[英]How to Add imagebutton to child of Expandable ListView on Android?
我有以下代碼來創建Expandable ListView:
public class Menu extends ExpandableListActivity {
int l;
ExpandableListAdapter mAdapter;
ImageButton add = (ImageButton) findViewById(R.id.imageAdd);
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.week_menu);
final String NAME = "NAME";
final String EVENT = "EVENT";
l = getIntent().getExtras().getInt("nilai");
List<Map<String, String>> createGroupList = new ArrayList<Map<String, String>>();
List<List<Map<String, String>>> createChildList = new ArrayList<List<Map<String, String>>>();
for (int i = 0, k = 0; i < 5; i++) {
Map<String, String> curGroupMap = new HashMap<String, String>();
createGroupList.add(curGroupMap);
if (i == 0)
curGroupMap.put(NAME, "Breakfast 07.00");
else if (i == 1)
curGroupMap.put(NAME, "Snack 10.00");
else if (i == 2)
curGroupMap.put(NAME, "Lunch 12.00");
else if (i == 3)
curGroupMap.put(NAME, "Snack 16.00");
else if (i == 4)
curGroupMap.put(NAME, "Dinner 19.00");
List<Map<String, String>> children = new ArrayList<Map<String, String>>();
if (i == 1 || i == 3)
{
for (int j = 0; j < 6; j++, k++) {
if(AdapterDB.optimal_chromosomes.get(l).gens[k].id != 164) {
Map<String, String> curChildMap = new HashMap<String, String>();
children.add(curChildMap);
curChildMap.put(NAME, AdapterDB.optimal_chromosomes.get(l).gens[k].name);
curChildMap.put(EVENT, "" + add);
}
}
}
else
{
for (int j = 0; j < 12; j++, k++) {
if(AdapterDB.optimal_chromosomes.get(l).gens[k].id != 164) {
Map<String, String> curChildMap = new HashMap<String, String>();
children.add(curChildMap);
curChildMap.put(NAME, AdapterDB.optimal_chromosomes.get(l).gens[k].name);
curChildMap.put(EVENT, "" + add);
}
}
}
/*
add.setOnClickListener(new OnClickListener() {
public void onClick(View v) {
}
});*/
createChildList.add(children);
}
mAdapter = new SimpleExpandableListAdapter(this, createGroupList, android.R.layout.simple_expandable_list_item_1, new String [] {NAME}, new int[]{android.R.id.text1}, createChildList, android.R.layout.simple_expandable_list_item_2, new String[] {NAME, EVENT}, new int [] {android.R.id.text2});
setListAdapter(mAdapter);
}
這是錯誤,java.lang.NullPointerException在
ImageButton add = (ImageButton) findViewById(R.id.imageAdd);
... 任何想法? 我想在Android中的孩子上添加imagebutton。 如何解決並使其可點擊? 謝謝
setContentView執行后,需要在onCreate按鈕中初始化變量。
ImageButton add;
並在onCreate方法中
setContentView(R.layout.week_menu);
add = (ImageButton) findViewById(R.id.imageAdd);
findViewById在setContentView中指定的布局內查找視圖。 但這還沒有發生。 所以會發生錯誤。
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