Android代碼片段

判斷當前應用是否是最上層的應用：
 
public static boolean isTopApp(Context context) {
        ActivityManager activityManager = (ActivityManager) context
                .getSystemService(ACTIVITY_SERVICE);
        List<ActivityManager.RunningTaskInfo> tasks = activityManager
                .getRunningTasks(5);
        if (tasks == null || tasks.isEmpty()) {
            return false;
        }
        RunningTaskInfo task = tasks.get(0);
        String taskPackageName = task.topActivity.getPackageName();// task任務的package包名
        System.out.println(taskPackageName);
        // System.out.println(task.topActivity.getClassName());
        // System.out.println(task.baseActivity.getClassName());
        return context.getPackageName().equals(taskPackageName);
    }

本機IP地址：
Enumeration<NetworkInterface> networkInfo = NetworkInterface
                        .getNetworkInterfaces();
                while (networkInfo.hasMoreElements())
                {
                    NetworkInterface intf = networkInfo.nextElement();
                    Enumeration<InetAddress> intfAddress = intf
                            .getInetAddresses();
                    while (intfAddress.hasMoreElements())
                    {
                        InetAddress inetAddress = intfAddress.nextElement();
                        if (!inetAddress.isLoopbackAddress())
                        {
                            ip = inetAddress.getHostAddress().toString();
                        }
                    }
                }

屏幕分辨率及其相關屬性：
DisplayMetrics dm = new DisplayMetrics();
activity.getWindowManager().getDefaultDisplay().getMetrics(dm);
System.out.println(dm.widthPixels + " – " + dm.heightPixels);

第二種方式獲取DipalyMetrics對象（!= 上一種方式獲取的對象 ）
DisplayMetrics dm = activity.getResources().getDisplayMetrics();

Activity頁面切換效果:
new Handler().postDelayed(new Runnable() {
            @Override
            public void run()
            {
                Intent intent = new Intent(TransitionActivity.this, DeviceActivity.class);
                startActivity(intent);
                finish();
                //頁面切換 — 淡入淡出效果
                overridePendingTransition(android.R.anim.fade_in, android.R.anim.fade_out);
//                overridePendingTransition(R.anim.zoomin, R.anim.zoomout);
            }
        }, 5000);

摘自  我說_小莫