public class MainActivity extends AppCompatActivity {
? ?private GridView gridView;
? ?private SimpleAdapter adapter;?
? ?private List<Map<String,Object>> dataList;

? ?private int[] icon={R.drawable.test,R.drawable.clipboard1,R.drawable.test11,R.drawable.test12};?
? ?private String[]iconName={"設置","天氣","相機","陽光"};

? ?@Override
? ?protected void onCreate(Bundle savedInstanceState) {
? ? ? ?super.onCreate(savedInstanceState);
? ? ? ?setContentView(R.layout.activity_main);
? ? ? ?gridView=(GridView) findViewById(R.id.gridView);
? ? ? ?dataList=new ArrayList<Map<String,Object>>();??
? ? ? ?adapter=new SimpleAdapter(this,getData(),R.layout.item,new String[]{"image","text"},new int[]{R.id.image1,R.id.text1});?
? ? ? ?gridView.setAdapter(adapter);??
? ?}
? ?private List<Map<String,Object>> getData(){
? ? ? ?for(int i=0;i<icon.length;i++){
? ? ? ? ? ?Map<String,Object>map=new HashMap<String,Object>();??
? ? ? ? ? ?map.put("image1",icon[i]);
? ? ? ? ? ?map.put("text1",iconName[i]);
? ? ? ? ? ?dataList.add(map);?
? ? ? ?}
? ? ? ?return dataList;
? ?}

}

報錯：?Attempt to invoke virtual method 'void android.widget.GridView.setAdapter(android.widget.ListAdapter)' on a null object reference