Android - Context中的getText(int resId)方法和getString(int resId)方法的區別

Android開發中，經常在Activity中使用getText(int resId)和getString(int resId)這兩個方法，那么這兩個方法有什么區別和聯系呢？

這兩個方法的參數都是資源ID，區別在於getText(int resId)返回的是一個CharSequence，而getString(int resId)返回的是一個String。源代碼如下：

getText(int resId)：

 /**
  * Return a localized, styled CharSequence from the application's package's
  * default string table.
  *
  * @param resId Resource id for the CharSequence text
  */
 public final CharSequence getText(int resId) {
     return getResources().getText(resId);
 }

 

getString(int resId)：

/**
  * Return a localized string from the application's package's
  * default string table.
  *
  * @param resId Resource id for the string
  */
 public final String getString(int resId) {
     return getResources().getString(resId);
 }

 

可以看到，他們在各自的內部又調用了Resources類的getText(int id)和getString(int id)方法，那么我們就再看一下Resources類中的這兩個方法是怎么寫的:

Resources類中的getText(int id)：

 /**
   * Return the string value associated with a particular resource ID.  The
   * returned object will be a String if this is a plain string; it will be
   * some other type of CharSequence if it is styled.
   * {@more}
   *
   * @param id The desired resource identifier, as generated by the aapt
   *           tool. This integer encodes the package, type, and resource
   *           entry. The value 0 is an invalid identifier.
   *
   * @throws NotFoundException Throws NotFoundException if the given ID does not exist.
   *
   * @return CharSequence The string data associated with the resource, plus
   *         possibly styled text information.
   */
  public CharSequence getText(int id) throws NotFoundException {
      CharSequence res = mAssets.getResourceText(id);
      if (res != null) {
          return res;
      }
      throw new NotFoundException("String resource ID #0x"
                                  + Integer.toHexString(id));
  }

 

Resources類中的getString(int id)：

/**
   * Return the string value associated with a particular resource ID.  It
   * will be stripped of any styled text information.
   * {@more}
   *
   * @param id The desired resource identifier, as generated by the aapt
   *           tool. This integer encodes the package, type, and resource
   *           entry. The value 0 is an invalid identifier.
   *
   * @throws NotFoundException Throws NotFoundException if the given ID does not exist.
   *
   * @return String The string data associated with the resource,
   * stripped of styled text information.
   */
  public String getString(int id) throws NotFoundException {
      CharSequence res = getText(id);
      if (res != null) {
          return res.toString();
      }
      throw new NotFoundException("String resource ID #0x"
                                  + Integer.toHexString(id));
  }

 

看到這里我想大家就都明白了，Resources類的中getString(int id)方法其實就是調用了Resources類的getText(int id)方法后，多做了一個toString()處理，那么也就是說，我們要討論的問題的結論就可以理解為：Context類中的getString(int resId)==getText(int resId).toString()。

 

更直觀一點，我們來做個小demo：

首先，在Strings中定義兩個string資源：

<string name="get_text"><b>getText</b></string>
<string name="get_string"><b>getString</b></string>

 

接着，在layout文件中定義兩個TextView，分別是textView1和textView2（代碼省略）。

最后，分別使用getText(int resId)和getString(int resId)獲取上面兩個資源，並在textView1和textView2中顯示：

CharSequence charSequence = getText(R.string.get_text);
String str = getString(R.string.get_string);
((TextView)findViewById(R.id.textView1)).setText(charSequence);
((TextView)findViewById(R.id.textView2)).setText(str);

 

結果一目了然：