Question

Viewpager无法正常显示错误。请帮我。我还有一个疑问，如何在同一个类中扩展Fragments和AppCompatActivity。我知道java不支持多继承，但有没有办法实现它？

import android.os.Bundle;
import android.support.v4.app.Fragment;
import android.support.v4.app.FragmentManager;
import android.support.v4.app.FragmentPagerAdapter;
import android.support.v4.view.ViewPager;
import android.support.v7.app.AppCompatActivity;
import android.view.View;
import android.widget.Button;
import android.widget.Toast;

import java.util.ArrayList;
import java.util.List;

public class MainActivity extends AppCompatActivity {

Button btn1;

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

    ViewPager viewPager;
    viewPager = findViewById(R.id.pager);
    ViewPagerAdapter adapter = new                 ViewPagerAdapter(getSupportFragmentManager());
    adapter.addFragment(new FragmentOne(), "FRAG1");
    adapter.addFragment(new FragmentTwo(), "FRAG2");
    adapter.addFragment(new FragmentThree(), "FRAG3");
    viewPager.setAdapter(adapter);
    btn1 = findViewById(R.id.btn1);
    btn1.setOnClickListener((View.OnClickListener) MainActivity.this);



    btn1.setOnClickListener(new View.OnClickListener() {
        @Override
      public void onClick(View v) {
            Toast.makeText(getApplicationContext(),"Fragment One", Toast.LENGTH_SHORT).show();
        }




    };



class ViewPagerAdapter extends FragmentPagerAdapter {
    private final List<Fragment> mFragmentList = new ArrayList<>();
    private final List<String> mFragmentTitleList = new ArrayList<>();

    public ViewPagerAdapter(FragmentManager manager) {
        super(manager);
    }

    @Override
    public Fragment getItem(int position) {
        return mFragmentList.get(position);
    }

    @Override
    public int getCount() {
        return mFragmentList.size();
    }

    public void addFragment(Fragment fragment, String title) {
        mFragmentList.add(fragment);
        mFragmentTitleList.add(title);
    }

    @Override
    public CharSequence getPageTitle(int position) {
        return mFragmentTitleList.get(position);
    }
    }
}

片段1，片段2和片段3的代码类似于代码：

import android.os.Bundle;
import android.support.v4.app.Fragment;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;



public class FragmentOne extends Fragment {

public FragmentOne() {

}

@Override
public void onCreate(Bundle savedInstanceState) {

    super.onCreate(savedInstanceState);
}

@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
                         Bundle savedInstanceState) {



    return inflater.inflate(R.layout.fragment_one, container, false);
}

}

如何继承Fragment和AppCompatActivity？

0 个答案: