String 字符串处理

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public class StringConcatTest extends TestCase{public static int COUNT = 100000 ;public  void testString() {String result = "";long start = System.currentTimeMillis();for (int i = 0; i < COUNT; i++) {result = result + i;}long end = System.currentTimeMillis();System.out.println("用 + 耗时：\t" + (end - start));String result1 = "";start = System.currentTimeMillis();for (int i = 0; i < COUNT; i++) {result1 = result1.concat(String.valueOf(i));}end = System.currentTimeMillis();System.out.println("用 concat 耗时：\t"+(end - start));start = System.currentTimeMillis();StringBuffer buffer = new StringBuffer();for (int i = 0; i < 10000; i++) {buffer.append(i);}end = System.currentTimeMillis();System.out.println("用 StringBuffer 耗时：\t"+(end - start));start = System.currentTimeMillis();StringBuilder sb = new StringBuilder();for (int i = 0; i < 10000; i++) {sb.append(i);}end = System.currentTimeMillis();System.out.println("用 StringBuilder 耗时：\t"+(end - start));}}

测试结果

用 + 耗时：17517用 concat 耗时：8813用 StringBuffer 耗时：1用 StringBuilder 耗时：0

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