# Use Listview & CheckTextView & Alertdialog
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劉冠呈 資工三Ｂ
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# 可X可熟x紅茶
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## 成品
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## STEPT 1 Create a listview
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## STPET 2 Create a new xml layout
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## STEPT 3 Create a CheckTextView
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## STEPT 4 Write java code!!
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### 宣告變數（MainActivity.java）
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## 設定有幾個item（MainActivity.java）
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## 設定 item 的點擊事件（MainActivity.java）
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## 設定 Adapter （適配器）
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## 什麼是 Adapter?
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「android.widget.Adapter」是一個Java介面(interface)，是一個規範Adapter應該實作什麼方法的規範，也可說是一個家族的最高層成員，所有在它底下的類別都要實作它所訂定的方法，如getCount方法可取得清單中的項目數量、getView方法可得到特定展示的元件(View)等。
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## 還是不懂？
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- List_adapter.java
public class ListAdepter extends BaseAdapter {
private Activity activity;
private List<String> mList;
private static LayoutInflater inflater = null;
public ListAdepter(activity a, List<String> list)
{
activity = a;
mList = list;
inflater = (LayoutInflater) activity.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
}
public int getCount()
{
return mList.size();
}
public Object getItem(int position)
{
return position;
}
public long getItemId(int position)
{
return position;
}
public View getView(int position, View convertView, ViewGroup parent)
{
View vi = convertView;
if(convertView==null)
{
vi = inflater.inflate(R.layout.listview_item, null);
}
CheckedTextView chkBshow = (CheckedTextView) vi.findViewById(R.id.check);
chkBshow.setText(mList.get(position).toString());
return vi;
}
}
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## 什麼是Alertdialog?
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## 設定 alertdialog
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- MainActivity.java
public class MainActivity extends AppCompatActivity {
List<String> list; // 用來設定商品項目
ListView listview;
List<Boolean> listShow; // 這個用來記錄哪幾個 item 是被打勾的
int total = 0; // 用來記錄你總共花多少錢
Button button;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
listview = findViewById(R.id.ListView);
listShow = new ArrayList<Boolean>();
list = new ArrayList<String>();
list.add("熟x紅茶 50元");
listShow.add(false);
list.add("熟x冷露 50元");
listShow.add(false);
list.add("春x綠茶 50元");
listShow.add(false);
list.add("春x冰茶 50元");
listShow.add(false);
list.add("白x歐雷 50元");
listShow.add(false);
list.add("春x紅茶 50元");
listShow.add(false);
list.add("春x冷露 50元");
listShow.add(false);
listview.setOnItemClickListener(new AdapterView.OnItemClickListener() {
public void onItemClick(AdapterView<?> parent, View v, int position, long id) {
CheckedTextView chkItem = v.findViewById(R.id.check);
chkItem.setChecked(!chkItem.isChecked());
if (listShow.get(position) == false) {
listShow.set(position, true);
total += 50;
} else {
listShow.set(position, false);
total -= 50;
}
listShow.set(position, chkItem.isChecked());
}
});
ListAdepter adapterItem = new ListAdepter(this, list);
listview.setAdapter(adapterItem);
button = findViewById(R.id.button);
button.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
new AlertDialog.Builder(MainActivity.this)
.setTitle("是否要給拎北錢")
.setMessage("給拎北錢" + total)
.setPositiveButton("給拎北錢", new DialogInterface.OnClickListener() {
@Override
public void onClick(DialogInterface dialog, int which) {
return;
}
})
.setNeutralButton("我再想想", new DialogInterface.OnClickListener() {
@Override
public void onClick(DialogInterface dialog, int which) {
return;
}
}).show();
}
});
}
}
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