| <html> |
| <head> |
| <title>Basic Dalvik VM Invocation</title> |
| </head> |
| |
| <body> |
| <h1>Basic Dalvik VM Invocation</h1> |
| |
| <p> |
| On an Android device, the Dalvik virtual machine usually executes embedded |
| in the Android application framework. It's also possible to run it directly, |
| just as you would a virtual machine on your desktop system. |
| </p><p> |
| After compiling your Java language sources, convert and combine the .class |
| files into a DEX file, and push that to the device. Here's a simple example: |
| |
| </p><p><code> |
| % <font color="green">echo 'class Foo {'\</font><br> |
| > <font color="green">'public static void main(String[] args) {'\</font><br> |
| > <font color="green">'System.out.println("Hello, world"); }}' > Foo.java</font><br> |
| % <font color="green">javac Foo.java</font><br> |
| % <font color="green">dx --dex --output=foo.jar Foo.class</font><br> |
| % <font color="green">adb push foo.jar /sdcard</font><br> |
| % <font color="green">adb shell dalvikvm -cp /sdcard/foo.jar Foo</font><br> |
| Hello, world |
| </code> |
| </p><p> |
| The <code>-cp</code> option sets the classpath. The initial directory |
| for <code>adb shell</code> may not be what you expect it to be, so it's |
| usually best to specify absolute pathnames. |
| |
| </p><p> |
| The <code>dx</code> command accepts lists of individual class files, |
| directories, or Jar archives. When the <code>--output</code> filename |
| ends with <code>.jar</code>, <code>.zip</code>, or <code>.apk</code>, |
| a file called <code>classes.dex</code> is created and stored inside the |
| archive. |
| </p><p> |
| Run <code>adb shell dalvikvm -help</code> to see a list of command-line |
| options. |
| </p><p> |
| |
| |
| |
| <h2>Using a debugger</h2> |
| |
| <p> |
| You can debug stand-alone applications with any JDWP-compliant debugger. |
| There are two basic approaches. |
| </p><p> |
| The first way is to connect directly through TCP. Add, to the "dalvikvm" |
| invocation line above, an argument like: |
| </p><p> |
| <code> -agentlib:jdwp=transport=dt_socket,address=8000,server=y,suspend=y</code> |
| </p><p> |
| This tells the VM to wait for a debugger to connect to it on TCP port 8000. |
| You need to tell adb to forward local port 8000 to device port 8000: |
| </p><p> |
| <code>% <font color="green">adb forward tcp:8000 tcp:8000</font></code> |
| </p><p> |
| and then connect to it with your favorite debugger (using <code>jdb</code> |
| as an example here): |
| </p><p> |
| <code>% <font color="green">jdb -attach localhost:8000</font></code> |
| </p><p> |
| When the debugger attaches, the VM will be in a suspended state. You can |
| set breakpoints and then tell it to continue. |
| |
| |
| </p><p> |
| You can also connect through DDMS, like you would for an Android application. |
| Add, to the "dalvikvm" command line: |
| </p><p> |
| <code> -agentlib:jdwp=transport=dt_android_adb,suspend=y,server=y</code> |
| </p><p> |
| Note the <code>transport</code> has changed, and you no longer need to |
| specify a TCP port number. When your application starts, it will appear |
| in DDMS, with "?" as the application name. Select it in DDMS, and connect |
| to it as usual, e.g.: |
| </p><p> |
| <code>% <font color="green">jdb -attach localhost:8700</font></code> |
| </p><p> |
| Because command-line applications don't include the client-side |
| DDM setup, features like thread monitoring and allocation tracking will not |
| be available in DDMS. It's strictly a debugger pass-through in this mode. |
| </p><p> |
| See <a href="debugger.html">Dalvik Debugger Support</a> for more information |
| about using debuggers with Dalvik. |
| |
| |
| </p></p> |
| <address>Copyright © 2009 The Android Open Source Project</address> |
| |
| </body> |
| </html> |
