android片段無法在模擬器中打開

Question

首先，我是新的android和英語:)對不起。我遇到了Fragment經理的問題。我讀了一些在主要活動中使用片段的代碼。但是它不能在模擬器中運行，並且您可以在下面看到代碼。我認爲關於「導入android.support.v4.app.FragmentManager;」的問題線。我不知道也許我必須像這樣使用它「import android.app.FragmenManager」 我希望你能理解我的句子並幫助我。 謝謝。

package com.example.ilk.fragmenttransactions; 

import android.support.v4.app.FragmentActivity; 
import android.support.v4.app.FragmentManager; 
import android.support.v4.app.FragmentTransaction; 
import android.support.v7.app.ActionBarActivity; 
import android.os.Bundle; 
import android.view.Menu; 
import android.view.MenuItem; 
import android.view.View; 
import android.widget.Toast; 



public class MainActivity extends FragmentActivity { 

    FragmentManager fm; 

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

    public void addA(View v){ 
     FragmentA f1 = new FragmentA(); 
     FragmentTransaction transaction = fm.beginTransaction(); 
     transaction.add(R.id.fragment_container, f1, "A"); 
     transaction.commit(); 
    } 

    public void removeA(View v){ 
     FragmentA f1 = (FragmentA)fm.findFragmentByTag("A"); 
     FragmentTransaction transaction = fm.beginTransaction(); 
     if(f1 != null){ 
      transaction.remove(f1); 
      transaction.commit(); 
     } 
     else{ 
      Toast.makeText(this, "There is no A! you cannot delete it", Toast.LENGTH_LONG).show(); 
     } 
    } 

    public void addB(View v){ 
     FragmentB f2 = new FragmentB(); 
     FragmentTransaction transaction = fm.beginTransaction(); 
     transaction.add(R.id.fragment_container, f2, "B"); 
     transaction.commit(); 
    } 

    public void removeB(View v){ 
     FragmentB f2 = (FragmentB)fm.findFragmentByTag("B"); 
     FragmentTransaction transaction = fm.beginTransaction(); 
     if(f2 != null){ 
      transaction.remove(f2); 
      transaction.commit(); 
     } 
     else{ 
      Toast.makeText(this, " There is no B! you cannot delete it ",Toast.LENGTH_SHORT).show(); 
     } 
    } 


    @Override 
    public boolean onCreateOptionsMenu(Menu menu) { 
     // Inflate the menu; this adds items to the action bar if it is present. 
     getMenuInflater().inflate(R.menu.menu_main, menu); 
     return true; 
    } 

    @Override 
    public boolean onOptionsItemSelected(MenuItem item) { 
     // Handle action bar item clicks here. The action bar will 
     // automatically handle clicks on the Home/Up button, so long 
     // as you specify a parent activity in AndroidManifest.xml. 
     int id = item.getItemId(); 

     //noinspection SimplifiableIfStatement 
     if (id == R.id.action_settings) { 
      return true; 
     } 

     return super.onOptionsItemSelected(item); 
    } 
} 

Answer 1

使用import android.support.v4.app.FragmentManager。

片段不加載，因爲你沒有做，當你的應用程序初始化任何交易：我想你正試圖通過單擊佈局的元素與

加載片段

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

財產

例如：

<Button 
    android:id="@+id/myButton" 
    android:layout_width="wrap_content" 
    android:layout_height="wrap_content" 
    android:onClick="addA" /> 

執行這個方法：

public void addA(View v){ 
     FragmentA f1 = new FragmentA(); 
     FragmentTransaction transaction = fm.beginTransaction(); 
     transaction.add(R.id.fragment_container, f1, "A"); 
     transaction.commit(); 
    }