StringConcatenate.java 文件

public class StringConcatenate {public static void main(String[] args){long startTime = System.currentTimeMillis();for(int i=0;i<5000;i++){String result = "This is"+ "testing the"+ "difference"+ "between"+ "String"+ "and"+ "StringBuffer";}long endTime = System.currentTimeMillis();System.out.println("字符串连接" + " - 使用 + 操作符 : " + (endTime - startTime)+ " ms");long startTime1 = System.currentTimeMillis();for(int i=0;i<5000;i++){StringBuffer result = new StringBuffer();result.append("This is");result.append("testing the");result.append("difference");result.append("between");result.append("String");result.append("and");result.append("StringBuffer");}long endTime1 = System.currentTimeMillis();System.out.println("字符串连接" + " - 使用 StringBuffer : "+ (endTime1 - startTime1)+ " ms");}
}

字符串连接 - 使用 + 操作符 : 0 ms
字符串连接 - 使用 StringBuffer : 6 ms

public class StringConcatenate {public static void main(String[] args){long startTime = System.currentTimeMillis();String[] strArr = new String[500];for(int i=0;i<500;i++){String result = "This is";strArr[i]=String.valueOf(result.hashCode());}long endTime = System.currentTimeMillis();System.out.println("字符串连接" + " - 使用 + 操作符 : " + (endTime - startTime)+ " ms");System.out.println(strArr[0]+"\n"+strArr[1]+"\n"+strArr[2]);long startTime1 = System.currentTimeMillis();for(int i=0;i<500;i++){StringBuffer result = new StringBuffer();result.append("This is");strArr[i]=String.valueOf(result.hashCode());}long endTime1 = System.currentTimeMillis();System.out.println("字符串连接" + " - 使用 StringBuffer : "+ (endTime1 - startTime1)+ " ms");System.out.println(strArr[0]+"\n"+strArr[1]+"\n"+strArr[2]);}
}

字符串连接-使用+操作符：1ms
-1027042079
-1027042079
-1027042079
字符串连接-使用StringBuffer操作符：2ms1167165921
1442002549
1383884648

result =result +  "This is esting the difference between String and StringBuffer ";
或
result.append("This is esting the difference between String and StringBuffer" );

public class Main {public static void main(String[] args){String result1 = null;StringBuffer result = new StringBuffer();long startTime = System.currentTimeMillis();for(int i=0;i<5000;i++){result1 += "This is"+ "testing the"+ "difference"+ "between"+ "String"+ "and"+ "StringBuffer";}long endTime = System.currentTimeMillis();System.out.println("字符串连接" + " - 使用 + 操作符 : " + (endTime - startTime)+ " ms");long startTime1 = System.currentTimeMillis();for(int i=0;i<5000;i++){result.append("This is");result.append("testing the");result.append("difference");result.append("between");result.append("String");result.append("and");result.append("StringBuffer");}long endTime1 = System.currentTimeMillis();System.out.println("字符串连接" + " - 使用 StringBuffer : "+ (endTime1 - startTime1)+ " ms");}
}

字符串连接 - 使用 + 操作符 : 1151 ms
字符串连接 - 使用 StringBuffer : 2 ms