JAVA.CLASS.CAST.ARRSTORE : Risky array store (Java)

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JAVA.CLASS.CAST.ARRSTORE : Risky array store (Java)

Summary

The value written into an array cannot be assigned to the type of the elements of the array.

Store operations into arrays might fail at runtime if the type of the elements of the array cannot hold the value written into the array. This situation can arise if an API provides public methods for setting an array and its elements, and those methods have permissive type signatures.

Java checks explicit type downcasts at runtime. If they do not hold, a runtime exception is thrown. This checker verifies that casts will be satisfied at runtime, so that they will never throw an exception.

Properties

Example

public class CheckArrays {
  private final Object[] arr;
  private int next;

  public CheckArrays(Object[] arr) {
    this.arr = arr;
  }

  public void add(Object o) {
    if (next < arr.length)
      arr[next++] = o; // "Risky array store (Java)" warning issued here
  }

  public static void main(String[] args) {
    CheckArrays ca = new CheckArrays(new String[5]);
    ca.add(new Object());
  }
}

Resolution

For each classcast warning, verify that all types that will ever reach that program point are assignable to the type used for the cast.

Relevant Configuration File Parameters

The following configuration file parameters affect checks for this warning class.