In this example we are going to see how to use StringWriter. StringWriter is a subclass of java.io.Writer and can be used to write character streams in a String buffer and later can be used to obtain the stream as a String and even obtain the output buffer as a StringBuffer.
Let’s see some examples.
1. Using StringWriter
Let’s see how you can use StringWriter:
StringWriterExample.java:
package com.javacodegeeks.core.string;
import java.io.StringWriter;
public class StringWriterExample {
public static void main(String[] args) {
String str1 = "Hello World";
String str2 =" of JavaCodeGeeks";
StringWriter outputWriter = new StringWriter();
outputWriter.write(str1);
System.out.println(outputWriter.toString());
outputWriter.write(str2);
System.out.println(outputWriter.toString());
outputWriter.append(" "+str1);
System.out.println(outputWriter.toString());
}
}
This will output :
Hello World
Hello World of JavaCodeGeeks
Hello World of JavaCodeGeeks Hello WorldAs you can see from the above example, we’ve basically used two StringWriter class methods : write and append which basically do the same thing, they append a string or a single character to the output stream (the string buffer). And then we’ve used toString to obtain the contents of the output buffer in the form of a String. Easy!
Let’s see another example. Here you can use write method to write a sub string of the output String:
StringWriterExample.java:
package com.javacodegeeks.core.string;
import java.io.StringWriter;
public class StringWriterExample {
public static void main(String[] args) {
String str1 = "Hello World";
String str2 =" of JavaCodeGeeks";
StringWriter outputWriter = new StringWriter();
outputWriter.write(str1,0,8);
System.out.println(outputWriter.toString());
}
}
This will output :
Hello Wo2. Obtain the StringBuffer
Here you can see how you can obtain and use the output buffer of the StringWriter in the form of a StringBuffer.
StringWriterExample.java:
package com.javacodegeeks.core.string;
import java.io.StringWriter;
public class StringWriterExample {
public static void main(String[] args) {
String str1 = "Hello World";
String str2 =" of JavaCodeGeeks";
StringWriter outputWriter = new StringWriter();
outputWriter.write(str1,0,8);
System.out.println(outputWriter.toString());
StringBuffer sbuf = outputWriter.getBuffer();
sbuf.append(str2);
System.out.println(outputWriter.toString());
}
}
This will output :
Hello Wo
Hello Wo of JavaCodeGeeksAs you can see you can obtain the StringBuffer and use it normally. The changes will be reflected in the StringWriter.
3. A simple use case
Here we are going to present a simple use case of StringWriter. In this example we are going to read file and convert its contents to String.
Let’s see how :
StringWriterExample.java:
package com.javacodegeeks.core.string;
import java.io.BufferedReader;
import java.io.FileInputStream;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.Reader;
import java.io.StringWriter;
import java.io.Writer;
public class StringWriterExample {
public static void main(String[] args) throws IOException {
String str1 = stringWriter("F:\\nikos7\\Desktop\\s.txt");
System.out.println(str1);
}
public static String stringWriter(String fileName) throws IOException {
char[] buff = new char[1024];
Writer stringWriter = new StringWriter();
FileInputStream fStream = null;
Reader bReader = null;
try {
fStream = new FileInputStream(fileName);
bReader = new BufferedReader(new InputStreamReader(fStream, "UTF-8"));
int n;
while ((n = bReader.read(buff)) != -1) {
stringWriter.write(buff, 0, n);
}
} finally {
bReader.close();
stringWriter.close();
fStream.close();
}
return stringWriter.toString();
}
}
Ok so in the above program we simple open a file and read chunks of 1024 characters of it at a time. We then write these characters in the StringWriter. When the loop ends we use toString to convert the character stream that we’ve read into a String.
Download Source Code
This was a Java StringWriter Example. You can download the source code of this example here : StringWriterExample.zip
