Java中的 PushbackReader ready() 方法和示例

Java中PushbackReader类的ready()方法用于检查这个PushbackReader是否准备好被读取。它返回一个布尔值，说明阅读器是否准备好。

句法：

public void ready()

参数：此方法不接受任何参数

返回值：此方法返回一个布尔值，该值指示此 PushbackReader 是否已准备好读取。如果准备好，则返回 true。否则返回false。

异常：如果输入输出时发生错误，此方法将抛出IOException 。

下面的方法说明了 ready() 方法的工作：

方案一：

// Java program to demonstrate
// PushbackReader ready() 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);
  
            // Check if the PushbackReader is
            // ready to be read using ready()
            System.out.println("Is PushbackReader ready "
                               + "to be read: "
                               + pushbackReader.ready());
  
            // Close the stream using ready()
            pushbackReader.close();
            System.out.println("Stream Closed.");
        }
        catch (Exception e) {
            System.out.println(e);
        }
    }
}

输出：

Is PushbackReader ready to be read: true
Stream Closed.

方案二：

// Java program to demonstrate
// PushbackReader ready() 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);
  
            // Check if the PushbackReader is
            // ready to be read using ready()
            System.out.println("Is PushbackReader ready "
                               + "to be read: "
                               + pushbackReader.ready());
  
            // Close the stream
            pushbackReader.close();
            System.out.println("Stream Closed.");
        }
        catch (Exception e) {
            System.out.println(e);
        }
    }
}

输出：

Is PushbackReader ready to be read: true
Stream Closed.

参考： https://docs.oracle.com/javase/9/docs/api/ Java/io/PushbackReader.html#ready–