Use Ddms and add debug message in your application.

DDMS是開發Android所必備的debug tool,它的功能有:

–Devices - Shows the list of devices and AVDs that are connected to ADB.
–Emulator Control - Lets you carry out device functions.
–LogCat - Lets you view system log messages in real time.
–Threads - Shows currently running threads within a VM.
–Heap - Shows heap usage for a VM.
–Allocation Tracker - Shows the memory allocation of objects.
–File Explorer - Lets you explore the device's file system.

紅色是最重要的功能.


[ Using LogCat ]

LogCat is integrated into DDMS, and outputs the messages that you print out using the Log class. 

因為我們要debug程式,所以要了解其用法:

•logcat messages type:
– Verbose
– Debug
– Info
– Warn
– Error

The Log class:

–v(String, String) (verbose) 

–d(String, String) (debug) 

–i(String, String) (information) 

–w(String, String) (warning) 

–e(String, String) (error)

For example: Log.i("MyActivity", "MyClass.getView() — get item number " + position);

output : I/MyActivity( 1557): MyClass.getView() — get item number 1;

知道語法後就可以開始debug了.

[ 改寫程式,加入debug message ]

 package com.firstapp;

import android.app.Activity;

import android.os.Bundle;

import android.util.Log;

import android.widget.TextView;

public class firstapp extends Activity {

    

      public void onCreate(Bundle savedInstanceState) {

          super.onCreate(savedInstanceState);

          TextView tv = new TextView(this);

          tv.setText("Hello, Mark's Android first APP");

          int position=1;

          Log.i("first app","this app- first app.java" + position);

          setContentView(tv);

         

      }            

}

[ Output debug message with logcat]