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package test.lt20;
import java.util.ArrayList;
import java.util.List;
public class Test19 {
public static void main(String[] args) {
// TODO Auto-generated method stub
//jdk8
a1();
//a2();
}
public static void a1() {
List<String> oldList1 = new ArrayList<>();
for (int i = 0; i < 1000000; i++) {
oldList1.add("a:" + i);
}
List<String> newList1 = new ArrayList<>(1000000);
List<String> newList2 = new ArrayList<>(1000000);
String temp = "";
for (int i = 0; i < 1000000; i++) {
temp = oldList1.get(i).split(":")[1];
}
//方式一:普通For循环
long start = System.nanoTime();
for (int i = 0; i < 1000000; i++) {
newList1.add(oldList1.get(i).split(":")[1]);
}
System.out.println("方式一list普通For 最终耗时 = " + ((System.nanoTime() - start) / 100_0000));
List<String> oldList2 = new ArrayList<>();
for (int i = 0; i < 1000000; i++) {
oldList2.add("b:" + i);
}
for (int i = 0; i < 1000000; i++) {
temp = oldList2.get(i).split(":")[1];
}
//方式一:普通For循环
long start1 = System.nanoTime();
for (int i = 0; i < 1000000; i++) {
newList2.add(oldList2.get(i).split(":")[1]);
}
System.out.println("方式一list2普通For 最终耗时 = " + ((System.nanoTime() - start1) / 100_0000));
}
public static void a2() {
List<String> oldList1 = new ArrayList<>();
for (int i = 0; i < 1000000; i++) {
oldList1.add("a:" + i);
}
List<String> oldList2 = new ArrayList<>();
for (int i = 0; i < 1000000; i++) {
oldList2.add("b:" + i);
}
ArrayList<String> newList1 = new ArrayList<>(1000000);
List<String> newList2 = new ArrayList<>(1000000);
String temp = "";
for (int i = 0; i < 1000000; i++) {
temp = oldList1.get(i).split(":")[1];
}
for (int i = 0; i < 1000000; i++) {
temp = oldList2.get(i).split(":")[1];
}
//方式一:普通For循环
long start = System.nanoTime();
for (int i = 0; i < 1000000; i++) {
newList1.add(oldList1.get(i).split(":")[1]);
}
System.out.println("方式一list普通For 最终耗时 = " + ((System.nanoTime() - start) / 100_0000));
//方式一:普通For循环
long start1 = System.nanoTime();
for (int i = 0; i < 1000000; i++) {
newList2.add(oldList2.get(i).split(":")[1]);
}
System.out.println("方式一list2普通For 最终耗时 = " + ((System.nanoTime() - start1) / 100_0000));
}
}
import java.util.ArrayList;
import java.util.List;
public class Test19 {
public static void main(String[] args) {
// TODO Auto-generated method stub
List<String> oldList1 = new ArrayList<>();
for (int i = 0; i < 1000000; i++) {
oldList1.add("a:" + i);
}
List<String> oldList2 = new ArrayList<>();
for (int i = 0; i < 1000000; i++) {
oldList2.add("b:" + i);
}
//方式一:普通For循环
long start = System.nanoTime();
List<String> newList1 = new ArrayList<>(1000000);
List<String> newList2 = new ArrayList<>(1000000);
for (int i = 0; i < 1000000; i++) {
newList1.add(oldList1.get(i).split(":")[1]);
}
System.out.println("方式一list普通For 最终耗时 = " + ((System.nanoTime() - start) / 100_0000));
//方式一:普通For循环
long start1 = System.nanoTime();
for (int i = 0; i < 1000000; i++) {
newList2.add(oldList2.get(i).split(":")[1]);
}
System.out.println("方式一list2普通For 最终耗时 = " + ((System.nanoTime() - start1) / 100_0000));
}
}