Part III: Doing More with Eclipse in Java

Printer QR Code 2d barcode in Java Part III: Doing More with Eclipse

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ack in 2002, I wrote Java & XML For Dummies As part of my research, I joined a local Special Interest Group on XML The meetings were interesting People argued for hours over the most esoteric issues Should a certain piece of information be expressed as an element attribute or should that information be the element s content The term religious wars came to mind, but I never uttered that term aloud in any of the group s discussions Every field of study has its religious wars In the world of Java programming, people argue over all kinds of things For instance, you want a program to get a small piece of information at runtime Where do you put this piece of information Do you make it a program argument or a virtual machine argument And what if you don t know the difference between these two kinds of arguments (And what if you don t care ) This chapter covers program arguments, virtual machine arguments, and a few other tricks The chapter tells you how to use each of these things in Eclipse

A run configuration is a set of guidelines that Eclipse uses for running a particular Java program A particular run configuration stores the name of a main class, the values stored in the main method s args parameter, the JRE version to be used, the CLASSPATH, and many other facts about a program s anticipated run

Whenever you run a program, Eclipse uses one run configuration or another In the previous chapters, Eclipse uses a default run configuration But in this chapter, you create customized run configurations Here s how you do it: 1 Select a class that contains a main method You can select any class you want Select this class by clicking a branch in the Package Explorer or the Outline view Alternatively, you can click the class s editor tab 2 On Eclipse s menu bar, choose Run Run The big Run dialog appears (See Figure 14-1) Starting with Eclipse version 31, the Run menu has two Run items that look almost identical One of the Run items has an ellipsis (three dots) and the other Run item doesn t In this example, the Run item you want is the one with the ellipsis If, after choosing Run Run, you don t get the dialog shown in Figure 14-1, then you ve chosen the wrong Run item 3 In the Configurations pane (on the left side of the Run dialog), doubleclick the Java Application branch Double-clicking Java Application creates a brand new item The item s name comes from whatever class you selected in Step 1

When I selected a class in Step 1, the class s name was DeleteEvidence So in Figure 14-2, the Configurations pane has a new item named DeleteEvidence This DeleteEvidence item represents a brand-new run configuration

Eclipse s run configurations come in five different flavors In Eclipse version 30, these flavors are named Java Applet, Java Application, JUnit, JUnit Plugin Test, and Run-time Workbench (Again, see Figure 14-2) By the time version 31 rolled in, someone had replaced Run-time Workbench with Eclipse Application Anyway, each flavor of run configuration stores certain kinds of information For example, a Java Applet configuration stores applet tag parameters things like Width and Height (See Figure 14-3) A Java Application configuration doesn t store any applet tag parameters because a stand-alone application doesn t use an applet tag

Listing 14-1 contains a very useful program The program deletes a file of your choosing To choose a file, you send the file s name to the args parameter

Listing 14-1: