實驗三 UI設計(二)
實驗目的:
學習使用ListView
實驗要求:
1. 實現一個列表,其中顯示班級學號姓名,提供添加功能,如需要刪去某一項,長按該項,通過彈出菜單顯示刪除功能。
代碼:
MainActivity.java
package com.example.walker.exp3;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.ContextMenu;
import android.view.MenuItem;
import android.view.View;
import android.widget.AdapterView;
import android.widget.Button;
import android.widget.EditText;
import android.widget.ListView;
import android.widget.SimpleAdapter;
import android.widget.Toast;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
public class MainActivity extends AppCompatActivity {
private Button btn_add;
private EditText et_name;
private EditText et_class;
private EditText et_numer;
private ListView listview;
private SimpleAdapter simpleAdapter;
private List<Map<String, Object>> Datas = new ArrayList<Map<String, Object>>();
//String number;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
//實例化數據集
listview = (ListView) findViewById(R.id.listview);
et_class = (EditText) findViewById(R.id.et_class);
et_name = (EditText) findViewById(R.id.et_name);
et_numer = (EditText) findViewById(R.id.et_number);
btn_add = (Button) findViewById(R.id.btn_add);
//爲 ListView 的所有 item 註冊 ContextMenu
// this.registerForContextMenu(listview);
//設置創建上下文菜單的監聽
listview.setOnCreateContextMenuListener(this);
////設置按鈕的監聽
btn_add.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
if (et_class.getText().toString().trim().equals("") || et_numer.getText().toString().trim().equals("") || et_name.getText().toString().trim().equals("")) {
Toast.makeText(MainActivity.this, "請輸入正確數據", Toast.LENGTH_SHORT).show();
} else {
Map<String, Object> item = new HashMap<String, Object>();
item.put("class", et_class.getText().toString());
item.put("number", et_numer.getText().toString());
item.put("name", et_name.getText().toString());
Datas.add(item);
simpleAdapter.notifyDataSetChanged();
Toast.makeText(MainActivity.this, "添加數據成功", Toast.LENGTH_SHORT).show();
}
}
});
//map對象中的key的數組, 用於得到對應的value
String[] from = {"class", "number", "name"};
//Item佈局文件中的子view的id的數組
int[] to = {R.id.tv_class, R.id.tv_number, R.id.tv_name};
// /設置適配器
simpleAdapter = new SimpleAdapter(this, Datas, R.layout.item_view, from, to);
listview.setAdapter(simpleAdapter);
}
public void onCreateContextMenu(ContextMenu menu, View v,
ContextMenu.ContextMenuInfo menuInfo) {
super.onCreateContextMenu(menu, v, menuInfo);
//添加菜單項
menu.add(0, 1, 0, "刪除");
}
@Override
public boolean onContextItemSelected(MenuItem item) {
AdapterView.AdapterContextMenuInfo menuInfo = (AdapterView.AdapterContextMenuInfo) item.getMenuInfo();
int pos = (int) listview.getAdapter().getItemId(menuInfo.position);
Datas.remove(pos);
// if (Datas.remove(pos) != null) {
// System.out.println("success");
// } else {
// System.out.println("failed");
// }
simpleAdapter.notifyDataSetChanged();
Toast.makeText(getBaseContext(), "刪除此項", Toast.LENGTH_SHORT).show();
return super.onContextItemSelected(item);
}
}
activity_main.xml
<?xml version="1.0" encoding="utf-8"?> <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" xmlns:tools="http://schemas.android.com/tools" android:layout_width="match_parent" android:layout_height="match_parent" android:orientation="vertical" tools:context=".MainActivity" android:background="@color/layout"> <LinearLayout android:layout_width="match_parent" android:layout_height="wrap_content" android:orientation="horizontal"> <TextView android:layout_width="wrap_content" android:layout_height="wrap_content" android:text="班級:" android:textSize="20sp" /> <EditText android:id="@+id/et_class" android:layout_width="140dp" android:layout_height="wrap_content" android:textSize="20sp" android:inputType="text"/> </LinearLayout> <LinearLayout android:layout_width="match_parent" android:layout_height="wrap_content" android:orientation="horizontal"> <TextView android:layout_width="wrap_content" android:layout_height="wrap_content" android:text="學號:" android:textSize="20sp"/> <EditText android:id="@+id/et_number" android:layout_width="140dp" android:layout_height="wrap_content" android:textSize="20sp" android:inputType="number"/> </LinearLayout> <LinearLayout android:layout_width="match_parent" android:layout_height="wrap_content" android:orientation="horizontal"> <TextView android:layout_width="wrap_content" android:layout_height="wrap_content" android:text="姓名:" android:textSize="20sp"/> <EditText android:id="@+id/et_name" android:layout_width="140dp" android:layout_height="wrap_content" android:textSize="20sp" /> </LinearLayout> <LinearLayout android:layout_width="match_parent" android:layout_height="wrap_content" android:orientation="horizontal"> <Button android:id="@+id/btn_add" android:layout_width="wrap_content" android:layout_height="wrap_content" android:text="@string/app_button" android:textSize="20sp" android:background="@color/app_bk"/> </LinearLayout> <LinearLayout android:layout_width="match_parent" android:layout_height="wrap_content" android:orientation="horizontal"> <TextView android:layout_width="0dp" android:layout_height="wrap_content" android:layout_weight="1" android:text="班級" android:textSize="20sp"/> <TextView android:layout_width="0dp" android:layout_height="wrap_content" android:layout_weight="1" android:text="學號" android:textSize="20sp"/> <TextView android:layout_width="0dp" android:layout_height="wrap_content" android:layout_weight="1" android:text="姓名" android:textSize="20sp"/> </LinearLayout> <LinearLayout android:layout_width="match_parent" android:layout_height="wrap_content" android:orientation="horizontal"> <ListView android:id="@+id/listview" android:layout_width="match_parent" android:layout_height="match_parent"></ListView> </LinearLayout> </LinearLayout>
item_view.xml
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent">
<TextView
android:id="@+id/tv_class"
android:layout_width="0dp"
android:layout_height="wrap_content"
android:layout_weight="1"
android:textSize="20sp"/>
<TextView
android:id="@+id/tv_number"
android:layout_width="0dp"
android:layout_height="wrap_content"
android:layout_weight="1"
android:textSize="20sp"/>
<TextView
android:id="@+id/tv_name"
android:layout_width="0dp"
android:layout_height="wrap_content"
android:layout_weight="1"
android:textSize="20sp"/>
</LinearLayout>