Why Doesn't PrintWriter Work?

Even though you may call method PrintWriter.println(), you may not get any output. This is because PrintWriter is auto-flush off by default. Check the code below:

 1 public class Test {
 2     public static void main(String[] args) {
 3         OutputStream out1 = System.out;
 4         PrintWriter out = new PrintWriter(out1);
 5         out.println("hello");
 6         System.out.println("text is about to be flushed.");
 7         out.flush();
 8     }
 9 }

The output is as follows:

text is about to be flushed.
hello

To enable auto-flush, you must initialize PrintWriter as follows:

PrintWriter out = new PrintWriter(out1, true);