java五种拼接字符串的方法



java五种拼接字符串的方法

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package test; import org.apache.commons.lang.StringUtils; public class CutString {      //性能最差      public String testPlus() {          String s = "" ;          for ( int i = 0 ; i < 10000 ; i++) {              s = s + String.valueOf(i);          }          return s;      }      //较好      public String testConcat() {          String s = "" ;          for ( int i = 0 ; i < 10000 ; i++) {              s = s.concat(String.valueOf(i));          }          return s;      }            //性能与testStringBuffer相差无几，比其要好      public String testJoin() {          String[] list = new String[ 10000 ];          for ( int i = 0 ; i < 10000 ; i++) {              list[i] = String.valueOf(i);          }          return StringUtils.join(list, "" );      }      public String testStringBuffer() {          StringBuffer sb = new StringBuffer();          long l1 = System.currentTimeMillis();          for ( int i = 0 ; i < 10000 ; i++) {              sb.append(String.valueOf(i));          }          long l2 = System.currentTimeMillis();          System.out.println(l2-l1);          return sb.toString();      }            //性能最高的方法      public void testStringBuilder() {          StringBuilder sb = new StringBuilder();          for ( int i = 0 ; i < 100000 ; i++) {              sb.append(String.valueOf(i));          }          sb.toString();      }      public static void main(String[] args) {          System.out.println( new CutString().testStringBuffer());      } }