Issues with Android Tabhost Example

Getting error in using TabHost

Your activity should extend TabActivity not Activity.

public class irctcdemo extends TabActivity {

and just use

tabHost = getTabHost();

remove this

tabHost = (TabHost)findViewById(android.R.id.tabhost);

and your Id should be android:id="@android:id/tabhost" for TabHost and
android:id="@android:id/tabs" for TabWidget

Issue with displaying TabHost Layout in new Intent

I have previously constructed tabhosts with an id of android:id="@+id/tabhost". Does this work for you?

You could also consider constructing your tab view programmatically:

    TabHost t = getTabHost();
TabSpec tab = t.newTabSpec(label)
.setIndicator(label, icon)
.setContent(intent);
t.addTab(tab);

Android FragmentTabHost - Not fully baked yet?

I finally got to the bottom of this. There is an issue with FragmentTabHost.java which will always create a TabHost element for you, no matter what you define in XML and inflate beforehand.

As such, I commented out that part of code when writing my own version of FragmentTabHost.java.

Make sure to use your new version of this in your XML layout, <com.example.app.MyFragmentTabHost

And of course inflate it:

Fragment1.java:

mTabHost = (MyFragmentTabHost) view.findViewById(android.R.id.tabhost);
mTabHost.setup(getActivity(), getChildFragmentManager(), android.R.id.tabcontent);

MyFragmentTabHost.java:

package com.example.app;

import java.util.ArrayList;

import android.content.Context;
import android.content.res.TypedArray;
import android.os.Bundle;
import android.os.Parcel;
import android.os.Parcelable;
import android.support.v4.app.Fragment;
import android.support.v4.app.FragmentManager;
import android.support.v4.app.FragmentTransaction;
import android.util.AttributeSet;
import android.view.View;
import android.widget.FrameLayout;
import android.widget.TabHost;

/**
* Special TabHost that allows the use of {@link Fragment} objects for
* its tab content. When placing this in a view hierarchy, after inflating
* the hierarchy you must call {@link #setup(Context, FragmentManager, int)}
* to complete the initialization of the tab host.
*
*/
public class MyFragmentTabHost extends TabHost
implements TabHost.OnTabChangeListener {
private final ArrayList<TabInfo> mTabs = new ArrayList<TabInfo>();
private FrameLayout mRealTabContent;
private Context mContext;
private FragmentManager mFragmentManager;
private int mContainerId;
private TabHost.OnTabChangeListener mOnTabChangeListener;
private TabInfo mLastTab;
private boolean mAttached;

static final class TabInfo {
private final String tag;
private final Class<?> clss;
private final Bundle args;
private Fragment fragment;

TabInfo(String _tag, Class<?> _class, Bundle _args) {
tag = _tag;
clss = _class;
args = _args;
}
}

static class DummyTabFactory implements TabHost.TabContentFactory {
private final Context mContext;

public DummyTabFactory(Context context) {
mContext = context;
}

@Override
public View createTabContent(String tag) {
View v = new View(mContext);
v.setMinimumWidth(0);
v.setMinimumHeight(0);
return v;
}
}

static class SavedState extends BaseSavedState {
String curTab;

SavedState(Parcelable superState) {
super(superState);
}

private SavedState(Parcel in) {
super(in);
curTab = in.readString();
}

@Override
public void writeToParcel(Parcel out, int flags) {
super.writeToParcel(out, flags);
out.writeString(curTab);
}

@Override
public String toString() {
return "FragmentTabHost.SavedState{"
+ Integer.toHexString(System.identityHashCode(this))
+ " curTab=" + curTab + "}";
}

public static final Parcelable.Creator<SavedState> CREATOR
= new Parcelable.Creator<SavedState>() {
public SavedState createFromParcel(Parcel in) {
return new SavedState(in);
}

public SavedState[] newArray(int size) {
return new SavedState[size];
}
};
}

public MyFragmentTabHost(Context context) {
// Note that we call through to the version that takes an AttributeSet,
// because the simple Context construct can result in a broken object!
super(context, null);
initFragmentTabHost(context, null);
}

public MyFragmentTabHost(Context context, AttributeSet attrs) {
super(context, attrs);
initFragmentTabHost(context, attrs);
}

private void initFragmentTabHost(Context context, AttributeSet attrs) {
TypedArray a = context.obtainStyledAttributes(attrs,
new int[] { android.R.attr.inflatedId }, 0, 0);
mContainerId = a.getResourceId(0, 0);
a.recycle();

super.setOnTabChangedListener(this);

