我想是先创建1个文件,然后写入这些东西,为什么最后是 NullPointerException异常呢?
import java.io.*;
import java.util.ArrayList;
public interface wo1{
int c=0;
void set(String a,String b);
}
class wo10 implements wo1{
int c;
String a;
String b;
public void set(String a,String b)
{this.a=a;
this.b=b;
}
public String toString()
{String infor="物品:"+a+" "+"出处:"+b+" "+"级别:"+c;
return infor;}
public String geta()
{return a;}
public String getb()
{return b;}
public int getc()
{return c;}
}
class wo7{
public static void main(String[] args)throws Exception{
File as=new File("c:\\qw.txt");
try{
as.createNewFile();
}
catch(Exception e){}
File[] sa=as.listFiles();
for(int i=0;i<sa.length;i++)
{System.out.println(sa[i]);}
wo10 ee=new wo10();
wo10 ee1=new wo10();
ee.set("图纸","世界");
ee1.set("阿曼尼壁垒","祖阿曼");
ArrayList arr=new ArrayList();
arr.add(ee);
arr.add(ee1);
System.out.println("掉落"+arr.size()+"件");
for(int i=0;i<arr.size();i++)
{System.out.println(arr.get(i));}
arr.remove(ee);
for(int i=0;i<arr.size();i++)
{System.out.println(arr.get(i));}
File f=new File("d:\\dsa.txt");
FileOutputStream out=new FileOutputStream(f);
try{
out.write(ee1.toString().trim().getBytes());
out.close();
}
catch(Exception e){}
}
}
import java.io.*;
import java.util.ArrayList;
public interface wo1{
int c=0;
void set(String a,String b);
}
class wo10 implements wo1{
int c;
String a;
String b;
public void set(String a,String b)
{this.a=a;
this.b=b;
}
public String toString()
{String infor="物品:"+a+" "+"出处:"+b+" "+"级别:"+c;
return infor;}
public String geta()
{return a;}
public String getb()
{return b;}
public int getc()
{return c;}
}
class wo7{
public static void main(String[] args)throws Exception{
File as=new File("c:\\qw.txt");
try{
as.createNewFile();
}
catch(Exception e){}
File[] sa=as.listFiles();
for(int i=0;i<sa.length;i++)
{System.out.println(sa[i]);}
wo10 ee=new wo10();
wo10 ee1=new wo10();
ee.set("图纸","世界");
ee1.set("阿曼尼壁垒","祖阿曼");
ArrayList arr=new ArrayList();
arr.add(ee);
arr.add(ee1);
System.out.println("掉落"+arr.size()+"件");
for(int i=0;i<arr.size();i++)
{System.out.println(arr.get(i));}
arr.remove(ee);
for(int i=0;i<arr.size();i++)
{System.out.println(arr.get(i));}
File f=new File("d:\\dsa.txt");
FileOutputStream out=new FileOutputStream(f);
try{
out.write(ee1.toString().trim().getBytes());
out.close();
}
catch(Exception e){}
}
}
你这样,谁看的懂啊~