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Java - ByteArrayInputStream markSupported()
Description
The Java ByteArrayInputStream markSupported() method returns true if the input stream supports mark() and reset() methods invocations. For ByteArrayInputStream the method always returns true.
Declaration
Following is the declaration for java.io.ByteArrayInputStream.markSupported() method −
public boolean markSupported()
Parameters
NA
Return Value
This method returns true for ByteArrayInputStream
Exception
NA
Example 1
The following example shows the usage of Java ByteArrayInputStream markSupported() method. We've created a variable buf as byte[] and initialized with few bytes. We've created a ByteArrayInputStream reference and then initialized it with buf variable. Then we're checking if mark is supported using markSupported() method. We're reading first three bytes using read() method and then using mark() method, we've reset the mark current position and then bytes are read again. Then we've called the reset() method to reset the head to previously marked position and bytes are read again.
package com.tutorialspoint; import java.io.ByteArrayInputStream; import java.io.IOException; public class ByteArrayInputStreamDemo { public static void main(String[] args) throws IOException { byte[] buf = {65, 66, 67, 68, 69}; ByteArrayInputStream bais = null; try { // create new byte array input stream bais = new ByteArrayInputStream(buf); // test support for mark() and reset() methods invocation boolean isMarkSupported = bais.markSupported(); System.out.println("Is mark supported : "+isMarkSupported); // print bytes System.out.println("Byte read "+ bais.read()); System.out.println("Byte read "+ bais.read()); System.out.println("Byte read "+ bais.read()); System.out.println("Mark() invocation"); // mark() invocation; bais.mark(0); System.out.println("Byte read "+ bais.read()); System.out.println("Byte read "+ bais.read()); System.out.println("Reset() invocation"); // reset() invocation bais.reset(); System.out.println("Byte read "+ bais.read()); System.out.println("Byte read "+ bais.read()); } catch(Exception e) { // if I/O error occurs e.printStackTrace(); } finally { if(bais!=null) bais.close(); } } }
Output
Let us compile and run the above program, this will produce the following result −
Is mark supported : true Byte read 65 Byte read 66 Byte read 67 Mark() invocation Byte read 68 Byte read 69 Reset() invocation Byte read 68 Byte read 69
Example 2
The following example shows the usage of Java ByteArrayInputStream markSupported() method. We've created a variable buf as byte[] and initialized with few bytes. We've created a ByteArrayInputStream reference and then initialized it with buf variable. Then we're checking if mark is supported using markSupported() method. We're reading first two bytes using read() method and then using mark() method, we've reset the mark to current position and then bytes are read again. Then we've called the reset() method to reset the head to previously marked position and bytes are read again.
package com.tutorialspoint; import java.io.ByteArrayInputStream; import java.io.IOException; public class ByteArrayInputStreamDemo { public static void main(String[] args) throws IOException { byte[] buf = {65, 66, 67, 68, 69}; ByteArrayInputStream bais = null; try { // create new byte array input stream bais = new ByteArrayInputStream(buf); // test support for mark() and reset() methods invocation boolean isMarkSupported = bais.markSupported(); System.out.println("Is mark supported : "+isMarkSupported); // print bytes System.out.println("Byte read "+ bais.read()); System.out.println("Byte read "+ bais.read()); System.out.println("Mark() invocation"); // mark() invocation; bais.mark(0); System.out.println("Byte read "+ bais.read()); System.out.println("Byte read "+ bais.read()); System.out.println("Byte read "+ bais.read()); System.out.println("Reset() invocation"); // reset() invocation bais.reset(); System.out.println("Byte read "+ bais.read()); System.out.println("Byte read "+ bais.read()); } catch(Exception e) { // if I/O error occurs e.printStackTrace(); } finally { if(bais!=null) bais.close(); } } }
Output
Let us compile and run the above program, this will produce the following result −
Is mark supported : true Byte read 65 Byte read 66 Mark() invocation Byte read 67 Byte read 68 Byte read 69 Reset() invocation Byte read 67 Byte read 68