Java standard stream
In this chapter you will learn:
Java standard output stream
static PrintStream out wraps the "standard" output stream.
We usually use the standard output stream to output information to the console.
public class Main {
// j a va 2s. c om
public static void main(String args[]) {
System.out.println("Java2s.c o m");
}
}
The output:
Java standard input stream
static InputStream in wraps the "standard" input stream.
We can use the standard input stream to read user input from console window.
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
/* j av a 2 s . c om*/
public class Main {
public static void main(String[] args) {
try {
// read value from console window
BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
System.out.println("Please enter a value");
System.out.println(br.readLine());
} catch (IOException ioe) {
System.out.println("IO Error :" + ioe);
System.exit(0);
}
}
}
The following code reads integer value from console window.
It reads the value as a string type first then convert it to integer
with Integer.parseInt method.
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
/*ja v a2 s. co m*/
public class Main {
public static void main(String[] args) {
try {
BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
System.out.println("Please enter an integer value");
String input = br.readLine();
System.out.println("input:" + input);
System.out.println("convert to integer:" + Integer.parseInt(input));
} catch (NumberFormatException ne) {
System.out.println("Invalid value" + ne);
System.exit(0);
} catch (IOException ioe) {
System.out.println("IO Error :" + ioe);
System.exit(0);
}
}
}
Next chapter...
What you will learn in the next chapter:
- Get/set system property
- Predefined System properties
- Get the system properties
- Set a system properties
- Get the system environment
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