第一次做的app

package com.example.kpk.myapplicationfinal;

import android.content.DialogInterface;
import android.content.Intent;
import android.support.v7.app.AlertDialog;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.text.TextUtils;
import android.view.LayoutInflater;
import android.view.Menu;
import android.view.MenuItem;
import android.view.SubMenu;
import android.view.View;
import android.widget.AdapterView;
import android.widget.ArrayAdapter;
import android.widget.EditText;
import android.widget.ListView;
import android.widget.TextView;
import android.widget.Toast;

import java.util.Random;

public class MainActivity extends AppCompatActivity
        implements AdapterView.OnItemClickListener, AdapterView.OnItemLongClickListener {


    String[] aMemo = { // 預設的備忘內容
            "1. 按一下可以編輯備忘",
            "2. 長按可以清除備忘","3.","4.","5.","6.","7.","8.","9.","10.","11.","12.","13.","14.","15." };
    ListView lv; // 顯示備忘錄的 ListView
    ArrayAdapter<String> aa; // ListView 與備忘資料的橋樑
    TextView txv2;



    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        lv = (ListView)findViewById(R.id.listView);
        aa = new ArrayAdapter<>(this,
                android.R.layout.simple_list_item_1, aMemo);

        lv.setAdapter(aa);    //設定 listView1 的內容

        //設定 listView1 被按一下的監聽器
        lv.setOnItemClickListener(this);
        //設定 listView1 被長按的監聽器
        lv.setOnItemLongClickListener(this);

        txv2= (TextView) findViewById(R.id.txv2);



    }

    public void onItemClick(AdapterView<?> a, View v, int pos, long id) {
        Intent it = new Intent(this, tw.com.flag.ch08_memo.Edit.class);
        it.putExtra("備忘", aMemo[pos]);      //附加編號
//        it.putExtra("備忘", aMemo[pos]); //附加備忘項目的內容
        startActivityForResult(it, pos); //啟動 Edit 並以項目位置為識別碼
    }

    public boolean onItemLongClick(AdapterView<?> a, View v, int pos, long id) {
        aMemo[pos] = (pos+1) + "."; //將內容清除 (只剩編號)
        aa.notifyDataSetChanged();  //通知 Adapter 要更新陣列內容
        return true;                //傳回 true 表示此事件已處理
    }

    protected void onActivityResult(int requestCode, int resultCode, Intent it) {
        if(resultCode == RESULT_OK) {
            aMemo[requestCode] = it.getStringExtra("備忘"); // 使用傳回的資料更新陣列內容
            aa.notifyDataSetChanged(); // 通知 Adapter 陣列內容有更新
        }
    }


    public boolean onCreateOptionsMenu(Menu menu) {

        menu.add(Menu.NONE, Menu.FIRST, Menu.NONE, "抽獎");
        menu.add(Menu.NONE, Menu.FIRST + 1, Menu.NONE, "離開程式");
        return super.onCreateOptionsMenu(menu);
    }
    public boolean onOptionsItemSelected(MenuItem item) {  //處理按下Menu Item以後的動作
        switch(item.getItemId()){

            case Menu.FIRST:
//               lv.getAdapter().getItem(new Random().nextInt(lv.getCount()));
//               lv.getAdapter().getItem(new Random().nextInt(lv.getCount()))).toString());
                AlertDialog.Builder bdr = new AlertDialog.Builder(this);
                bdr.setMessage((lv.getAdapter().getItem(new Random().nextInt(lv.getCount()))).toString());
                bdr.setTitle("您抽中了");        // 加入標題
                bdr.setIcon(android.R.drawable.btn_star_big_on); // 加入圖示
                bdr.setCancelable(true);   // 允許按返回鍵關閉交談窗
                bdr.setPositiveButton("ok",null);
                bdr.show();
                break;

            case Menu.FIRST + 1:
                new AlertDialog.Builder(MainActivity.this)
                        .setTitle("離開此程式")
                        .setMessage("你確定要離開？")
                        .setPositiveButton("是", new DialogInterface.OnClickListener() {

                            @Override
                            public void onClick(DialogInterface dialog, int which) {
                                finish();
                            }
                        })
                        .setNegativeButton("否", new DialogInterface.OnClickListener() {

                            @Override
                            public void onClick(DialogInterface dialog, int which) {
                            }
                        })
                        .show();
                break;

        }

        return super.onOptionsItemSelected(item);
    }
}