一下代码显示如何记录信息。

import android.app.Activity;
import android.os.Bundle;
import android.util.Log;
/*from www.w3cschool.cn*/
public class MainActivity extends Activity {

  private static final String LOG_TAG = "MainActivity";

  @Override
  public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.main);

    Log.d(LOG_TAG, "Log should be deleted");
  }
}

注意

上面的代码使用的是Log.d 方法记录调试信息。

封装log类以创建你自己的记录器

以下代码显示如何封装log类来创建自己的记录器。

布局activity_main.xml文件

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent" >

    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_centerHorizontal="true"
        android:layout_centerVertical="true"
        android:text="@string/hello_world"
        tools:context=".MainActivity" />

</RelativeLayout>

Java代码

package com.java2s.myapplication3.app;
//from www.w3cschool.cn
import android.app.Activity;
import android.os.Bundle;
import android.util.Log;
public class MainActivity extends Activity {

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        Logger.d("Activity Created");
    }

    @Override
    protected void onResume() {
        super.onResume();
        Logger.d("Activity Resume at %d", System.currentTimeMillis());
        Logger.i("It is now %d", System.currentTimeMillis());
    }

    @Override
    protected void onPause() {
        super.onPause();
        Logger.d("Activity Pause at %d", System.currentTimeMillis());
        Logger.w("on pause");
    }
}
class Logger {
    private static final String LOGTAG = "AndroidRecipes";

    private static String getLogString(String format, Object... args) {
        if(args.length == 0) {
            return format;
        }
        return String.format(format, args);
    }
    public static void e(String format, Object... args) {
        Log.e(LOGTAG, getLogString(format, args));
    }

    public static void w(String format, Object... args) {
        Log.w(LOGTAG, getLogString(format, args));
    }

    public static void w(Throwable throwable) {
        Log.w(LOGTAG, throwable);
    }

    public static void i(String format, Object... args) {
        Log.i(LOGTAG, getLogString(format, args));
    }
    public static void d(String format, Object... args) {
        if(!BuildConfig.DEBUG)
            return;
        Log.d(LOGTAG, getLogString(format, args));
    }

    public static void v(String format, Object... args) {
        if(!BuildConfig.DEBUG)
            return;

        Log.v(LOGTAG, getLogString(format, args));
    }
}