Android Studio 2.1链接片段

Question

//Main activity.java
package com.example.sahilnitish.easyyagriculture;
import android.app.Activity;
import android.app.FragmentManager;
import android.app.FragmentTransaction;
import android.support.v4.app.Fragment;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
public class MainActivity extends Activity
{
 boolean status=false;
    Button bn;
    @Override
    protected void onCreate(Bundle savedInstanceState) 
{    
super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        bn=(Button)findViewById(R.id.bn);
        bn.setOnClickListener(new View.OnClickListener() 
{
            @Override
            public void onClick(View v)
            {
                FragmentManager fragmentManager = getFragmentManager();
                FragmentTransaction fragmentTransaction = fragmentManager.beginTransaction();
                if(!status)
                {
                    Fragmentone f1 =new Fragmentone();
                    fragmentTransaction.add(R.id.fragment_container,f1);
                    fragmentTransaction.commit();
                    bn.setText("Load Second fragment");
                    status=true;
                }
                else
                {
                    FragmentTwo f2 = new FragmentTwo();
                    fragmentTransaction.add(R.id.fragment_container,f2);
                    fragmentTransaction.commit();
                    bn.setText("Load first fragment");
                    status=false;
                }
            }
        });
    }
}

错误:-

Error:(29,40) Error: no suitable method for add(int,Fragmentone)方法FragmentTransaction.add(Fragment,String)不适用(参数不匹配;int不能转换为Fragment)方法FragmentTransaction.add(int,Fragment)不适用(参数不匹配;Fragmentone不能转换为Fragment)

fragmentone.java

package com.example.sahilnitish.easyyagriculture;
import android.os.Bundle;
import android.support.v4.app.Fragment;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
/**
 * A simple {@link Fragment} subclass.
 */
public class Fragmentone extends Fragment 
{
    public Fragmentone() 
    // Required empty public constructor
    }
    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
                             Bundle savedInstanceState) 
{
        // Inflate the layout for this fragment
        return inflater.inflate(R.layout.fragment_one_layout, container, false);
    }
}

Answer 1

您正在使用带有支持片段的FragmentManager。

要么让你的MainActivity扩展ActivityCompat并使用supportFragmentManager，要么让你的Fragment扩展一个"正常"的Fragment。

//Main activity.java
package com.example.sahilnitish.easyyagriculture;
import android.support.v7.app.AppCompatActivity;
import android.support.v4.app.FragmentTransaction;
import android.support.v4.app.Fragment;
import android.support.v4.app.FragmentManager;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
public class MainActivity extends AppCompatActivity
{
    boolean status=false;
    Button bn;
    @Override
    protected void onCreate(Bundle savedInstanceState) 
    {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        bn=(Button)findViewById(R.id.bn);
        bn.setOnClickListener(new View.OnClickListener() 
        {
            @Override
            public void onClick(View v)
            {
                FragmentManager fragmentManager = getSupportFragmentManager();
                FragmentTransaction fragmentTransaction = fragmentManager.beginTransaction();
                if(!status)
                {
                    Fragmentone f1 =new Fragmentone();
                    fragmentTransaction.add(R.id.fragment_container,f1);
                    fragmentTransaction.commit();
                    bn.setText("Load Second fragment");
                    status=true;
                }
                else
                {
                    FragmentTwo f2 = new FragmentTwo();
                    fragmentTransaction.add(R.id.fragment_container,f2);
                    fragmentTransaction.commit();
                    bn.setText("Load first fragment");
                    status=false;
                }
            }
        });
    }
}

Answer 2

这是因为你使用了错误的FragmentManager。

因此，首先将import语句从 更改为:

import android.app.FragmentManager;

:

import android.support.v4.app.FragmentManager;

，你也应该使用getSupportFragmentManager()。

so change:

FragmentManager fragmentManager = getFragmentManager();

:

FragmentManager fragmentManager = getSupportFragmentManager();

您的Activity class在您的情况下是MainActivity，应该扩展AppCompatActivity而不是Activity。