StringBuffer 清空
阿新 • • 發佈：2018-07-13
review delete tle cin delet edit key nts code
幾種方法:
-
方法1:
1 2 3 4 StringBuffer my_StringBuffer =newStringBuffer();my_StringBuffer.append(‘helloworld‘);//添加字符串到StringBuffer中intsb_length = my_StringBuffer.length();// 取得字符串的長度my_StringBuffer.delete(0,sb_length);//刪除字符串從0~sb_length-1處的內容 (這個方法就是用來清除StringBuffer中的內容的) -
方法2:
1 my_StringBuffer.setLength(0);//設置StringBuffer變量的長度為0 -
方法3:也是我以前一直用的
1 my_StringBuffer =newStringBuffer()
幾種方法的效率:
測試程序:
| 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 |
private static void testStringBufferclear() {
StringBuffer sbf = new StringBuffer("wwwwww");
StringBuffer sbi = new StringBuffer("wwwwww");
long s1 = System.currentTimeMillis();
for (int i = 0; i < 500000; i++) {
sbi.setLength(0);
}
long s11 = System.currentTimeMillis();
System.out.println("StringBuffer-setLength:" + (s11 - s1)); s1 = System.currentTimeMillis();
for (int i = 0; i < 500000; i++) {
sbf.delete(0, sbf.length());
}
s11 = System.currentTimeMillis();
System.out.println("StringBuffer--delete:" + (s11 - s1));
s1 = System.currentTimeMillis();
for (int i = 0; i < 500000; i++) {
sbf = new StringBuffer("");
}
s11 = System.currentTimeMillis();
System.out.println("StringBuffer--new StringBuffer:" + (s11 - s1));
}
|
測試結果:
| 1 2 3 |
StringBuffer-setLength:63
StringBuffer--delete:109
StringBuffer--new StringBuffer:78
|
測試結論:
要通過使用sbi.setLength(0);來清空StringBuffer對象中的內容效率最高
StringBuffer 清空