1 <html> 2 <head> 3 <title>Basic Dalvik VM Invocation</title> 4 </head> 5 6 <body> 7 <h1>Basic Dalvik VM Invocation</h1> 8 9 <p> 10 On an Android device, the Dalvik virtual machine usually executes embedded 11 in the Android application framework. It's also possible to run it directly, 12 just as you would a virtual machine on your desktop system. 13 </p><p> 14 After compiling your Java language sources, convert and combine the .class 15 files into a DEX file, and push that to the device. Here's a simple example: 16 17 </p><p><code> 18 % <font color="green">echo 'class Foo {'\</font><br> 19 > <font color="green">'public static void main(String[] args) {'\</font><br> 20 > <font color="green">'System.out.println("Hello, world"); }}' > Foo.java</font><br> 21 % <font color="green">javac Foo.java</font><br> 22 % <font color="green">dx --dex --output=foo.jar Foo.class</font><br> 23 % <font color="green">adb push foo.jar /sdcard</font><br> 24 % <font color="green">adb shell dalvikvm -cp /sdcard/foo.jar Foo</font><br> 25 Hello, world 26 </code> 27 </p><p> 28 The <code>-cp</code> option sets the classpath. The initial directory 29 for <code>adb shell</code> may not be what you expect it to be, so it's 30 usually best to specify absolute pathnames. 31 32 </p><p> 33 The <code>dx</code> command accepts lists of individual class files, 34 directories, or Jar archives. When the <code>--output</code> filename 35 ends with <code>.jar</code>, <code>.zip</code>, or <code>.apk</code>, 36 a file called <code>classes.dex</code> is created and stored inside the 37 archive. 38 </p><p> 39 Run <code>adb shell dalvikvm -help</code> to see a list of command-line 40 options. 41 </p><p> 42 43 44 45 <h2>Using a debugger</h2> 46 47 <p> 48 You can debug stand-alone applications with any JDWP-compliant debugger. 49 There are two basic approaches. 50 </p><p> 51 The first way is to connect directly through TCP. Add, to the "dalvikvm" 52 invocation line above, an argument like: 53 </p><p> 54 <code> -agentlib:jdwp=transport=dt_socket,address=8000,server=y,suspend=y</code> 55 </p><p> 56 This tells the VM to wait for a debugger to connect to it on TCP port 8000. 57 You need to tell adb to forward local port 8000 to device port 8000: 58 </p><p> 59 <code>% <font color="green">adb forward tcp:8000 tcp:8000</font></code> 60 </p><p> 61 and then connect to it with your favorite debugger (using <code>jdb</code> 62 as an example here): 63 </p><p> 64 <code>% <font color="green">jdb -attach localhost:8000</font></code> 65 </p><p> 66 When the debugger attaches, the VM will be in a suspended state. You can 67 set breakpoints and then tell it to continue. 68 69 70 </p><p> 71 You can also connect through DDMS, like you would for an Android application. 72 Add, to the "dalvikvm" command line: 73 </p><p> 74 <code> -agentlib:jdwp=transport=dt_android_adb,suspend=y,server=y</code> 75 </p><p> 76 Note the <code>transport</code> has changed, and you no longer need to 77 specify a TCP port number. When your application starts, it will appear 78 in DDMS, with "?" as the application name. Select it in DDMS, and connect 79 to it as usual, e.g.: 80 </p><p> 81 <code>% <font color="green">jdb -attach localhost:8700</font></code> 82 </p><p> 83 Because command-line applications don't include the client-side 84 DDM setup, features like thread monitoring and allocation tracking will not 85 be available in DDMS. It's strictly a debugger pass-through in this mode. 86 </p><p> 87 See <a href="debugger.html">Dalvik Debugger Support</a> for more information 88 about using debuggers with Dalvik. 89 90 91 </p></p> 92 <address>Copyright © 2009 The Android Open Source Project</address> 93 94 </body> 95 </html> 96
