Java 中的推读 Reader read()方法,示例
原文:https://www . geesforgeks . org/puback reader-read-method-in-Java-with-examples/
Java 中 推读类 的 read() 方法用于从流中读取单个字符。这个方法阻塞流直到:
- It takes some input from the stream.
- Some IOException occurred.
- It has reached the end of the stream when reading.
语法:
public int read()
参数:该方法不接受任何参数
返回值:该方法返回一个整数值,它是从流中读取的整数值。范围可以从 0 到 65535。否则,如果未读取任何字符,则返回-1。
异常:如果输入输出时出现错误,该方法抛出异常。
下面的方法说明了 read()方法的工作原理:
程序 1:
// Java program to demonstrate
// PushbackReader read() method
import java.io.*;
import java.util.*;
class GFG {
public static void main(String[] args)
{
try {
// Initializing a StringReader
// and PushbackReader
String s = "GeeksForGeeks";
StringReader stringReader
= new StringReader(s);
PushbackReader pushbackReader
= new PushbackReader(stringReader);
// 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 = pushbackReader.read();
System.out.println("\nInteger value "
+ "of character read: "
+ ch);
System.out.println("Actual "
+ "character read: "
+ (char)ch);
}
// Close the stream using read()
pushbackReader.close();
System.out.println("Stream Closed.");
}
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
Stream Closed.
程序二:
// Java program to demonstrate
// PushbackReader read() method
import java.io.*;
import java.util.*;
class GFG {
public static void main(String[] args)
{
try {
// Initializing a StringReader
// and PushbackReader
String s = "GFG";
StringReader stringReader
= new StringReader(s);
PushbackReader pushbackReader
= new PushbackReader(stringReader);
// Get the character
// to be read from the stream
int ch;
// Read the first 2 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 < 2; i++) {
ch = pushbackReader.read();
System.out.println("\nInteger value "
+ "of character read: "
+ ch);
System.out.println("Actual "
+ "character read: "
+ (char)ch);
}
// Close the stream
pushbackReader.close();
System.out.println("Stream Closed.");
}
catch (Exception e) {
System.out.println(e);
}
}
}
输出:
Integer value of character read: 71
Actual character read: G
Integer value of character read: 70
Actual character read: F
Stream Closed.
参考:https://docs . Oracle . com/javase/9/docs/API/Java/io/puback reader . html # read–
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