第四周作业，图的表示

package test;

import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.FileReader;
import java.io.IOException;
import java.io.OutputStreamWriter;

public class test {

public static void main(String[] args) {
try {
FileReader in = new FileReader("e:\\tinyG.txt");
BufferedReader bl = new BufferedReader(in);
int tempchar;
String str = "";
str = bl.readLine();
int x = Integer.parseInt(str);
str = bl.readLine();
int E = Integer.parseInt(str);
int[][] g = new int[x][x];
str = "";
int a = 0, b = 0;
while ((tempchar = bl.read()) != -1)
{
str = str + (char) tempchar;
if ((char) tempchar == ' ')
{
a = Integer.parseInt(str.trim());
str = "";
}
if ((char) tempchar == '\n')
{
b = Integer.parseInt(str.trim());
g[a][b] = 1;
g[b][a] = 1;
str = "";
}
}

bl.close();
in.close();

FileOutputStream fos = new FileOutputStream("e:\\tinyG_matrix.txt");
OutputStreamWriter osw = new OutputStreamWriter(fos, "gb2312");
BufferedWriter bw = new BufferedWriter(osw);
str="";
System.out.println("得  到  图  的  邻  接  矩  阵  为 ： ");
for (int i = 0; i < x; i++)
{
for (int j = 0; j < x; j++)
{
System.out.print(g[i][j]+"   ");
str=str+Integer.toString(g[i][j]);
if(j==12){
System.out.println();
bw.write(str);
bw.newLine();
str="";
}
}
}

bw.close();
osw.close();

}
catch (NumberFormatException e)
{
e.printStackTrace();
}
catch (FileNotFoundException e)
{
e.printStackTrace();
}
catch (IOException e)
{
e.printStackTrace();
}

}
}