java - 如何更改 Android Activity 的背景颜色

Question

我想使用 AlertDialog 更改 Activity 的背景颜色。这是我所做的:

private SharedPreferences prefs;    
private static final String SELECTED_ITEM = "SelectedItem"; 
private Editor sharedPrefEditor;

btnchangeColor = (ImageButton) findViewById(R.id.btnchangeColor);
btnchangeColor.setOnClickListener(new View.OnClickListener() {

    @Override
    public void onClick(View v) {

        final CharSequence[] items={"Red","Green","Blue", "Yellow", "#EE82EE"};

        AlertDialog.Builder builder = new AlertDialog.Builder(
                ContentView_2.this);

        builder.setTitle("Pick a Color");
        builder.setPositiveButton("ok", new DialogInterface.OnClickListener() { 

            @Override
            public void onClick(DialogInterface dialog, int which) {}
        });

        builder.setSingleChoiceItems(items, getSelectedItem(), new DialogInterface.OnClickListener() {

            @Override
            public void onClick(DialogInterface dialog, int which) {
                // TODO Auto-generated method stub
                wvContent = (WebView) findViewById(R.id.wvContent);
                //LinearLayout ll=(LinearLayout)findViewById(R.id.wvContent); 

                if("Red".equals(items[which]))
                {
                    wvContent.setBackgroundColor(Color.RED);
                }
                else if("Green".equals(items[which]))
                {
                    wvContent.setBackgroundColor(Color.GREEN);
                    }
                else if("Blue".equals(items[which]))
                {
                    wvContent.setBackgroundColor(Color.BLUE);
                    }
                else if("Yellow".equals(items[which]))
                {
                    wvContent.setBackgroundColor(Color.YELLOW);
                    }
                else if("#EE82EE".equals(items[which]))
                {
                    wvContent.setBackgroundColor(Color.rgb(184,184,184));
                    }
                saveSelectedItem(which);
            }
        });
        builder.show();

    }});
    }

private int getSelectedItem() {
    if (prefs == null) {
        prefs = PreferenceManager
                .getDefaultSharedPreferences(this);
    }
    return prefs.getInt(SELECTED_ITEM, -1);
}

private void saveSelectedItem(int which) {
    if (prefs == null) {
        prefs = PreferenceManager
                .getDefaultSharedPreferences(this);
    }
    sharedPrefEditor = prefs.edit();
    sharedPrefEditor.putInt(SELECTED_ITEM, which);
    sharedPrefEditor.commit();
}

我还将此代码添加到 OnCreate 中:

wvContent = (WebView) findViewById(R.id.wvContent); 
    wvContent.setBackgroundColor(getSelectedItem());

颜色已选择，并且 Web View (wvContent) 更改为所选颜色，但这不会保存到共享首选项和/或从共享首选项加载。当 Activity 重新启动时，它会返回到默认颜色。

所以问题是:如何正确地将所选颜色保存到 SharedPreferences 并在 Activity 重新启动时加载它？

非常感谢您的帮助。

Answer 1

目前，您正在 SharedPreferences 中保存所选项目的位置而不是颜色代码。这样做:

wvContent = (WebView) findViewById(R.id.wvContent);
int bg_color=Color.TRANSPARENT;
 if("Red".equals(items[which]))
   {
       wvContent.setBackgroundColor(Color.RED);
       bg_color=Color.RED;
   }
 else if("Green".equals(items[which]))
  {
      wvContent.setBackgroundColor(Color.GREEN);
       bg_color=Color.GREEN;
  }
........
// save color in SharedPreferences
 saveSelectedItem(bg_color);

现在 getSelectedItem() 方法返回先前从微调器中选择的值的颜色代码。