Java中的 ByteArrayInputStream markSupported() 方法及示例

markSupported()方法是Java.io.ByteArrayInputStream方法的内置方法，用于测试此输入流是否支持 mark 和 reset 方法。 ByteArrayInputStreamInputStream 的 markSupported 方法总是返回 true

语法：

public boolean markSupported()

参数：该函数不接受任何参数。
返回值：该函数返回一个布尔值。如果此流实例支持 mark 和 reset 方法，则返回 true，否则返回 false。

下面是上述函数的实现：

方案一：

Java

// Java program to implement
// the above function
import java.io.*;
 
public class Main {
    public static void main(String[] args) throws Exception
    {
 
        byte[] buf = { 5, 6, 7, 8, 9 };
 
        // Create new byte array input stream
        ByteArrayInputStream exam
            = new ByteArrayInputStream(buf);
 
        // print bytes
        System.out.println(exam.read());
        System.out.println(exam.read());
        System.out.println(exam.read());
 
        System.out.println("Mark() invocation");
 
        // Use of markSupported
        boolean check = exam.markSupported();
        System.out.println("markSupported() : "
                           + check);
 
        if (exam.markSupported()) {
 
            // Use of reset() method :
            // repositioning the stream to marked positions.
            exam.reset();
 
            System.out.println("\nreset() invoked");
            System.out.println(exam.read());
            System.out.println(exam.read());
        }
        else {
            System.out.println("reset() method not supported.");
        }
    }
}

输出：

5
6
7
Mark() invocation
markSupported() : true

reset() invoked
5
6

方案二：

Java

// Java program to implement
// the above function
import java.io.*;
 
public class Main {
    public static void main(String[] args) throws Exception
    {
 
        byte[] buf = { 1, 2, 3 };
 
        // Create new byte array input stream
        ByteArrayInputStream exam
            = new ByteArrayInputStream(buf);
 
        // print bytes
        System.out.println(exam.read());
        System.out.println(exam.read());
        System.out.println(exam.read());
 
        // Use of markSupported
        boolean check = exam.markSupported();
 
        System.out.println("markSupported() : "
                           + check);
 
        if (exam.markSupported()) {
 
            // Use of reset() method :
            // repositioning the stream to marked positions
            exam.reset();
 
            System.out.println("\nreset() invoked");
            System.out.println(exam.read());
            System.out.println(exam.read());
        }
        else {
            System.out.println("reset() method not supported.");
        }
    }
}

输出：

1
2
3
markSupported() : true

reset() invoked
1
2

参考： https: Java/io/ByteArrayInputStream.html#markSupported()