Java System.getProperty Missing Properties Guide

In Java, the method used to retrieve system properties is System.getProperty(). If there is a mistake while using this method, it could be due to one of the following reasons:

1. Incorrectly spelled property name: Make sure that the property name you pass to the System.getProperty() method is correct and matches the system property name exactly. Java system property names are case-sensitive.
2. If you try to retrieve a property that does not exist, the System.getProperty() method will return null. Make sure to check if the property exists before calling the System.getProperty() method.
3. Security restriction: In certain situations, the Java Virtual Machine may restrict access to certain system properties. This could be due to security settings or limitations in the runtime environment. Ensure that your application has sufficient permissions at runtime to access the necessary system properties.

When dealing with potential leaks, you can add appropriate error handling mechanisms to check if the returned value is null and take appropriate action when necessary. For example:

String propertyValue = System.getProperty("propertyName");
if (propertyValue != null) {
    // 处理属性值
} else {
    // 处理属性不存在的情况
}