Java 调用getSupportFragmentManager()
在两个不同的事件中,我将变量从MainActivity传递到HomeFragment,如下所示:Java 调用getSupportFragmentManager(),java,android,database,image,android-fragments,Java,Android,Database,Image,Android Fragments,在两个不同的事件中,我将变量从MainActivity传递到HomeFragment,如下所示: public void buttonCreator(Drawable d,String a) { int fragsize = getSupportFragmentManager().getFragments().size(); Log.d("tag_name", "Size of Home Fragment" + fragsize); HomeFragment homeFr
public void buttonCreator(Drawable d,String a) {
int fragsize = getSupportFragmentManager().getFragments().size();
Log.d("tag_name", "Size of Home Fragment" + fragsize);
HomeFragment homeFragment = (HomeFragment)getSupportFragmentManager().getFragments().get(1);
homeFragment.createButton(d, a);
}
首先,我在MainActivity中调用此方法:
buttonCreator(d, Name);
然后我将变量“d”和“Name”发送到HomeFragment,如下所示:
public void buttonCreator(Drawable d,String a) {
int fragsize = getSupportFragmentManager().getFragments().size();
Log.d("tag_name", "Size of Home Fragment" + fragsize);
HomeFragment homeFragment = (HomeFragment)getSupportFragmentManager().getFragments().get(1);
homeFragment.createButton(d, a);
}
第一次调用buttonCreator(d,Name)时,我没有收到任何错误第二次尝试通过buttonCreator将变量传递给HomeFragment时,出现错误“IndexOutOfBoundsException:无效索引1,大小为1”。我认为这与HomeFragment的数组大小有关,但我不完全理解此处片段和数组之间的关系
我知道第一次尝试访问HomeFragment时,我调用:
int fragsize = getSupportFragmentManager().getFragments().size();
我得到的输出是“3”,第二次调用它时(当它崩溃时),我得到的输出是“1”有人能解释一下为什么会发生这种情况,以及我如何解决这个问题吗?
这是我的全部主要活动,如果有帮助的话。我第一次调用buttonCreator是在“RepeaterTask”中,第二次(当它崩溃时)是通过onCreate(),通过“else”语句
public class MainActivity extends FragmentActivity implements HomeFragment.ButtonCreator {
private Thread repeatTaskThread;
private byte[] byteArray;
private static Context mContext;
private Cursor c;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
mContext = getApplicationContext();
DatabaseStructure database = new DatabaseStructure(mContext);
database.checkDatabase();
// if database is empty (checkDatabase == false) Open empty HomeFragment
if (!database.checkDatabase()) {
Log.d("tag_name", "Database is Empty: Open HomeFragment");
FragmentTransaction ft = getSupportFragmentManager().beginTransaction();
ft.replace(R.id.container, new HomeFragment(),"Home_Fragment")
.addToBackStack("Home_Fragment").commit();
}
else {
DatabaseStructure appDatabase = new DatabaseStructure(this);
c = appDatabase.getApps();
c.moveToFirst();
String Name = c.getString(0);
Log.d("tag_name", "String from Database" + appName);
byte[] image = c.getBlob(1);
Log.d("tag_name", "Image from Database" + image);
Bitmap bitmap = BitmapFactory.decodeByteArray(image, 0, image.length);
Drawable d = new BitmapDrawable(Resources.getSystem(), bitmap);
Log.d("tag_name", "Drawable from Database" + d);
buttonCreator(d, Name);
}
RepeatTask();
}
public void buttonCreator(Drawable d,String a) {
int fragsize = getSupportFragmentManager().getFragments().size();
Log.d("tag_name", "Size of Home Fragment" + fragsize);
HomeFragment homeFragment = (HomeFragment)getSupportFragmentManager().getFragments().get(1);
homeFragment.createButton(d, a);
}
public void RepeatTask() {
repeatTaskThread = new Thread() {
public void run() {
while (true) {
try {
Socket socket = new Socket("192.168.0.26", 5050);
// Get data sent through socket
DataInputStream DIS = new DataInputStream(socket.getInputStream());
System.out.println("DataInputStream Started");
final String Name = DIS.readUTF();
int len = DIS.readInt();
final byte[] data = new byte[len];
DIS.readFully(data, 0, data.length);
Bitmap bitmap = BitmapFactory.decodeByteArray(data, 0, data.length);
final Drawable d = new BitmapDrawable(getResources(), Bitmap.createScaledBitmap(bitmap, 90, 90, true));
runOnUiThread(new Runnable() {
@Override
public void run() {
buttonCreator(d, Name);
DatabaseStructure database = new DatabaseStructure(mContext);
database.addEntry(Name, data);
}
});
socket.close();
} catch (Exception e) {
System.out.println("Exception is " + e.toString());
}
try {
// Sleep for 5 seconds
Thread.sleep(5000);
} catch (Exception e) {
e.printStackTrace();
}
}
}
;
};
repeatTaskThread.start();
}
}
数组和列表的索引是从零开始的(第一个索引是0而不是1),所以请尝试
如果我这样做,我的应用程序在您想要获取另一个片段时崩溃,并出现错误“无法启动活动”,通常不应尝试在列表中查找它。如果您已经设置了id()或标记(),请按id()或标记()查找。@zapl当我这样做时:“HomeFragment hm=(HomeFragment)getSupportFragmentManager().findFragmentByTag(“Home_Fragment”);Log.d(“tag_name”,“HomeFragment”+hm);hm.createButton(d,appName);“我得到hm=null:(试图解决这个问题。