如果您不知道主要活动，那么可以使用包名来启动应用程序。

Intent launchIntent = getPackageManager().getLaunchIntentForPackage("com.package.address");
if (launchIntent != null) { 
    startActivity(launchIntent);//null pointer check in case package name was not found
}

启动新活动的步骤如下:

1.获取包的意图

2.如果意图为空重定向用户到播放商店

3.如果意图不为空，打开活动

public void launchNewActivity(Context context, String packageName) {
    Intent intent = null;
    if (android.os.Build.VERSION.SDK_INT >= android.os.Build.VERSION_CODES.CUPCAKE) {
        intent = context.getPackageManager().getLaunchIntentForPackage(packageName);
    }
    if (intent == null) {
        try {
            intent = new Intent(Intent.ACTION_VIEW);
            intent.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
            intent.setData(Uri.parse("market://details?id=" + packageName));
            context.startActivity(intent);
        } catch (android.content.ActivityNotFoundException anfe) {
            startActivity(new Intent(Intent.ACTION_VIEW, Uri.parse("https://play.google.com/store/apps/details?id=" + packageName)));
        }
    } else {
        intent.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
        context.startActivity(intent);
    }
}

我找到了解决办法。在应用程序的清单文件中，我找到了包的名称:com.package.address和我想启动的主活动的名称:MainActivity 下面的代码启动这个应用程序:

Intent intent = new Intent(Intent.ACTION_MAIN);
intent.setComponent(new ComponentName("com.package.address","com.package.address.MainActivity"));
startActivity(intent);

根据评论进行编辑

在某些版本中(如注释中建议的那样)，抛出的异常可能不同。

因此，下面的解决方案稍作修改

Intent launchIntent = null;
try{
   launchIntent = getPackageManager().getLaunchIntentForPackage("applicationId");
} catch (Exception ignored) {}

if(launchIntent == null){
    startActivity(new Intent(Intent.ACTION_VIEW).setData(Uri.parse("https://play.google.com/store/apps/details?id=" + "applicationId")));
} else {
    startActivity(launchIntent);
}

原来的答案

虽然回答得很好，有一个相当简单的实现来处理如果应用程序没有安装。我这样做

try{
    startActivity(getPackageManager().getLaunchIntentForPackage("applicationId"));
} catch (PackageManager.NameNotFoundException e) {
    startActivity(new Intent(Intent.ACTION_VIEW).setData(Uri.parse("https://play.google.com/store/apps/details?id=" + "applicationId")));
}

将“applicationId”替换为要打开的包，如com.google。地图等。

在Kotlin

fun openApplicationOrMarket(packageName: String) {
        var intent = requireContext().packageManager.getLaunchIntentForPackage(packageName)
        if (intent == null) {
            intent = Intent(Intent.ACTION_VIEW)
            intent.data = Uri.parse("market://details?id=$packageName")
        }

        intent.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK)
        requireContext().startActivity(intent)
    }

我知道这个问题已经得到了回答，但以下是我如何实现类似的东西:

Intent intent = getPackageManager().getLaunchIntentForPackage("com.package.name");
if (intent != null) {
    // We found the activity now start the activity
    intent.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
    startActivity(intent);
} else {
    // Bring user to the market or let them choose an app?
    intent = new Intent(Intent.ACTION_VIEW);
    intent.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
    intent.setData(Uri.parse("market://details?id=" + "com.package.name"));
    startActivity(intent);
}

更好的方法是:

public void startNewActivity(Context context, String packageName) {
    Intent intent = context.getPackageManager().getLaunchIntentForPackage(packageName);
    if (intent != null) {
        // We found the activity now start the activity
        intent.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
        context.startActivity(intent);
    } else {
        // Bring user to the market or let them choose an app?
        intent = new Intent(Intent.ACTION_VIEW);
        intent.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
        intent.setData(Uri.parse("market://details?id=" + packageName));
        context.startActivity(intent);
    }
}

删除重复代码:

public void startNewActivity(Context context, String packageName) {
    Intent intent = context.getPackageManager().getLaunchIntentForPackage(packageName);
    if (intent == null) {
        // Bring user to the market or let them choose an app?
        intent = new Intent(Intent.ACTION_VIEW);
        intent.setData(Uri.parse("market://details?id=" + packageName));
    }
    intent.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
    context.startActivity(intent);
}