java基础之IO字符流练习题

文件字节输入/输出流

对象序列化

BufferedReader/PrintWriter

桥转换流

1：Java?中字节流的父类为?InputStream 和?OutputStream;字符流的父类为?Reader和?Writer。以上?4?个类都位于?java.io包中。

2：对象序列化：

(1)为了让某对象能够被序列化，要求其实现?serializable 接口；

(2)为了让该对象某个属性不参与序列化，应当使用?transient修饰符。

3.以下描述正确的是()? ? ??

1. InputStream?和OutputStream?是基于字节流的
2. Reader?和Writer?是基于字符流的
3. Reader?和Writer?是支持对象序列化的
4. PrintWriter?是支持对象序列化的

4.创建一个BufferedOutputStream?的语句为()

1. new?BufferedOutputStream(“out.txt”);
2. new BufferedOutputStream(new?OutputStream(“out.txt”));
3. new BufferedOutputStream(new?FileOutputStream(“out.txt”));
4. new BufferedOutputStream(new?FileInputStream(“out.txt”));

5.仔细阅读以下代码，关于程序描述正确的是（）

package com.by.homeworkIO2;

import java.io.*;

public class Test9 {
????public static void main(String[] args) {

????????try( ?ObjectOutputStream oos=new ObjectOutputStream(new FileOutputStream("file/test.txt",true));
??????????????ObjectInputStream ois=new ObjectInputStream(new FileInputStream("file/test.txt"));){
????????????oos.writeLong(10000L);
????????????oos.flush();
????????????long l=0;
????????????/*while(true){
????????????????try {
?????????????????????l= (long) ois.readObject();
????????????????????System.out.println(l+1);
????????????????} catch (EOFException e) {
????????????????????break;
????????????????}

????????????}*/
????????????oos.writeLong(ois.readLong()+1);
????????????System.out.println(ois.readLong());

????????}catch (FileNotFoundException e){
????????????System.out.println("文件路径有误");
????????}catch (IOException e){
????????????System.out.println("读写有误");
????????} catch (Exception e) {
????????????System.out.println("位置错误");
????????}
????}
}

9：编程：根据提示完成以下代码

?

package com.by.homeworkIO2;

import javax.swing.plaf.basic.BasicDesktopIconUI;
import java.io.File;
import java.io.IOException;
import java.lang.reflect.Field;

public class Test10 {
????public static void main(String[] args) throws IOException {
????????File f=new File("file/hello.txt");
????????System.out.println(f.exists());
????????if (f.exists()){
????????????System.out.println(f.getPath());
????????????System.out.println(f.getAbsolutePath());
????????????System.out.println(f.getCanonicalPath());
????????}
????????System.out.println(f.isFile());
????}
}

10：（字符流、桥转换）完成下面功能：

事先在当前目录下准备好一个 test.txt 的文本文件，要求该文本文件是使用 GBK 编码的多行文本文件。如test.txt ：

package com.by.homeworkIO2;

import java.io.*;

public class Test11GBK {
????public static void main(String[] args) {

????????try (OutputStream os=new FileOutputStream("file/test1.txt");
?????????????InputStream is=new FileInputStream("file/test1.txt");
?????????????OutputStreamWriter osw=new OutputStreamWriter(os,"GBK");
?????????????InputStreamReader isr=new InputStreamReader(is,"GBK");
?????????????PrintWriter pw=new PrintWriter(osw);
?????????????BufferedReader br=new BufferedReader(isr);){
????????????pw.println("床前明月光");
????????????pw.println("疑似地上霜");
????????????pw.println("举头望明月");
????????????pw.println("低头思故乡");
????????????pw.flush();
????????????while(true){
????????????????String str=br.readLine();
????????????????if (str==null){
????????????????????break;
????????????????}
????????????????System.out.println(str);
????????????}
????????}catch (FileNotFoundException e){
????????????System.out.println("文件路径有误");
????????}catch (IOException e){
????????????System.out.println("读写有误");
????????} catch (Exception e) {
????????????throw new RuntimeException(e);
????????}
????}
}

??

利用字节流+桥转换读入这个文本文件，按照行的顺序，以UTF-8 编码方式，写到 test2.txt 文件中。例 ：test2.txt ：

package com.by.homeworkIO2;

import java.io.*;

public class Test11GBK {
????public static void main(String[] args) {

????????try (OutputStream os=new FileOutputStream("file/test1.txt");
?????????????InputStream is=new FileInputStream("file/test1.txt");
?????????????OutputStreamWriter osw=new OutputStreamWriter(os,"UTF-8");
?????????????InputStreamReader isr=new InputStreamReader(is,"UTF-8");
?????????????PrintWriter pw=new PrintWriter(osw);
?????????????BufferedReader br=new BufferedReader(isr);){
????????????pw.println("床前明月光");
????????????pw.println("疑似地上霜");
????????????pw.println("举头望明月");
????????????pw.println("低头思故乡");
????????????pw.flush();
????????????while(true){
????????????????String str=br.readLine();
????????????????if (str==null){
????????????????????break;
????????????????}
????????????????System.out.println(str);
????????????}
????????}catch (FileNotFoundException e){
????????????System.out.println("文件路径有误");
????????}catch (IOException e){
????????????System.out.println("读写有误");
????????} catch (Exception e) {
????????????throw new RuntimeException(e);
????????}
????}
}

11：编程：根据描述完成以下程序：

在当前目录下创建一个 worldcup.txt 的文本文件，其格式如下：

要求：读入该文件的基础上，让用户输入一个年份，输出该年的世界杯冠军。如果该年没有举办世界杯， 则输出“没有举办世界杯”

package com.by.homeworkIO2;

import java.io.BufferedReader;
import java.io.FileNotFoundException;
import java.io.FileReader;
import java.io.IOException;
import java.util.Scanner;

public class Test12WorldCup {
????public static void main(String[] args) {
????????try (
????????????????//创建输入流读取数据
????????????????BufferedReader br = new BufferedReader(new FileReader("file/worldcup.txt"))
????????) { //获取用户输入
????????????Scanner scanner =new Scanner(System.in);
????????????System.out.println("请输入年份：");
????????????String year = scanner.next();
????????????//读取文件内容并比较
????????????boolean flag=false;
????????????while (true){
????????????????String line = br.readLine();
????????????????if (line==null)break;
????????????????String[] strs = line.split("/");
????????????????if (strs[0].equals(year)){
????????????????????flag=true;
????????????????????System.out.println(strs[1]);
????????????????}
????????????}
????????????if (!flag){
????????????????System.out.println("没有举办世界杯");
????????????}
????????} catch (FileNotFoundException e) {
????????????System.out.println("文件找不到");
????????} catch (IOException e) {
????????????System.out.println("IO异常");
????????????e.printStackTrace();
????????} catch (Exception e) {
????????????System.out.println("未知异常");
????????????e.printStackTrace();
????????}
????}
}