Java - Writer append(CharSequence csq) method

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Description

The Java Writer append(CharSequence csq) method appends the specified character sequence to this writer.

Declaration

Following is the declaration for java.io.Writer.append(CharSequence csq) method.

public Writer append(CharSequence csq)

Parameters

csq − The character sequence to append. If csq is null, then the four characters "null" are appended to this writer.

Return Value

This method returns the current writer.

Exception

IOException − If an I/O error occurs.

Example - Usage of Writer append(CharSequence csq) method

The following example shows the usage of Writer append(CharSequence csq) method.

WriterDemo.java

package com.tutorialspoint;

import java.io.IOException;
import java.io.PrintWriter;
import java.io.Writer;

public class WriterDemo {
   public static void main(String[] args) {
      CharSequence csq = "Hello World!";

      // create a new writer
      Writer writer = new PrintWriter(System.out);

      try {
         // append a sequence and change line
         writer.append("This is an example\n");

         // flush the writer
         writer.flush();

         // append a new sequence
         writer.append(csq);

         // flush the writer to see the result
         writer.flush();

      } catch (IOException ex) {
         ex.printStackTrace();
      }
   }
}

Output

Let us compile and run the above program, this will produce the following result −

This is an example
Hello World!

Example - Append a String

The following example shows the usage of Writer append(CharSequence csq) method.

WriterDemo.java

package com.tutorialspoint;

import java.io.StringWriter;

public class WriterDemo {
   public static void main(String[] args) {
      StringWriter writer = new StringWriter();

      CharSequence csq = "Hello, World!";
      writer.append(csq);

      System.out.println("Output: " + writer.toString());
   }
}

Output

Let us compile and run the above program, this will produce the following result−

Output: Hello, World!

Explanation

• "Hello, World!" (a String, which is a CharSequence) is appended to the writer.

• The entire string is stored in the buffer.

Example - Append a StringBuilder and Handle null

The following example shows the usage of Writer append(CharSequence csq) method.

WriterDemo.java

package com.tutorialspoint;

import java.io.StringWriter;

public class WriterDemo {
   public static void main(String[] args) {
      StringWriter writer = new StringWriter();

      StringBuilder sb = new StringBuilder("Java");
      writer.append(sb);
      writer.append(" is fun!");

      CharSequence nullSeq = null;
      writer.append(nullSeq);  // Will append "null"

      System.out.println("Final Output: " + writer.toString());
   }
}

Output

Let us compile and run the above program, this will produce the following result−

Final Output: Java is fun!null

Explanation

• Appends "Java" from a StringBuilder.

• Then appends " is fun!".

• Then appends a null CharSequence, which results in "null" being added.