Listview
package com.example.hp.list_1; import android.arch.lifecycle.ViewModelStoreOwner; import android.os.Bundle; import android.support.v7.app.AppCompatActivity; import android.view.ContextMenu; import android.view.MenuItem; import android.view.View; import android.widget.AdapterView; import android.widget.ArrayAdapter; import android.widget.Button; import android.widget.EditText; import android.widget.ListView; import android.widget.TextView; import java.util.ArrayList; import java.util.List; public class MainActivity extends AppCompatActivity { EditText cl,nm,mz; Button button; ListView listView; List<String> list=new ArrayList<String>(); @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); cl=(EditText)findViewById(R.id.bj); nm=(EditText)findViewById(R.id.xh); mz=(EditText)findViewById(R.id.xm); listView=(ListView)findViewById(R.id.list); button=(Button)findViewById(R.id.send); button.setOnClickListener(new View.OnClickListener(){ @Override public void onClick(View view){ list.add(" "+cl.getText().toString()+" "+nm.getText().toString()+" "+mz.getText().toString()); //ArrayAdapter<String>adapter=new ArrayAdapter<String>(MainActivity.this,android.R.layout.simple_list_item_1,list); ArrayAdapter<String>adapter=new ArrayAdapter<String>(MainActivity.this,android.R.layout.simple_list_item_1,list); listView.setAdapter(adapter); } }); listView.setOnCreateContextMenuListener(new View.OnCreateContextMenuListener(){ @Override public void onCreateContextMenu(ContextMenu menu, View v, ContextMenu.ContextMenuInfo menuInfo) { menu.add(0,0,0,"删除"); } }); } public boolean onContextItemSelected(MenuItem item){ AdapterView.AdapterContextMenuInfo info=(AdapterView.AdapterContextMenuInfo)item.getMenuInfo(); int id=(int)info.id; list.remove(id); ArrayAdapter<String>adapter=new ArrayAdapter<String>(MainActivity.this,android.R.layout.simple_list_item_1,list); listView.setAdapter(adapter); return true; } }数据库
DBAdapter
import android.content.ContentValues; import android.content.Context; import android.database.Cursor; import android.database.sqlite.SQLiteDatabase; import android.database.sqlite.SQLiteException; import android.database.sqlite.SQLiteOpenHelper; public class DBAdapter { public static final String dbname="student.db"; public static final String Sno="Sno"; public static final String Sname="Snmae"; public static final String Sclass="Sclass"; public static final String Id="_id"; public static final String Table="studentinfo"; public static SQLiteDatabase db; public final Context context; public DBhelper dBhelper; public DBAdapter(Context context1) { context=context1; } public void open() throws SQLiteException { dBhelper=new DBhelper(context,dbname,null,1); try { db=dBhelper.getWritableDatabase(); } catch (Exception e) { db=dBhelper.getReadableDatabase(); } } public long insert(Student s) { ContentValues cv=new ContentValues(); cv.put(Sno,s.sno); cv.put(Sname,s.sname); cv.put(Sclass,s.Class); return db.insert(Table,null,cv); } public Student[] find() { Cursor c=db.query(Table,new String []{Sclass,Sno,Sname},null,null,null,null,null); if(c==null) return null; return convert(c); } public long delete() { return db.delete(Table,null,null); } public long deleteOne(String sno) { return db.delete(Table,"Sno="+sno,null); } public long updateBySno(String sno,Student s) { ContentValues cv=new ContentValues(); cv.put(Sno,s.sno); cv.put(Sname,s.sname); cv.put(Sclass,s.Class); return db.update(Table,cv,"Sno="+sno,null); } public Student[]convert(Cursor c) { int count=c.getCount(); if(count==0||!c.moveToFirst()) { return null; } Student students[]=new Student[count]; for(int i=0;i<count;i++) { students[i]=new Student(); students[i].sno=c.getString(c.getColumnIndex(Sno)); students[i].sname=c.getString(c.getColumnIndex(Sname)); students[i].Class=c.getString(c.getColumnIndex(Sclass)); c.moveToNext(); } return students; } private static class DBhelper extends SQLiteOpenHelper { public DBhelper(Context context, String name, SQLiteDatabase.CursorFactory factory, int version) { super(context,name,factory,version); } private static final String create="create table "+Table+"("+Id+" integer primary key autoincrement, "+Sclass +" text, "+Sno+" text, "+Sname+" text)"; public void onCreate(SQLiteDatabase db) { db.execSQL(create); } public void onUpgrade(SQLiteDatabase db,int oldversion,int newversion) { db.execSQL("drop table if exists "+Table); onCreate(db); } } public void close() { if(db!=null) { db.close(); db=null; } } }
MainActivity
