/**
 * @author LiuYan
 * @date 2021年11月15日 8:21
 */
public class Part08 {
 public static void main(String[] args) {
 // String字符串是不可变的,采用拼接的方式会在内存中产生大量的对象并且效率低
 long startTime = System.currentTimeMillis();
 String str = "";
 for (int i = 0; i < 9999; i++) {
 str += i;
 }
 long endTime = System.currentTimeMillis();
 System.out.println(String.format("string字符串拼接花费时间: %s毫秒", endTime - startTime));
 //StringBuffer和StringBuilder是可变的字符串,不会产生大量对象并且效率高
 long startBufferTime = System.currentTimeMillis();
 StringBuffer stringBuffer = new StringBuffer();
 for (int i = 0; i < 99999; i++) {
 stringBuffer.append(i);
 }
 long endBufferTime = System.currentTimeMillis();
 System.out.println(String.format("stringBuffer字符串拼接花费时间: %s毫秒", endBufferTime - startBufferTime));


 long startBuilderTime = System.currentTimeMillis();
 StringBuilder stringBuilder = new StringBuilder();
 for (int i = 0; i < 99999; i++) {
 stringBuilder.append(i);
 }
 long endBuilderTime = System.currentTimeMillis();
 System.out.println(String.format("stringBuilder字符串拼接花费时间: %s毫秒", endBuilderTime - startBuilderTime));
 /**
 * StringBuffer和StringBuilder:
 * append 链式追加调用
 * insert 指定位置插入元素
 * delete删除指定位置的元素
 */
 }
}