安卓有時用到的小功能

文獻種類：專題技術總結文獻；
開發工具與關鍵技術：
作者：彭浩達 ；年級： 2017 ；撰寫時間： 2020 年 5 月 18 日
安卓有時用到的小功能
Dao部分
1.Android根據包名打開應用：
public void startAPP(String appPackageName){
try{
Intent intent = this.getPackageManager().getLaunchIntentForPackage(appPackageName);
startActivity(intent);

}catch(Exception e){
Toast.makeText(this, “沒有安裝”, Toast.LENGTH_LONG).show();
}

}

2.監聽ListView滑動到底部：
listview.setOnScrollListener(new OnScrollListener(){
@Override
public void onScrollStateChanged(AbsListView view, int scrollState){
// 當不滾動時
if (scrollState == OnScrollListener.SCROLL_STATE_IDLE) {
// 判斷是否滾動到底部
if (view.getLastVisiblePosition() == view.getCount() - 1) {
//加載更多功能的代碼
}
}

}  

});

3.Android根據包名判斷是否安裝某個應用：
public static boolean checkApkExist(Context context, String packageName) {
if (packageName == null || “”.equals(packageName))
return false; try
{
ApplicationInfo info = context.getPackageManager()
.getApplicationInfo(packageName,

   PackageManager.GET_UNINSTALLED_PACKAGES);

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return true;

} catch (NameNotFoundException e) {
return false;
}

}

4.獲取隨機字符串
定義字符數組
private static char[] chars = new char[]{‘A’, ‘B’, ‘C’, ‘D’, ‘E’, ‘F’, ‘G’, ‘H’, ‘I’, ‘J’, ‘K’, ‘L’, ‘M’, ‘N’,‘O’,‘P’, ‘Q’, ‘R’, ‘S’, ‘T’, ‘U’, ‘V’, ‘W’, ‘X’, ‘Y’, ‘Z’};
//獲取隨機字符串
public static String getRandomString() {
Random random = new Random();
//獲取隨機長度
int length = random.nextInt(chars.length) + 1;
char[] data = new char[length];

    for (int i = 0; i < length; i++) {
        //獲取隨機字符
        int index = random.nextInt(chars.length);
        data[i] = chars[index];
    }
    return new String(data);
}

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