從GridView中更改項目

Question

我試圖訪問我的GridView中的TextView，並在我調用playSoE方法時更改它們的背景顏色，使其更改。

ImageAdapter.java：

public class ImageAdapter extends BaseAdapter { 
    private Context mContext; 
    private int mCount; 
    public int[] mIds; //stores Ids from TextViews 

    public ImageAdapter(Context c, int count) { 
     mContext = c; 
     mCount = count; 
     mIds = new int[mCount]; 
    } 

    public int getCount() { 
     return mCount; 
    } 

    public Object getItem(int position) { 
     return null; 
    } 

    public long getItemId(int position) { 
     return 0; 
    } 

    // create a new ImageView for each item referenced by the Adapter 
    public View getView(int position, View convertView, ViewGroup parent) { 
     TextView textView; 

     if (convertView == null) { 
      // if it's not recycled, initialize some attributes 
      textView = new TextView(mContext); 
      mIds[position] = textView.getId(); //Id is stored into array 
      textView.setGravity(Gravity.CENTER); 
      textView.setLayoutParams(new GridView.LayoutParams(100, 100)); 

     } else { 
      textView = (TextView) convertView; 
     } 

     textView.setBackgroundColor(Color.RED); 
     textView.setText("" + position); 
     return textView; 
    } 

} 

activity_main.xml中：

<?xml version="1.0" encoding="utf-8"?> 
<HorizontalScrollView xmlns:android="http://schemas.android.com/apk/res/android" 
    xmlns:tools="http://schemas.android.com/tools" 
    android:layout_width="match_parent" 
    android:layout_height="wrap_content" 
    android:scrollbars="none" 
    android:id="@+id/title_horizontalScrollView" 
    android:layout_margin="1dp" 
    android:fillViewport="false"> 

    <RelativeLayout 
     android:layout_width="match_parent" 
     android:layout_height="match_parent" 
     tools:context=".MainActivity" 
     android:id="@+id/relativelayout"> 

     <GridView 
      android:id="@+id/mGridView" 
      android:layout_width="match_parent" 
      android:layout_height="match_parent" 
      android:columnWidth="90dp" 
      android:verticalSpacing="10dp" 
      android:horizontalSpacing="10dp" 
      android:stretchMode="columnWidth" 
      android:gravity="center" 
     /> 

    </RelativeLayout> 

</HorizontalScrollView> 

MainActivity.java：

public class MainActivity extends ActionBarActivity { 

    private boolean mIsPlaying; 
    private int primesLE; 
    private GridView mGridView; 

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

     mIsPlaying = false; 

     ViewGroup.LayoutParams layoutParams; 

     primesLE = 225; 
     int numOfColumns = (int)Math.round(Math.sqrt((double) primesLE)); 
     int numOfRows = (int)Math.ceil((double)primesLE/(double)numOfColumns); 

     GridView mGridView = (GridView) findViewById(R.id.mGridView); 
     layoutParams = mGridView.getLayoutParams(); 
     layoutParams.width = 150*numOfColumns; //this is in pixels 
     mGridView.setLayoutParams(layoutParams); 
     mGridView.setNumColumns(numOfColumns); 
     mGridView.setAdapter(new ImageAdapter(this, primesLE)); 

    } 



    @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(); 
     Log.d("Menu","Button Pressed"); 
     //noinspection SimplifiableIfStatement 
     if (id == R.id.action_settings) { 
      return true; 
     } 

     else if (id == R.id.action_status){ 
      if(mIsPlaying) { 
       mIsPlaying = false; 
       item.setIcon(R.drawable.ic_action_play); 
       item.setTitle("Play"); 
       playSoE(); 
      } 
      else { 
       mIsPlaying = true; 
       item.setIcon(R.drawable.ic_action_pause); 
       item.setTitle("Pause"); 
      } 
      return true; 
     } 

     return super.onOptionsItemSelected(item); 
    } 

    private void playSoE(){ 
     int[] viewIds = ((ImageAdapter)mGridView.getAdapter()).mIds; //trying to get the Ids for the TextViews, doesn't work and crashes 
     for(int i = 0; i < primesLE;i++){ 
      Log.d("Getting view number",""+i); 
      mGridView.getAdapter(). 
       getItem(i).setBackgroundColor(Color.BLUE);//this doesn't work, crashes 
      mGridView.getChildAt(i).setBackgroundColor(Color.BLUE); //this doesn't work either, crashes 
     } 
    } 

} 

的AndroidManifest.xml：

<?xml version="1.0" encoding="utf-8"?> 
<manifest xmlns:android="http://schemas.android.com/apk/res/android" 
    package="com.myname.sieveoferatosthenes" > 

    <application 
     android:allowBackup="true" 
     android:icon="@drawable/ic_launcher" 
     android:label="@string/app_name" 
     android:theme="@style/AppTheme" > 
     <activity 
      android:name=".MainActivity" 
      android:label="@string/app_name" > 
      <intent-filter> 
       <action android:name="android.intent.action.MAIN" /> 

       <category android:name="android.intent.category.LAUNCHER" /> 
      </intent-filter> 
     </activity> 
    </application> 

</manifest> 

我一直在尋找方法來做到這一點，但他們似乎都沒有爲我工作。

Answer 1

我解決了我的問題，mGridView一直爲空。在MainActivity中，我使用的是GridView mGridView = (GridView) findViewById(R.id.mGridView);，它的編碼很糟糕，並沒有考慮到GridView嵌套在xml中。我把它改爲

View v1 = findViewById(R.id.title_horizontalScrollView); 
View v2 = v1.findViewById(R.id.relativelayout); 
mGridView = (GridView) v2.findViewById(R.id.mGridView); 

而且mGridView是不是空了，然後用getChildAt(int position)會得到我，我想(although some positions I still cannot access).

Answer 2

在你playSoE方法包括本

<defined textview name here>.setBackgroundColor(Color.parseColor("#<hexadecimal color of your choice>")); 

希望我幫助。

編輯：我個人比較喜歡W3找到十六進制顏色 http://www.w3schools.com/tags/ref_colorpicker.asp

應該包括哪些內容 在XML文件中

<TextView 
      android:layout_width="wrap_content" 
       android:layout_height="wrap_content" 
       android:id="@+id/whateveryouwantitsanid" 
       android:layout_weight="1" 
       /> 

的Java

private TextView Texter;... 
//in your on create 
Texter = (TextView) findViewById(R.id.whateveryouwantitsanid); 
//where you want to change background 
Texter.setBackgroundColor(Color.parseColor("#yourhexcolorhere")); 

PS我不知道爲什麼你」重新把你的ID放在數組中