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The method getAbsAdd() computes and returns the sum of the absolute value of parameters x and y. It lacks argument validation, in violation of rule MET00-J. Validate method arguments. Consequently, it can produce incorrect results because of integer overflow or when either or both of its arguments are Integer.MIN_VALUE.

public static int getAbsAdd(int x, int y) {
  return Math.abs(x) + Math.abs(y);
}
getAbsAdd(Integer.MIN_VALUE, 1);

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This noncompliant code example uses assertions to validate arguments of a public method.

public static int getAbsAdd(int x, int y) {
  assert x != Integer.MIN_VALUE;
  assert y != Integer.MIN_VALUE;
  int absX = Math.abs(x);
  int absY = Math.abs(y);
  assert (absX <= Integer.MAX_VALUE - absY);
  return absX + absY;
}

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This compliant solution validates the method arguments by ensuring that values passed to Math.abs() exclude Integer.MIN_VALUE and also by checking for integer overflow.

public static int getAbsAdd(int x, int y) {
  if (x == Integer.MIN_VALUE || y == Integer.MIN_VALUE) {
    throw new IllegalArgumentException();
  }
  int absX = Math.abs(x);
  int absY = Math.abs(y);
  if (absX > Integer.MAX_VALUE - absY) {
    throw new IllegalArgumentException();
  }
  return absX + absY;
}

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Android Implementation Details

The assert statement is supported on the Dalvik VM but is ignored under the default configuration. Assertions may be enabled by setting the system property "debug.assert" via: adb shell setprop debug.assert 1 or by sending the command line argument "--enable-assert" to the Dalvik VM.

Bibliography

      05. Methods (MET)