判断资源存在与否如判断一个drawable的图片存在及通过id加载图片

留下来以后备用！

int i= getResources().getIdentifier("icon", "drawable", getPackageName()) ;
if(i>0)
{Log.i("aa","aa");}
else
{Log.i("vbv","aa");}

或者

int resID = getResources().getIdentifier("org.loveandroid.androidtest:drawable/gallery_photo_1",null,null);

int resID = getResources ( ). getIdentifier ( "org.anddev.android.testproject:drawable/bug", null, null );
// or
int resID = getResources ( ). getIdentifier ( "bug", "drawable", "org.anddev.android.testproject" );

第一个参数其实

full_package:type/filename_without_ending是这种格式 然后其他的可以为null

int idFlag = getResources().getIdentifier(
getPackageName() + ":drawable/flag",
null, null);
// 或是
int idFlag = getResources().getIdentifier(
"flag", "drawable", getPackageName());

int idFlag = getResources().getIdentifier(   
      getPackageName() + ":drawable/flag",    
      null, null);   
// 或是   
int idFlag = getResources().getIdentifier(   
      "flag", "drawable", getPackageName());  

var Drawable[] dw = new Drawable[10];

for (int i =  1; i <= 10; i++) {
int id = getResources().getIdentifier(
"flag" + i,
"drawable", getPackageName());
dw[i-1] = getResources().getDrawable(id);
}

var Drawable[] dw = new Drawable[10];   
  
for (int i = 1; i <= 10; i++) {   
  int id = getResources().getIdentifier(   
                    "flag" + i,    
                    "drawable", getPackageName());   
  dw[i-1] = getResources().getDrawable(id);   
}

用反射发 可以得到 所有的资源

private void
_DumpAllResourceIDs(Class<?> classType)
throws IllegalArgumentException {
Field[] fIDs = classType.getFields();

try {
for (int i =  0; i < fIDs.length; i++) {
Field fld = fIDs[i];
int nID = fld.getInt(null);
Log.d("dbg",
classType.getSimpleName() + " " +
i + ": " +
fld.getName() + "=" +
nID);
}
} catch (Exception e) {
throw new IllegalArgumentException();
}
}

private void    
  _DumpAllResourceIDs(Class<?> classType)    
    throws IllegalArgumentException {   
  Field[] fIDs = classType.getFields();   
           
  try {   
    for (int i = 0; i < fIDs.length; i++) {   
      Field fld = fIDs[i];   
      int nID = fld.getInt(null);   
      Log.d("dbg",   
        classType.getSimpleName() + " " +    
        i + ": " +    
        fld.getName() + "=" +   
        nID);   
    }   
  } catch (Exception e) {   
    throw new IllegalArgumentException();   
  }   
}  

import java.lang.reflect.Field;
...
_DumpAllResourceIDs(R.layout.class);
_DumpAllResourceIDs(R.drawable.class);

import java.lang.reflect.Field;   
...   
  _DumpAllResourceIDs(R.layout.class);   
  _DumpAllResourceIDs(R.drawable.class);  

结果

R$layout 0: main=2130903040
R$layout 1: small_spinner_dropdown_item=2130903041
R$drawable 0: icon=2130837504