Android中的OnTabListener无法正常工作

Question

I have run into a problem where when I put the name of a fragment, an error occurs as shows:

Type mismatch: cannot convert from Fragment1 to Fragment

Here is my MainActivity.java code:

package com.example.currencyconverter;


import android.app.ActionBar;
import android.app.ActionBar.Tab;
import android.app.Activity;
import android.app.Fragment;
import android.app.FragmentTransaction;
import android.content.Intent;
import android.os.Bundle;
import android.os.StrictMode;
import android.view.Menu;
import android.view.MenuInflater;
import android.view.LayoutInflater;
import android.view.View;


public class MainActivity extends Activity implements OnClickListener {

@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);

ActionBar actionBar = getActionBar();
actionBar.setSubtitle("Created By Rohit Nandakumar");
actionBar.setTitle("Currency Converter"); 
actionBar.setNavigationMode(ActionBar.NAVIGATION_MODE_TABS);

ActionBar.Tab Frag1 = actionBar.newTab().setText("Converter");
ActionBar.Tab Frag2 = actionBar.newTab().setText("Currencies");

Fragment fragment1 = new Fragment1();
Fragment fragment2 = new Fragment2();

Frag1.setTabListener(new MyTabsListener(fragment1));
Frag2.setTabListener(new MyTabsListener(fragment2));

actionBar.addTab(Frag1);
actionBar.addTab(Frag2);
}

Here is my Fragment1 code:

package com.example.currencyconverter;

import android.app.Fragment;
import android.os.Bundle;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;

public class Fragment1 extends Fragment{
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
return inflater.inflate(R.layout.activity_main, container, false);
}
}

This is my Fragment 2 code:

package com.example.currencyconverter;

import android.app.Fragment;
import android.os.Bundle;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;

public class Fragment2 extends Fragment{
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
return inflater.inflate(R.layout.activity_first, container, false);
}
}

Here is the MyTabsListener.java file:

package com.example.currencyconverter;

import android.app.ActionBar.Tab;
import android.app.ActionBar.TabListener;
import android.app.ActionBar;
import android.app.Fragment;
import android.app.FragmentTransaction;

public class MyTabsListener implements TabListener {

public Fragment fragment;

public MyTabsListener(Fragment fragment) {
    this.fragment = fragment;
}

@Override
public void onTabReselected(Tab tab, FragmentTransaction ft) {
    // TODO Auto-generated method stub
}

@Override
public void onTabSelected(Tab tab, FragmentTransaction ft) {
    // TODO Auto-generated method stub
    ft.replace(R.id.fragment_container, fragment);

}

@Override
public void onTabUnselected(Tab tab, FragmentTransaction ft) {
    // TODO Auto-generated method stub

}

} The problem occurs right here in the MainActivity.java file:

Fragment fragment1 = new Fragment1();
Fragment fragment2 = new Fragment2();

The

new Fragment1();

and the

new Fragment2();

part of the code is highlighted and it says:

Type mismatch: cannot convert from Fragment1 to Fragment

What is happening? What am i doing wrong? Any help is greatly appreciated. I have already asked this question before, but I have gotten no answers that are correct. I have searched all over the internet trying to find the answer. Again, any help is greatly appreciated.

Answer 1

Instead of:

Fragment fragment1 = new Fragment1();
Fragment fragment2 = new Fragment2();

Try to do:

Fragment1 fragment1 = new Fragment1();
Fragment2 fragment2 = new Fragment2();

You need to create new objects of the Fragment classes that you have created( ie create objects of classes Fragment1 and Fragment2 not the objects of type Fragment . )

The way you are doing, you are creating the object of type Fragment but initializing it with the types Fragment1 and Fragment2 . That's why it is giving the error.

Hope this helps.