ByteBuffer getChar() method in Java with Examples - GeeksforGeeks

22 Jul, 2019
The getChar() method of java.nio.ByteBuffer class is used to get method for reading a char value
Reads the next two bytes at this buffer’s current position, composing them into a char value according to the current byte order, and then increments the position by two.
Syntax:
public abstract char getChar()
Return Value: This method returns the char value at the buffer’s current position
Throws: This method throws BufferUnderflowException – If the buffer’s current position is not smaller than its limit, then this exception is thrown.
Below are the examples to illustrate the getChar() method:
Examples 1:
// Java program to demonstrate// getChar() method  import java.nio.*;import java.util.*;  public class GFG {      public static void main(String[] args)    {          // Declaring the capacity of the ByteBuffer        int capacity = 50;          // Creating the ByteBuffer        try {              // creating object of ByteBuffer            // and allocating size capacity            ByteBuffer bb = ByteBuffer.allocate(capacity);              // putting the string in the bytebuffer            bb.asCharBuffer().put("Geeks");              // rewind the Bytebuffer            bb.rewind();              // Declaring the variable            char c;              // print the ByteBuffer            System.out.println("Original ByteBuffer: ");            while ((c = bb.getChar()) != 0)                System.out.print(c + " ");              // rewind the Bytebuffer            bb.rewind();              // Reads the char at this buffer's current position            // using getChar() method            char value = bb.getChar();              // print the char value            System.out.println("\n\nByte Value: " + value);              // Reads the  char at this buffer's next position            // using getChar() method            char value1 = bb.getChar();              // print the char value            System.out.print("\nNext Byte Value: " + value1);        }          catch (IllegalArgumentException e) {              System.out.println("\nException Thrown: " + e);        }          catch (ReadOnlyBufferException e) {              System.out.println("\nException Thrown: " + e);        }          catch (BufferUnderflowException e) {              System.out.println("\nException Thrown: " + e);        }    }}
Original ByteBuffer: 
G e e k s 

Byte Value: G

Next Byte Value: e

Examples 2:
// Java program to demonstrate// getChar() method  import java.nio.*;import java.util.*;  public class GFG {      public static void main(String[] args)    {          // Declaring the capacity of the ByteBuffer        int capacity = 8;          // Creating the ByteBuffer        try {              // creating object of ByteBuffer            // and allocating size capacity            ByteBuffer bb = ByteBuffer.allocate(capacity);              // putting the string in the bytebuffer            bb.asCharBuffer().put("abc");              // rewind the Bytebuffer            bb.rewind();              // Declaring the variable            char c;              // print the ByteBuffer            System.out.print("Original ByteBuffer: ");            while ((c = bb.getChar()) != 0)                System.out.print(c + " ");              // rewind the Bytebuffer            bb.rewind();              // Reads the char at this buffer's current position            // using getChar() method            char value = bb.getChar();              // print the char value            System.out.println("\n\nFirst char Value: " + value);              // Reads the  char at this buffer's next position            // using getChar() method            char value1 = bb.getChar();              // print the char value            System.out.println("\nSecond char Value: " + value1);              // Reads the  char at this buffer's next position            // using getChar() method            char value2 = bb.getChar();              // print the char value            System.out.println("\nThird char Value: " + value2);              // Reads the  char at this buffer's next position            // using getChar() method            System.out.print("\nsince the buffer current position is incremented");            System.out.print(" to greater than its limit ");            char value3 = bb.getChar();            char value4 = bb.getChar();        }          catch (BufferOverflowException e) {              System.out.println("\nException Thrown: " + e);        }          catch (ReadOnlyBufferException e) {              System.out.println("\nException Thrown: " + e);        }          catch (BufferUnderflowException e) {              System.out.println("\nException Thrown: " + e);        }    }}
Original ByteBuffer: a b c 

First char Value: a

Second char Value: b

Third char Value: c

since the buffer current position is incremented to greater than its limit 
Exception Thrown: java.nio.BufferUnderflowException

