Java 中的 Reader close()方法，示例

原文:https://www . geesforgeks . org/reader-close-method-in-Java-with-examples/

Java 中 Reader 类的 close() 方法用于关闭流，释放流中繁忙的资源(如果有)。该方法有以下结果:

  • If the stream is open, close the stream to release resources.
  • If the stream has been closed, it has no effect.
  • If the stream performs any reading or other similar operations, it will throw IOException when it is closed.

语法:

public abstract void close()

参数:该方法不接受任何参数

返回值:此方法不返回值。

异常:如果在输入输出时出现一些错误，这个方法抛出 IOException。

下面的方法说明了 close()方法的工作原理:

程序 1:

// Java program to demonstrate
// Reader close() 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);
            }

            // Close the stream using close()
            reader.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
// Reader close() 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);

            // Close the stream using close()
            reader.close();
            System.out.println("Stream Closed.");

            // Check if the Reader is
            // ready to be read using ready()
            System.out.println("Is Reader ready "
                               + "to be read"
                               + reader.ready());
        }
        catch (Exception e) {
            System.out.println(e);
        }
    }
}

输出:

Stream Closed.
java.io.IOException: Stream closed

参考:https://docs . Oracle . com/javase/9/docs/API/Java/io/reader . html # close–

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