import android.app.Activity; import android.database.Cursor; import android.os.Bundle; import android.view.ContextMenu; import android.view.MenuItem; import android.view.View; import android.widget.AdapterView; import android.widget.ArrayAdapter; import android.widget.Button; import android.widget.EditText; import android.widget.ListView; import java.util.ArrayList; import java.util.List; public class MainActivity extends Activity { Button add,update,clear,deleteAll,show,deleteone; EditText t1,t2,t3,input; ListView listView;List<String> list=new ArrayList<String>(); DBAdapter adapter; protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); t1=(EditText)findViewById(R.id.e1); t2=(EditText)findViewById(R.id.e2); t3=(EditText)findViewById(R.id.e3); input=(EditText)findViewById(R.id.input); listView=(ListView)findViewById(R.id.listview); add=(Button)findViewById(R.id.add); update=(Button)findViewById(R.id.update); clear=(Button)findViewById(R.id.clear); deleteAll=(Button)findViewById(R.id.deleteAll); deleteone=(Button)findViewById(R.id.deleteone); show=(Button)findViewById(R.id.show); adapter=new DBAdapter(this); adapter.open(); add.setOnClickListener(new View.OnClickListener() { @Override public void onClick(View view) { Student s=new Student(); s.Class=t1.getText().toString(); s.sno=t2.getText().toString(); s.sname=t3.getText().toString(); adapter.insert(s); list.add(" "+t1.getText().toString()+" "+t2.getText().toString()+" "+t3.getText().toString()); ArrayAdapter<String>adapter=new ArrayAdapter<String>(MainActivity.this,android.R.layout.simple_list_item_1,list); listView.setAdapter(adapter); } }); clear.setOnClickListener(new View.OnClickListener() { @Override public void onClick(View view) { list.clear(); ArrayAdapter<String>adapter=new ArrayAdapter<String>(MainActivity.this,android.R.layout.simple_list_item_1,list); listView.setAdapter(adapter); } }); update.setOnClickListener(new View.OnClickListener() { @Override public void onClick(View view) { Student s=new Student(); s.Class=t1.getText().toString(); s.sno=t2.getText().toString(); s.sname=t3.getText().toString(); adapter.updateBySno(input.getText().toString(),s); } }); deleteone.setOnClickListener(new View.OnClickListener(){ @Override public void onClick(View view) { adapter.deleteOne(input.getText().toString()); } }); deleteAll.setOnClickListener(new View.OnClickListener() { @Override public void onClick(View view) { adapter.delete(); list.clear(); ArrayAdapter<String>adapter=new ArrayAdapter<String>(MainActivity.this,android.R.layout.simple_list_item_1,list); listView.setAdapter(adapter); } }); show.setOnClickListener(new View.OnClickListener() { @Override public void onClick(View view) { list.clear(); ArrayAdapter<String>adapters=new ArrayAdapter<String>(MainActivity.this,android.R.layout.simple_list_item_1,list); listView.setAdapter(adapters); Student students[]=adapter.find(); for(int i=0;i<students.length;i++) { list.add(students[i].toString()); } listView.setAdapter(adapters); } }); listView.setOnCreateContextMenuListener(new View.OnCreateContextMenuListener() { @Override public void onCreateContextMenu(ContextMenu contextMenu, View view, ContextMenu.ContextMenuInfo contextMenuInfo) { contextMenu.add(0,0,0,"删除"); } }); } public boolean onContextItemSelected(MenuItem item) { AdapterView.AdapterContextMenuInfo info=(AdapterView.AdapterContextMenuInfo)item.getMenuInfo(); int id=(int)info.id; list.remove(id); String s[]=list.get(id).split(" "); t1.setText(""+s[1]); // adapter.deleteOne(s[1]); ArrayAdapter<String>adapter=new ArrayAdapter<String>(MainActivity.this,android.R.layout.simple_list_item_1,list); listView.setAdapter(adapter); return true; } }
Student
public class Student { public String sno; public String sname; public String Class; public String toString() { return Class+" "+sno+" "+sname; } }
秒表
MainActivity
import android.app.Activity; import android.os.Bundle; import android.os.Handler; import android.view.View; import android.widget.Button; import android.widget.TextView; public class MainActivity extends Activity implements Button.OnClickListener { Button clear,start,stop; TextView textView; boolean isStop=false,isStart=true; String result; int sec=0,min=0,hour=0; Handler handler=new Handler(); Runnable run=new Runnable() { @Override public void run() { if(!isStop){ sec=sec+1; if(sec==60){ min=min+1; sec=0; } if(min==60){ hour++; min=0; } if(hour<10) result="0"+hour; else result=""+hour; if(min<10) result=result+":0"+min; else result=result+":"+min; if(sec<10) result=result+":0"+sec; else result=result+":"+sec; textView.setText(result); handler.postDelayed(this,1000); } } }; protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); clear=(Button)findViewById(R.id.clear); start=(Button)findViewById(R.id.start); stop=(Button)findViewById(R.id.stop); textView=(TextView)findViewById(R.id.show); clear.setOnClickListener(this); start.setOnClickListener(this); stop.setOnClickListener(this); } public void onClick(View view){ switch (view.getId()){ case R.id.clear: clear(); break; case R.id.start: if(isStart){ clock().run(); isStart=false; break; } break; case R.id.stop: isStart=true; isStop=true; break; } } public Thread clock() { isStop=false; return new Thread(run); } public void clear() { isStart=true; isStop=true; textView.setText("00:00:00"); sec = min = hour = 0; } }