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实验3布局：
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    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="班级："
            android:textSize="20sp" />

        <EditText
            android:id="@+id/et_class"
            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">

        <TextView
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="学号："
            android:textSize="20sp"/>

        <EditText
            android:id="@+id/et_number"
            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">

        <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="match_parent"
            android:layout_height="wrap_content"
            android:layout_weight="1"
            android:text="班级"
            android:textSize="20sp"/>
        <TextView
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:layout_weight="1"
            android:text="学号"
            android:textSize="20sp"/>
        <TextView
            android:layout_width="match_parent"
            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>

实验3实现：
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);
        //实例化数据集
        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);

        //为 ListView 的所有 item 注册 ContextMenu
        this.registerForContextMenu(listview);
        //实例化SimpleAdapter
        Map<String, Object> map1 = new HashMap<String, Object>();
        map1.put("class", "计算机162");
        map1.put("number", "2016012841");
        map1.put("name", "沈仕瑞");
        Datas.add(map1);
        //设置创建上下文菜单的监听
        //listview.setOnCreateContextMenuListener(this);
        ////设置按钮的监听

        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, "请输入正确数据", 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, "添加数据成功", Toast.LENGTH_SHORT).show();

                }
            }
        });
        //map对象中的key的数组, 用于得到对应的value
        String[] from = {"class", "number", "name"};
        //Item布局文件中的子view的id的数组
        int[] to = {R.id.tv_class, R.id.tv_number, R.id.tv_name};
        // /设置适配器
        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);
        //添加菜单项
        menu.add(0, 1, 0, "删除");
    }

    @Override
    public boolean onContextItemSelected(MenuItem item) {
        AdapterView.AdapterContextMenuInfo menuInfo = (AdapterView.AdapterContextMenuInfo) item.getMenuInfo();
        int pos = (int) listview.getAdapter().getItemId(menuInfo.position);
        if (Datas.remove(pos) != null) {
            System.out.println("success");
        } else {
            System.out.println("failed");
        }
        simpleAdapter.notifyDataSetChanged();
        Toast.makeText(getBaseContext(), "删除此项", Toast.LENGTH_SHORT).show();
        return super.onContextItemSelected(item);
    }

}
实验5布局：
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="vertical" android:layout_width="match_parent"
    android:layout_height="match_parent">

    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="56dp"
        android:orientation="horizontal">

        <TextView
            android:id="@+id/title"
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            android:text="秒  表"
            android:textAlignment="center"
            android:textSize="24sp" />
    </LinearLayout>

    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="74dp"
        android:orientation="horizontal">

        <TextView
            android:id="@+id/hour"
            android:layout_width="wrap_content"
            android:layout_height="match_parent"
            android:layout_weight="1"
            android:textAlignment="center" />

        <TextView
            android:id="@+id/min"
            android:layout_width="wrap_content"
            android:layout_height="match_parent"
            android:layout_weight="1"
            android:textAlignment="center" />

        <TextView
            android:id="@+id/sec"
            android:layout_width="wrap_content"
            android:layout_height="match_parent"
            android:layout_weight="1"
            android:textAlignment="center" />
    </LinearLayout>

    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="64dp"
        android:orientation="horizontal">

        <Button
            android:id="@+id/ret0"
            android:layout_width="wrap_content"
            android:layout_height="match_parent"
            android:layout_weight="1"
            android:text="清 零" />

        <Button
            android:id="@+id/ready"
            android:layout_width="wrap_content"
            android:layout_height="match_parent"
            android:layout_weight="1"
            android:text="计 时" />

        <Button
            android:id="@+id/stop"
            android:layout_width="wrap_content"
            android:layout_height="match_parent"
            android:layout_weight="1"
            android:text="停 止" />
    </LinearLayout>
</LinearLayout>

实验5实现：
package com.example.administrator.sy5;

import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.widget.Button;
import android.widget.TextView;
import android.os.Handler;
import android.view.View;
import android.view.View.OnClickListener;

public class MainActivity extends AppCompatActivity {

    private TextView Hour;
    private TextView Min;
    private TextView Sec;
    private Button Stop;
    private Button Ready;
    private Button Ret0;
    private boolean isPaused = false;
    private String timeUsed;
    private int timeUsedInsec;

    private Handler uiHandle = new Handler(){
        public void handleMessage(android.os.Message msg) {
            switch(msg.what){
                case 1:
                    if(!isPaused) {
                        addTimeUsed();
                        updateClockUI();
                    }
                    uiHandle.sendEmptyMessageDelayed(1, 1000);
                    break;
                default: break;
            }
        }
    };

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        Hour = (TextView)findViewById(R.id.hour);
        Min = (TextView)findViewById(R.id.min);
        Sec = (TextView)findViewById(R.id.sec);
        Ret0 = (Button)findViewById(R.id.ret0);
        Ready = (Button)findViewById(R.id.ready);
        Stop = (Button)findViewById(R.id.stop);

        Ready.setOnClickListener(new OnClickListener() {
            @Override
            public void onClick(View view) {
                uiHandle.removeMessages(1);
                startTime();
                isPaused = false;
            }
        });

        Stop.setOnClickListener(new OnClickListener() {
            @Override
            public void onClick(View view) {
                isPaused = true;
                timeUsedInsec = 0;
            }
        });

        Ret0.setOnClickListener(new OnClickListener() {
            @Override
            public void onClick(View view) {
                isPaused = true;
                timeUsedInsec = 0;
                Hour.setText("0"+":");
                Min.setText("0" + ":");
                Sec.setText("0");
            }
        });
    }



    @Override
    protected void onPause() {
        // TODO Auto-generated method stub
        super.onPause();
        isPaused = true;
    }

    @Override
    protected void onResume() {
        // TODO Auto-generated method stub
        super.onResume();
        isPaused = false;
    }

    private void startTime(){
        uiHandle.sendEmptyMessageDelayed(1, 1000);
    }


    private void updateClockUI(){
        Hour.setText(getHour()+":");
        Min.setText(getMin() + ":");
        Sec.setText(getSec());
    }

    public void addTimeUsed(){
        timeUsedInsec = timeUsedInsec + 1;
        timeUsed =this.getHour()+":"+ this.getMin() + ":" + this.getSec();
    }

    public CharSequence getHour(){
        int min = timeUsedInsec / 60;
        return String.valueOf(min / 60);
    }

    public CharSequence getMin(){
        return String.valueOf(timeUsedInsec / 60);
    }

    public CharSequence getSec(){
        int sec = timeUsedInsec % 60;
        return sec < 10? "0" + sec :String.valueOf(sec);
    }

}