import org.checkerframework.checker.nullness.qual.*;
import org.checkerframework.checker.nullness.qual.EnsuresNonNull;
import org.checkerframework.checker.nullness.qual.EnsuresNonNullIf;

public class AssertWithStatic {

  static @Nullable String f;

  @EnsuresNonNullIf(result = true, expression = "AssertWithStatic.f")
  public boolean hasSysOut1() {
    return AssertWithStatic.f != null;
  }

  @EnsuresNonNullIf(result = true, expression = "f")
  public boolean hasSysOut2() {
    return AssertWithStatic.f != null;
  }

  @EnsuresNonNullIf(result = true, expression = "AssertWithStatic.f")
  public boolean hasSysOut3() {
    return f != null;
  }

  @EnsuresNonNullIf(result = true, expression = "f")
  public boolean hasSysOut4() {
    return f != null;
  }

  @EnsuresNonNullIf(result = false, expression = "AssertWithStatic.f")
  public boolean noSysOut1() {
    return AssertWithStatic.f == null;
  }

  @EnsuresNonNullIf(result = false, expression = "f")
  public boolean noSysOut2() {
    return AssertWithStatic.f == null;
  }

  @EnsuresNonNullIf(result = false, expression = "AssertWithStatic.f")
  public boolean noSysOut3() {
    return f == null;
  }

  @EnsuresNonNullIf(result = false, expression = "f")
  public boolean noSysOut4() {
    return f == null;
  }

  @EnsuresNonNull("AssertWithStatic.f")
  // :: error: (contracts.postcondition)
  public void sysOutAfter1() {}

  @EnsuresNonNull("f")
  // :: error: (contracts.postcondition)
  public void sysOutAfter2() {}
}