java中获取hashmap中的所有key方式

import java.util.HashMap;
import java.util.Set;

public class Test {
    /**
     * 使用递归反转字符串
     */
    public static void main(String[] args) {

        //先创建一个hashmap
        HashMap<String, Integer> map = new HashMap<>();
        map.put("张三", 65);
        map.put("李四", 84);
        map.put("王五", 75);
        map.put("王二麻子", 85);
        //获取所有的可以值
        Set<String> keySet = map.keySet();
        //遍历
        for (String key : keySet) {
            System.out.println(key);
        }
    }
}

        public final int hashCode() {
            return Objects.hashCode(key) ^ Objects.hashCode(value);
        }

public int hashCode() {
	return J9VMInternals.fastIdentityHashCode(this);
}

	static int fastIdentityHashCode(Object anObject) {
		com.ibm.jit.JITHelpers h = jitHelpers;
		if (null == h) {
			return identityHashCode(anObject); /* use early returns to make the JIT code faster */
		}
		if (h.is32Bit()) {
			int ptr = h.getIntFromObject(anObject, 0L);
			if ((ptr & com.ibm.oti.vm.VM.OBJECT_HEADER_HAS_BEEN_MOVED_IN_CLASS) != 0) {
				if (!h.isArray(anObject)) {
					int j9class = ptr & com.ibm.oti.vm.VM.J9_JAVA_CLASS_MASK;
					return h.getIntFromObject(anObject, h.getBackfillOffsetFromJ9Class32(j9class));
				}
			}
		} else {
			long ptr = (com.ibm.oti.vm.VM.FJ9OBJECT_SIZE == 4) ? Integer.toUnsignedLong(h.getIntFromObject(anObject, 0L)) : h.getLongFromObject(anObject, 0L);
			if ((ptr & com.ibm.oti.vm.VM.OBJECT_HEADER_HAS_BEEN_MOVED_IN_CLASS) != 0) {
				if (!h.isArray(anObject)) {
					long j9class = ptr & com.ibm.oti.vm.VM.J9_JAVA_CLASS_MASK;
					return h.getIntFromObject(anObject, h.getBackfillOffsetFromJ9Class64(j9class));
				}
			}
		}
		return identityHashCode(anObject);
	}