The get(int index) method of ByteBuffer is used to reads two bytes at the given index, composing them into a char value according to the current byte order.
Syntax:
public abstract char getChar(int index)
Parameters: This method takes index (The index from which the Byte will be read) as a parameter.
Return Value: This method returns the char value at the given index.
Exception: This method throws IndexOutOfBoundsException. If index is negative or not smaller than the buffer’s limit this exception is thrown.
Below are the examples to illustrate the get(int index) method:
Examples 1:
// Java program to demonstrate// getChar() method  import java.nio.*;import java.util.*;  public class GFG {      public static void main(String[] args)    {          // Declaring the capacity of the ByteBuffer        int capacity = 50;          // Creating the ByteBuffer        try {              // creating object of ByteBuffer            // and allocating size capacity            ByteBuffer bb = ByteBuffer.allocate(capacity);              // putting the string in the bytebuffer            bb.asCharBuffer().put("abc");              // rewind the Bytebuffer            bb.rewind();              // Declaring the variable            char c;              // print the ByteBuffer            System.out.print("Original ByteBuffer: ");            while ((c = bb.getChar()) != 0)                System.out.print(c + " ");              // rewind the Bytebuffer            bb.rewind();              // Reads the char at this buffer's at index 0            // using getChar() method            char value0 = bb.getChar(0);              // print the char value            System.out.println("\n\nchar Value at index 0: "                               + value0);              // Reads the  char at this buffer's at index 2            // using getChar() method            char value1 = bb.getChar(2);              // print the char value            System.out.println("\nchar Value at index 2: "                               + value1);              // Reads the  char at this buffer's at index 4            // using getChar() method            char value2 = bb.getChar(4);              // print the char value            System.out.println("\nchar Value at index 4: "                               + value2);        }          catch (IllegalArgumentException e) {              System.out.println("\nException Thrown: " + e);        }          catch (ReadOnlyBufferException e) {              System.out.println("\nException Thrown: " + e);        }          catch (BufferUnderflowException e) {              System.out.println("\nException Thrown: " + e);        }    }}
Original ByteBuffer: a b c 

char Value at index 0: a

char Value at index 2: b

char Value at index 4: c

Examples 2:
// Java program to demonstrate// getChar() method  import java.nio.*;import java.util.*;  public class GFG {      public static void main(String[] args)    {          // Declaring the capacity of the ByteBuffer        int capacity = 50;          // Creating the ByteBuffer        try {              // creating object of ByteBuffer            // and allocating size capacity            ByteBuffer bb = ByteBuffer.allocate(capacity);              // putting the string in the bytebuffer            bb.asCharBuffer().put("abc");              // rewind the Bytebuffer            bb.rewind();              // Declaring the variable            char c;              // print the ByteBuffer            System.out.print("Original ByteBuffer: ");            while ((c = bb.getChar()) != 0)                System.out.print(c + " ");              // rewind the Bytebuffer            bb.rewind();              // Reads the char at this buffer's at index 0            // using getChar() method            char value0 = bb.getChar(0);              // print the char value            System.out.println("\n\nchar Value at index 0: "                               + value0);              // Reads the  char at this buffer's at index 2            // using getChar() method            char value1 = bb.getChar(2);              // print the char value            System.out.println("\nchar Value at index 2: "                               + value1);              // Reads the  char at this buffer's at index 4            // using getChar() method            System.out.println("\nTrying to get the char"                               + " at negative index ");            char value2 = bb.getChar(-4);        }          catch (IndexOutOfBoundsException e) {              System.out.println("\nException Thrown: "                               + e);        }          catch (ReadOnlyBufferException e) {              System.out.println("\nException Thrown: "                               + e);        }          catch (BufferUnderflowException e) {              System.out.println("\nException Thrown: "                               + e);        }    }}
Original ByteBuffer: a b c 

char Value at index 0: a

char Value at index 2: b

Trying to get the char at a negative index 

Exception Thrown: java.lang.IndexOutOfBoundsException

Reference:
https://docs.oracle.com/javase/9/docs/api/java/nio/ByteBuffer.html#getChar–
https://docs.oracle.com/javase/9/docs/api/java/nio/ByteBuffer.html#getChar-int-
Vijay Sirra
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