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

Java代码

1. int idFlag = getResources().getIdentifier(
2. getPackageName() + ":drawable/flag",
3. null, null);
4. // 或是
5. int idFlag = getResources().getIdentifier(
6. "flag", "drawable", getPackageName());

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

Java代码

1. var Drawable[] dw = new Drawable[10];
3. for (int i = 1; i <= 10; i++) {
4. int id = getResources().getIdentifier(
5. "flag" + i,
6. "drawable", getPackageName());
7. dw[i-1] = getResources().getDrawable(id);
8. }

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);   
}

Java代码

1. private void
2. _DumpAllResourceIDs(Class<?> classType)
3. throws IllegalArgumentException {
4. Field[] fIDs = classType.getFields();
6. try {
7. for (int i = 0; i < fIDs.length; i++) {
8. Field fld = fIDs[i];
9. int nID = fld.getInt(null);
10. Log.d("dbg",
11. classType.getSimpleName() + " " +
12. i + ": " +
13. fld.getName() + "=" +
14. nID);
15. }
16. } catch (Exception e) {
17. throw new IllegalArgumentException();
18. }
19. }

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();   
  }   
}  

Java代码

1. import java.lang.reflect.Field;
2. ...
3. _DumpAllResourceIDs(R.layout.class);
4. _DumpAllResourceIDs(R.drawable.class);

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