Learning Java, 4th Edition

Java Statements and Expressions

At the prompt or in a BeanShell script, you can type standard Java statements and expressions. Statements and expressions are all of the normal things that you’d include in a Java method: variable declarations and assignments, method calls, loops, and conditionals. You can declare classes in the usual way if you want to, but BeanShell allows you to write statements outside of a class or method in an unstructured way as well.

You can type statements exactly as they would appear in Java. You also have the option of working in a more scripting-language-like fashion, with “loosely typed” variables and arguments. In other words, you can be lazy and not declare the types of variables that you use (both primitives and objects). BeanShell will still give you an error if you attempt to misuse the actual contents of the variable. If you do declare types of variables or primitives, BeanShell will enforce them.

Here are some examples:

    foo = "Foo";
    four = (2 + 2)*2/2;
    print( foo + " = " + four );   // print() is a bsh command
    // do a loop
    for (i=0; i<5; i++)
        print(i);
    // pop up an AWT frame with a button in it
    button = new JButton("My Button");
    frame = new JFrame("My Frame");
    frame.getContentPane().add( button, "Center" );
    frame.pack();
    frame.setVisible( true );

If you don’t like the idea of “loosening” Java syntax at all, you can turn off this feature of BeanShell with the following command:

    setStrictJava( true );

Imports

By default, BeanShell imports all of the core ...