JDKJREJVM的关系

Posted 2021-03-21 haoyujun135

jdk    JAVA Development  Kit    java开发工具集
JRE   Java Runtime Environment  Java运行环境
Jvm   Java Virtual Machine        Java虚拟机
jdk = java语言+Tools +Tool APIs
Jre = Jvm + Java SE API + Deployment  （Java7版本Jvm在java se Api中）
Java SE API = Compact Profiles + User Interface Toolkits
User Interface Toolkits = lang and util Base Libraries + Other Base Libraries + Integration Libraries

Java API  java类库

 

 测试堆内存溢出代码：

1 public class Demo {
2 
3 }

 1 import java.util.ArrayList;
 2 import java.util.List;
 3 
 4 public class Test {
 5     public static void main(String[] args) {
 6         List<Demo> demoList = new ArrayList();
 7         while(true) {
 8             demoList.add(new Demo());
 9         }
10     }
11 }

错误：

1 Exception in thread "main" java.lang.OutOfMemoryError: Java heap space
2     at java.util.Arrays.copyOf(Arrays.java:3210)
3     at java.util.Arrays.copyOf(Arrays.java:3181)
4     at java.util.ArrayList.grow(ArrayList.java:261)
5     at java.util.ArrayList.ensureExplicitCapacity(ArrayList.java:235)
6     at java.util.ArrayList.ensureCapacityInternal(ArrayList.java:227)
7     at java.util.ArrayList.add(ArrayList.java:458)
8     at jvm.Test.main(Test.java:10)

给jvm传入参数  -XX:+HeapDumpOnOutOfMemoryError -Xms20m -Xmx20m   导出堆快照信息

错误：

java.lang.OutOfMemoryError: Java heap space
Dumping heap to java_pid19356.hprof ...
Heap dump file created [27964857 bytes in 0.107 secs]
Exception in thread "main" java.lang.OutOfMemoryError: Java heap space
    at java.util.Arrays.copyOf(Arrays.java:3210)
    at java.util.Arrays.copyOf(Arrays.java:3181)
    at java.util.ArrayList.grow(ArrayList.java:261)
    at java.util.ArrayList.ensureExplicitCapacity(ArrayList.java:235)
    at java.util.ArrayList.ensureCapacityInternal(ArrayList.java:227)
    at java.util.ArrayList.add(ArrayList.java:458)
    at jvm.Test.main(Test.java:10)

使用MemoryAnalyzer 工具分析堆内存情况