Writing Your First Java Program - Java 7 for Absolute Beginners - page 10

Listing 1-3: Reading arguments

package com.apress.java7forabsolutebeginners;

public class Hello {

public static void main(String[] args) {
System.out.println("Hello, " + args[0] + "!");
}

}

■ Note Computers start counting at 0 rather than 1. Consequently, the first member of an array can be found at
0. Typing args[1] here generates an out-of-bounds exception, by which Java means that it expects to find two
strings, but you provided only one. You'll quickly get used to computers starting their counting at 0.

System.out.println accepts a single String object as its argument. In this case, we've got three
String objects, but the plus signs concatenate them together to create a single string, satisfying the
requirement (for just one string) of the println method. The plus sign is Java's string concatenation
operator (in addition to being a plus sign when used for mathematical operations). We cover operators
in Chapter 4, “Operators.”
To provide a value for the argument in Eclipse, follow these steps:
1.

From the Run menu, choose Run Configurations. The Run Configurations
window appears. Figure 1.6 shows the Run Configurations window.

Figure 1-6. The Run Configurations window.

2. In the Arguments tab, type your name.

3. Click the Run button.