代码之家 › 专栏 › 技术社区 › Cheok Yan Cheng

计算分配对象所需的内存

java

Cheok Yan Cheng · 技术社区 · 15 年前

// How much memory required to allocate 100 Calendar objects?
for (int i = 0; i < 100; i++) {
    Calendar c = Calendar.getInstance();
    l = l + c.getTimeInMillis();
    CalendarList.add(c);
}

// How much memory required to allocate Joda TimeDate objects?
for (int i = 0; i < 100; i++) {
    DateTime dateTime = new DateTime();
    l = l + dateTime.getMillis();
    DateTimeList.add(dateTime);
}

我能知道我能加上什么代码来衡量吗?

3 回复 | 直到 15 年前

user85421 15 年前

使用检测获取内存使用提示:

public class MemUsage {

    public static void main(String[] args) {
        Instrumentation instr = InstrumentationAgent.getInstrumentation();
        if (instr == null) {
            System.err.println("No Instrumentation, use the VM option \"-javaagent:Instrumentation.jar\"");
            return;
        }
        System.out.println();
        System.out.println("an implementation-specific approximation of the amount of storage");
        System.out.println("Calendar = " + instr.getObjectSize(Calendar.getInstance()));
        System.out.println();
    }
}

其他选择: MemoryMXBean 但我从没用过。