【移動(dòng)應(yīng)用開發(fā)技術(shù)】androidlistView性能優(yōu)化

packagecom.example.ex_000_example;importjava.util.ArrayList;importandroid.os.Bundle;importandroid.app.Activity;importandroid.util.Log;importandroid.view.LayoutInflater;importandroid.view.Menu;importandroid.view.View;importandroid.view.ViewGroup;importandroid.view.View.OnClickListener;importandroid.widget.BaseAdapter;importandroid.widget.ImageView;importandroid.widget.ListView;importandroid.widget.TextView;publicclassMainActivityextendsActivityimplementsOnClickListener{

//準(zhǔn)備好的圖片資源 privateint[]p_w_picpathList=newint[]{R.drawable.qq0,R.drawable.qq1, R.drawable.qq2,R.drawable.qq3,R.drawable.qq4,R.drawable.qq5, R.drawable.qq6,R.drawable.qq7,R.drawable.qq8,R.drawable.qq9, R.drawable.qq10,R.drawable.qq11,R.drawable.qq12,R.drawable.qq13, R.drawable.qq14}; privateArrayList<MyDate>dateList=newArrayList<MyDate>(); @Override protectedvoidonCreate(BundlesavedInstanceState){ super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); //準(zhǔn)備數(shù)據(jù) for(inti=0;i<p_w_picpathList.length;i++){ MyDatemyDate=newMyDate("數(shù)據(jù)來了"+i,p_w_picpathList[i]); dateList.add(myDate); } ListViewlistView=(ListView)findViewById(R.id.listView1); MyAdaptermyAdapter=newMyAdapter(); //設(shè)置適配器 listView.setAdapter(myAdapter); }

//減少控件查找次數(shù) classViewHolder{ TextViewtextView; ImageViewp_w_picpathView; } classMyAdapterextendsBaseAdapter{ //設(shè)定每行的樣式以及顯示 @Override publicViewgetView(intposition,ViewconvertView,ViewGroupparent){ Viewinflate=null; ViewHolderholder=null; if(convertView==null){ holder=newViewHolder(); //得到布局轉(zhuǎn)換器 LayoutInflaterinflater=getLayoutInflater(); //將布局xml文件轉(zhuǎn)換成布局對(duì)象 inflate=inflater.inflate(R.layout.list_item,null); //查找控件，一定要查找該布局對(duì)象上有的控件 holder.textView=(TextView)inflate .findViewById(R.id.textView1); holder.p_w_picpathView=(ImageView)inflate .findViewById(R.id.p_w_picpathView1); //將保存控件的對(duì)象存入行布局對(duì)象的tag中 inflate.setTag(holder); }else{ //讓那個(gè)已經(jīng)完全消失的布局對(duì)象，去替代即將出現(xiàn)的 inflate=convertView; //從行布局對(duì)象中取出之前存好的控件 holder=(ViewHolder)inflate.getTag(); } //根據(jù)position從容器中取出數(shù)據(jù) MyDatemyDate=dateList.get(position); //將數(shù)據(jù)顯示到控件上 holder.textView.setText(myDate.title); holder.p_w_picpathView.setImageResource(myDate.p_w_picpath); returninflate; } //決定了listview顯示的行數(shù) @Override publicintgetCount(){ //TODOAuto-generatedmethodstub returndateList.size(); } @Override publicObjectgetItem(intposition){ //TODOAuto-generatedmethodstub returnnull; } @Override publiclonggetItemId(intposition){ //TODOAuto-generatedmethodstub return0; } } @Override publicbooleanonCreateOptionsMenu(Menumenu){ //Inflatethemenu;thisaddsitemstotheactionbarifitispresent. getMenuInflater().inflate(R.menu.main,menu); returntrue; }

classMyDate