public static class hello {
　　public void main(String args[]){
　　　　System.out.println("Hello Android");
　　}
}

dx --dex --output=hello.dex hello.class

package com.yin.system_analysis; 
import java.io.File; 
import java.io.IOException; 
import java.io.InputStream; 
import android.app.Activity; 
import android.os.Bundle; 
import android.util.Log; 
import android.view.View; 
import android.view.View.OnClickListener; 
import android.widget.Button; 
import android.widget.TextView; 
public class MainActivity extends Activity { 
 private final static String[] ARGS = {"ls","-l"}; 
 private final static String TAG = "com.yin.system"; 
 Button mButton; 
 TextView myTextView; 
 public void onCreate(Bundle savedInstanceState) { 
  super.onCreate(savedInstanceState); 
  setContentView(R.layout.main); 
  mButton = (Button) findViewById(R.id.myButton); 
  myTextView = (TextView) findViewById(R.id.textView); 
  mButton.setOnClickListener(new OnClickListener() { 
   public void onClick(View v) { 
    myTextView.setText(getResult()); 
   } 
  }); 
 } 
 public String getResult(){ 
   ShellExecute cmdexe = new ShellExecute ( ); 
   String result=""; 
   try { 
   result = cmdexe.execute(ARGS, "/"); 
  } catch (IOException e) { 
   Log.e(TAG, "IOException"); 
   e.printStackTrace(); 
  } 
  return result; 
 } 
 private class ShellExecute { 
  /*
   * args[0] : shell 命令 如"ls" 或"ls -1";
   * args[1] : 命令执行路径 如"/" ;
   */ 
  public String execute ( String [] cmmand,String directory) 
  throws IOException { 
  String result = "" ; 
  try { 
  ProcessBuilder builder = new ProcessBuilder(cmmand); 
  if ( directory != null ) 
  builder.directory ( new File ( directory ) ) ; 
  builder.redirectErrorStream (true) ; 
  Process process = builder.start ( ) ; 
  //得到命令执行后的结果 
  InputStream is = process.getInputStream ( ) ; 
  byte[] buffer = new byte[1024] ; 
  while ( is.read(buffer) != -1 ) { 
  result = result + new String (buffer) ; 
  } 
  is.close ( ) ; 
  } catch ( Exception e ) { 
   e.printStackTrace ( ) ; 
  } 
  return result ; 
  } 
 } 
}