啊 关于数组的调用有关问题

高手指点啊 关于数组的调用问题
import java.io.*;
class lianlian
{ 
 int i=0;
 int num[]; 
 public void set(int count)
  {
String str;  
  BufferedReader buf=new BufferedReader(new InputStreamReader(System.in));
  for( i=0;i<=count-1;i++)
  {
  System.out.print("请输入第"+(i+1)+"个学生的成绩：");
   
try {
str=buf.readLine();
num[i]=Float.parseFloat(str); 
} 
catch (NumberFormatException e) {
// TODO 自动生成 catch 块
e.printStackTrace();
}
catch (IOException e) {
// TODO 自动生成 catch 块
e.printStackTrace();
}finally {}
  }

  }
public void shuchu(int count){

  for( i=0;i<= count-1;i++)
  {
System.out.println(+num[i]);
  }
} 
class mm
{
  public static void main(String[] args) throws IOException
{
lianlian num = new lianlian();
num.set(4);
  num.shuchu(4);
}
}



怎么调试不过啊 高手指点啊

------解决方案--------------------
package test;

import java.io.*;

class lianlian {
int i = 0;
int[] num = new int[10];

public void set(int count) {
String str;
BufferedReader buf = new BufferedReader(
new InputStreamReader(System.in));
for (i = 0; i <= count - 1; i++) {
System.out.print("请输入第" + (i + 1) + "个学生的成绩：");
try {
str = buf.readLine();
num[i] = Integer.parseInt(str);
} catch (NumberFormatException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
}

}

public void shuchu(int count) {
for (i = 0; i <= count - 1; i++) {
System.out.println(i + "的成绩为：" + num[i]);
}
}
}

public class MM {
public static void main(String[] args) {
lianlian num = new lianlian();
num.set(4);
num.shuchu(4);
}
}
------解决方案--------------------
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
class lianlian 
{
  
private static double num[]=new double[100];
public static void set(int count) 
{ 
String str;
BufferedReader buf=new BufferedReader(new InputStreamReader(System.in));
for(int i=0;i <=count-1;i++) 
{ 
System.out.print("请输入第"+(i+1)+"个学生的成绩："); 

try { 
str=buf.readLine(); 
num[i]=java.lang.Double.parseDouble(str);
}
catch (NumberFormatException e) 
{ 
e.printStackTrace(); 
} 
catch (IOException e)
{ 
e.printStackTrace(); 
}finally
{
}
}
}
 
public void shuchu(int count){ 

for(int i=0;i<count;i++) 
{ 
System.out.println(+num[i]); 
} 
}
}
class mm 
{ 
public static void main(String[] args)
{ 
lianlian num = new lianlian(); 
num.set(4); 
num.shuchu(4); 
} 
}