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Private field is never initialized JAVA-E1065

Bug risk

This private field is never initialized before use. This may cause improper behavior at runtime, or even a NullPointerException.

Check if the logic that uses the field is correct; add an initializer to the declaration or initialize the field at an appropriate point before use.

If a field is not explicitly initialized, Java will set the value of the field to a default value at runtime. This default value depends on the type:

  • For primitives, it is 0 (or the floating point equivalent)
  • For descendants of Object, the default value is null.

Java does not check if a field is properly initialized in the way it checks local variables, and this can easily prevent one from immediately noticing that something is wrong.

Bad Practice

// Never initialized, never assigned a value.
private String internalField;

String someMethod() {
    someInternalCode(internalField); // `internalField` will be null!


Assign a valid default to the field, or initialize it wherever sensible.

private String internalField = "defaultValue";

// ...


This issue will not be reported for fields marked as being injected (marked with annotations such as @Inject or @Autowired).