/*** REMOVE THE REST OF THIS FUNCTION ***/
/*** findViewById(android.R.id.tabs) IS NULL EVERY TIME ***/
}

/**
* @deprecated Don't call the original TabHost setup, you must instead
* call {@link #setup(Context, FragmentManager)} or
* {@link #setup(Context, FragmentManager, int)}.
*/
@Override @Deprecated
public void setup() {
throw new IllegalStateException(
"Must call setup() that takes a Context and FragmentManager");
}

public void setup(Context context, FragmentManager manager) {
super.setup();
mContext = context;
mFragmentManager = manager;
ensureContent();
}

public void setup(Context context, FragmentManager manager, int containerId) {
super.setup();
mContext = context;
mFragmentManager = manager;
mContainerId = containerId;
ensureContent();
mRealTabContent.setId(containerId);

// We must have an ID to be able to save/restore our state. If
// the owner hasn't set one at this point, we will set it ourself.
if (getId() == View.NO_ID) {
setId(android.R.id.tabhost);
}
}

private void ensureContent() {
if (mRealTabContent == null) {
mRealTabContent = (FrameLayout)findViewById(mContainerId);
if (mRealTabContent == null) {
throw new IllegalStateException(
"No tab content FrameLayout found for id " + mContainerId);
}
}
}

@Override
public void setOnTabChangedListener(OnTabChangeListener l) {
mOnTabChangeListener = l;
}

public void addTab(TabHost.TabSpec tabSpec, Class<?> clss, Bundle args) {
tabSpec.setContent(new DummyTabFactory(mContext));
String tag = tabSpec.getTag();

TabInfo info = new TabInfo(tag, clss, args);

if (mAttached) {
// If we are already attached to the window, then check to make
// sure this tab's fragment is inactive if it exists. This shouldn't
// normally happen.
info.fragment = mFragmentManager.findFragmentByTag(tag);
if (info.fragment != null && !info.fragment.isDetached()) {
FragmentTransaction ft = mFragmentManager.beginTransaction();
ft.detach(info.fragment);
ft.commit();
}
}

mTabs.add(info);
addTab(tabSpec);
}

@Override
protected void onAttachedToWindow() {
super.onAttachedToWindow();

String currentTab = getCurrentTabTag();

// Go through all tabs and make sure their fragments match
// the correct state.
FragmentTransaction ft = null;
for (int i=0; i<mTabs.size(); i++) {
TabInfo tab = mTabs.get(i);
tab.fragment = mFragmentManager.findFragmentByTag(tab.tag);
if (tab.fragment != null && !tab.fragment.isDetached()) {
if (tab.tag.equals(currentTab)) {
// The fragment for this tab is already there and
// active, and it is what we really want to have
// as the current tab. Nothing to do.
mLastTab = tab;
} else {
// This fragment was restored in the active state,
// but is not the current tab. Deactivate it.
if (ft == null) {
ft = mFragmentManager.beginTransaction();
}
ft.detach(tab.fragment);
}
}
}

// We are now ready to go. Make sure we are switched to the
// correct tab.
mAttached = true;
ft = doTabChanged(currentTab, ft);
if (ft != null) {
ft.commit();
mFragmentManager.executePendingTransactions();
}
}

@Override
protected void onDetachedFromWindow() {
super.onDetachedFromWindow();
mAttached = false;
}

@Override
protected Parcelable onSaveInstanceState() {
Parcelable superState = super.onSaveInstanceState();
SavedState ss = new SavedState(superState);
ss.curTab = getCurrentTabTag();
return ss;
}

@Override
protected void onRestoreInstanceState(Parcelable state) {
SavedState ss = (SavedState)state;
super.onRestoreInstanceState(ss.getSuperState());
setCurrentTabByTag(ss.curTab);
}

@Override
public void onTabChanged(String tabId) {
if (mAttached) {
FragmentTransaction ft = doTabChanged(tabId, null);
if (ft != null) {
ft.commit();
}
}
if (mOnTabChangeListener != null) {
mOnTabChangeListener.onTabChanged(tabId);
}
}

