psex,int a)\{  
studentNo=sn;  
name=nm;  
sex=psex;  
age=a;  
\}  
public String toString()\{  
return(studentNo+";"+name+";"+sex+";"+age+";");  
\}  
\}  
public class ArrayOperator1\{  
public static void main(String args\[\])\{  
int i;  
String sn;  
pst pst1=new pst();  
pst1.mkst();  
pst1.sortp();  
try\{  
BufferedReader br=new BufferedReader(new InputStreamReader(System.in));  
System.out.println("studentNo:");  
sn=br.readLine();  
pst1.searchp(sn);  
\}catch(IOException e)\{System.out.println(e.toString());\}  
\}  
\}