java reader示例,Java Reader read()用法及代码示例
Java中Reader类的read()方法用于从流中读取单个字符。此方法将流阻塞到：
它已从流中获取了一些输入。
发生了一些IOException
阅读时已到达流的末尾。
该方法被声明为抽象方法。这意味着，如果在读取字符时需要更改所需的操作，则Reader抽象类的子类应重写此方法。
用法:
public abstract int read()
参数：此方法不接受任何参数
返回值：此方法返回一个整数值，该整数值是从流中读取的整数值。范围从0到65535。如果未读取任何字符，则返回-1。
异常：如果输入输出时发生某些错误，则此方法将引发IOException。
下面的方法说明了read()方法的用法方式：
示例1:
// Java program to demonstrate
// Reader read() method
import java.io.*;
import java.util.*;
class GFG {
public static void main(String[] args)
{
try {
String str = "GeeksForGeeks";
// Create a Reader instance
Reader reader
= new StringReader(str);
// Get the character
// to be read from the stream
int ch;
// Read the first 5 characters
// to this reader using read() method
// This will put the str in the stream
// till it is read by the reader
for (int i = 0; i < 5; i++) {
ch = reader.read();
System.out.println("\nInteger value "
+ "of character read: "
+ ch);
System.out.println("Actual "
+ "character read: "
+ (char)ch);
}
reader.close();
}
catch (Exception e) {
System.out.println(e);
}
}
}
输出：
Integer value of character read: 71
Actual character read: G
Integer value of character read: 101
Actual character read: e
Integer value of character read: 101
Actual character read: e
Integer value of character read: 107
Actual character read: k
Integer value of character read: 115
Actual character read: s
示例2:
// Java program to demonstrate
// Reader read() method
import java.io.*;
import java.util.*;
class GFG {
public static void main(String[] args)
{
try {
String str = "GeeksForGeeks";
// Create a Reader instance
Reader reader
= new StringReader(str);
// Get the character
// to be read from the stream
int ch;
// Read the first character
// to this reader using read() method
// This will put the str in the stream
// till it is read by the reader
ch = reader.read();
System.out.println("\nInteger value "
+ "of character read: "
+ ch);
System.out.println("Actual "
+ "character read: "
+ (char)ch);
reader.close();
}
catch (Exception e) {
System.out.println(e);
}
}
}
输出：
Integer value of character read: 71
Actual character read: G