用RandomAccessFile创建了一个random对象

更新时间：2018-12-01 09:30:56 197次访问

怎么将random的读取位置定位在文件内容的开始处和文件末，运用seek()方法

我按照我的理解写了一个，你看看：
package package1;
import java.io.File;
import java.io.IOException;
import java.io.RandomaccessFile;
import java.io.Serializable;
import java.util.Random;
import java.util.Scanner;
class Point implements Serializable{
int a;
int b;
public Point(int x,int y){
a=x;
b=y;
}
Point()
{
}
public int getA() {
return a;
}
public void setA(int a) {
this.a = a;
}
public int getB() {
return b;
}
public void setB(int b) {
this.b = b;
}
}
public class TestPoint {
public static int count = 0;
public TestPoint()
{
}
public void writeFile() throws IOException
{
File file= new File("info.txt");
if(!file.exists())
file.createNewFile();
//=new Point[10];
Point p = null;
Random random = new Random();
for(int i=1;i<=10;i++){
p= new Point(i,i);
}
try{
RandomaccessFile ra=new RandomAccessFile(file,"rw");
//将对象数组数据写入
for(int i=1;i<10;i++){
ra.writeInt(p.a);
ra.writeInt(p.b);
}
ra.close();
RandomAccessFile raf=new RandomAccessFile(file,"rw");
for(int i=0;i<10;i++){
System.out.println("["+raf.readInt()+","+raf.readInt()+"]"+" ");
}
raf.close();
}catch(IOException e){
e.printStackTrace();
}
}
public void changeFile() throws IOException{
File file= new File("info.txt");
RandomAccessFile ra=new RandomAccessFile(file,"rw");
if(!file.exists())
file.createNewFile();
Point p[]=new Point[11];
for(int i=1;i<10;i++){
p[i]=new Point(i,i);
}
for(int i=1;i<=10;i++){
ra.writeInt(p[i].a);
ra.writeInt(p[i].b);
}
readFile();
System.out.println("请输入10个坐标中你想要该改变的坐标：");
Scanner sc = new Scanner(System.in);
int k=sc.nextInt();
try{
long gf = 0;
gf=(k)*4;
ra.seek(gf);
System.out.println("所要改变的坐标为：");
System.out.println("["+ra.readInt()+","+ra.readInt()+"]");
System.out.println("输入要改变的两个坐标：");
p[k].a=sc.nextInt();
p[k].b=sc.nextInt();
gf=k*4;
//整形为4个内存
ra.seek(gf);
//讲ra定位在k处，
ra.writeInt(p[k].a);
ra.writeInt(p[k].b);
ra.close();
}catch(IOException e){
e.printStackTrace();
}
System.out.println("改变后，文件中的数据为：");
readFile();
}
public void readFile() throws IOException
{
File file= new File("info.txt");
if(!file.exists())
file.createNewFile();
/*try{
RandomAccessFile ra=new RandomAccessFile(file,"rw");
//将对象数组数据写入
for(int i=0;i<10;i++){
ra.writeInt(p[i].a);
ra.writeInt(p[i].b);
}
ra.close();
*/
RandomAccessFile raf=new RandomAccessFile(file,"rw");
System.out.println("文件中的坐标为：");
for(int i=1;i<10;i++){
System.out.println("第"+i+"个坐标为："+"["+raf.readInt()+","+raf.readInt()+"]"+" ");
}
raf.close();
}/*catch(IOException e){
e.printStackTrace();
}
}*/
/**
* @param args
* @throws IOException
*/
public static void main(String[] args) throws IOException {
// TODO Auto-generated method stub
TestPoint t=new TestPoint();
//t.writeFile();
t.changeFile();
}
}