private FragmentTransaction doTabChanged(String tabId, FragmentTransaction ft) {
TabInfo newTab = null;
for (int i=0; i<mTabs.size(); i++) {
TabInfo tab = mTabs.get(i);
if (tab.tag.equals(tabId)) {
newTab = tab;
}
}
if (newTab == null) {
throw new IllegalStateException("No tab known for tag " + tabId);
}
if (mLastTab != newTab) {
if (ft == null) {
ft = mFragmentManager.beginTransaction();
}
if (mLastTab != null) {
if (mLastTab.fragment != null) {
ft.detach(mLastTab.fragment);
}
}
if (newTab != null) {
if (newTab.fragment == null) {
newTab.fragment = Fragment.instantiate(mContext,
newTab.clss.getName(), newTab.args);
ft.add(mContainerId, newTab.fragment, newTab.tag);
} else {
ft.attach(newTab.fragment);
}
}

mLastTab = newTab;
}
return ft;
}
}

Android - TabHost / TabWidget

As you mentioned you should extend from ActivityGroup , but if you don't want a deprecated Class so you can Use Fragments and FragmentManager : Fragments

android TabHost inside a LinearLayout

Problem solved.
The correct solution, as given by the user 207 in one of the comments, from another stackoverflow question is this:

This is the XML:

<?xml version="1.0" encoding="utf-8"?>

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="vertical" android:layout_width="fill_parent"
android:layout_height="fill_parent">
<TabHost android:id="@android:id/tabhost"
android:layout_width="fill_parent" android:layout_height="fill_parent">
<LinearLayout android:orientation="vertical"
android:layout_width="fill_parent" android:layout_height="fill_parent"
android:padding="5dp">
<TabWidget android:id="@android:id/tabs"
android:layout_width="fill_parent" android:layout_height="53px"
android:tabStripEnabled="false" android:layout_margin="1px"
android:background="#222222" />
<FrameLayout android:id="@android:id/tabcontent"
android:layout_width="fill_parent" android:layout_height="fill_parent"
android:padding="5dp" />
</LinearLayout>
</TabHost>
</LinearLayout>

and java file:

package eu.pkg.tabsExample;

import android.app.Activity;
import android.app.LocalActivityManager;
import android.content.Intent;
import android.content.res.Resources;
import android.os.Bundle;
import android.os.Handler;
import android.widget.TabHost;

public class TabsExampleActivity extends Activity {

TabHost tabHost;
LocalActivityManager mLocalActivityManager;

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

initTabs(savedInstanceState);
}

@Override
protected void onResume() {
mLocalActivityManager.dispatchResume();
super.onResume();
}

@Override
protected void onPause() {
mLocalActivityManager.dispatchPause(isFinishing());
super.onPause();
}

private void initTabs(Bundle savedInstanceState) {
Resources res = getResources(); // Resource object to get Drawables
tabHost = (TabHost) findViewById(android.R.id.tabhost); // The activity TabHost
mLocalActivityManager = new LocalActivityManager(this, false);
mLocalActivityManager.dispatchCreate(savedInstanceState);
tabHost.setup(mLocalActivityManager);

TabHost.TabSpec spec; // Resusable TabSpec for each tab
Intent intent; // Reusable Intent for each tab

intent = new Intent("eu.pkg.tabsExample.BuildingTabActivity");
spec = tabHost.newTabSpec("text").setIndicator("",
res.getDrawable(R.drawable.tab_text_selector))
.setContent(intent);
tabHost.addTab(spec);

intent = new Intent().setClass(this, ClipArtTabActivity.class);
spec = tabHost.newTabSpec("clipart").setIndicator("",
res.getDrawable(R.drawable.tab_clipart_selector))
.setContent(intent);
tabHost.addTab(spec);

intent = new Intent().setClass(this, FrameSelectorTabActivity.class);
spec = tabHost.newTabSpec("frame").setIndicator("",
res.getDrawable(R.drawable.tab_frame_selector))
.setContent(intent);
tabHost.addTab(spec);

intent = new Intent().setClass(this, BgSelectorTabActivity.class);
spec = tabHost.newTabSpec("bg").setIndicator("",
res.getDrawable(R.drawable.tab_bg_selector))
.setContent(intent);
tabHost.addTab(spec);

intent = new Intent().setClass(this, BuildingTabActivity.class);
spec = tabHost.newTabSpec("build").setIndicator("",
res.getDrawable(R.drawable.tab_build_selector))
.setContent(intent);
tabHost.addTab(spec);

tabHost.setCurrentTab(4);
}
}

the magic behind the scene is in those 4 lines of code:

    tabHost = (TabHost) findViewById(android.R.id.tabhost);     // The activity TabHost
mLocalActivityManager = new LocalActivityManager(this, false);
mLocalActivityManager.dispatchCreate(savedInstanceState);
tabHost.setup(mLocalActivityManager);

Thank you all for contribution to this answer.



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