public class PerformanceTester {
public static final int TIMES=100000;
public static abstract class Tester{
private String operation;
public Tester(String operation){this.operation=operation;}
public abstract void test(List<String> list);
public String getOperation(){return operation;}
}
static Tester iteraTester=new Tester(“iterate”) {//执行迭代操作的匿名类
public void test(List<String> list) {
for(int i=0;i<10;i++){
Iterator<String> it=list.iterator();
while (it.hasNext()) {
it.next();
}
}
}
};
static Tester getTester=new Tester(“get”) {//执行随机访问操作的匿名类
public void test(List<String> list) {
for(int i=0;i<list.size();i++){
for(int j=0;j<10;j++ )
list.get(i);
}
}
};
static Tester insertTester=new Tester(“insert”) {//执行插入操作的匿名类
public void test(List<String> list) {
ListIterator<String> it=list.listIterator(list.size()/2);//从列表的中间开始
for(int i=0;i<TIMES/2;i++){
it.add(“Hello”);
}
}
};
static Tester removeTester=new Tester(“remove”) {//执行删除操作的匿名类
public void test(List<String> list) {
ListIterator<String> it=list.listIterator();
while(it.hasNext()){
it.next();
it.remove();
}
}
};
static public void testJavaArray(List<String> list){
Tester[] testers={iteraTester,getTester};
test(testers, list);
}
static public void testList(List<String> list){
Tester[] testers={insertTester,iteraTester,getTester,removeTester};
test(testers,list);
}
private static void test(Tester[] testers, List<String> list) {
for(int i=0;i<testers.length;i++){
System.out.print(testers[i].getOperation()+”操作: “);
long t1=System.currentTimeMillis();
testers[i].test(list);
long t2=System.currentTimeMillis();
System.out.print(t2-t1+” ms”);
System.out.println();
}
}
public static void main(String[] args) {
List<String> list=null;
//测试Java数组
System.out.println(“—-测试Java数组—-“);
String[] ss=new String[TIMES];
Arrays.fill(ss, “Hello”);
list=Arrays.asList(ss);
testJavaArray(list);
ss=new String[TIMES/2];
Collection<String> col=Arrays.asList(ss);
//测试Vector
System.out.println(“—-测试Vector—-“);
list=new Vector<String>();
list.addAll(col);
testList(list);
//测试LinkedList
System.out.println(“—-测试LinkedList—-“);
list=new LinkedList<String>();
list.addAll(col);
testList(list);
//测试ArrayList
System.out.println(“—-测试ArrayList—-“);
list=new ArrayList<String>();
list.addAll(col);
testList(list);
}
}
