技術標籤：JVMjava

結論：不一樣的量級，結果不一樣。原因還在分析中，有直到的大拿幫忙回覆一下

package com.example.jvm;

import org.junit.Test;

/**
 * @Author jvm
 * @Date 2021/1/28 07:50
 * StringBuffer和StringBuilder效能測試
 * count:1W
 *  StringBufferExecutor: 7
 *  StringBuilderExecutor: 1
 * count:1KW
 *  StringBufferExecutor: 347
 *  StringBuilderExecutor: 357
 */
 

public class StringTest {
    int count = 10000000;
    @Test
    public void test() {
        executeCount(new StringBufferExecutor());
        executeCount(new StringBuilderExecutor());
    }

    void executeCount(Executor executor) {
        long cu = System.currentTimeMillis();
        for (int i = 0;
 
 i < count; i++) {
            executor.execute();
        }
        System.out.printf("%s: %d\n", executor.getClass().getSimpleName(), System.currentTimeMillis() - cu);
    }

    public interface Executor {
        void execute();
    }


    public static class StringBufferExecutor implements
 
 Executor {
        @Override
        public void execute() {
            StringBuffer sb = new StringBuffer();
            sb.append("1");
            sb.append("2");
        }
    }


    public static class StringBuilderExecutor implements Executor {
        @Override
        public void execute() {
            StringBuilder sb = new StringBuilder();
            sb.append("1");
            sb.append("2");
        }
    }
}