unchecked

问题 My program compiles fine, but my console spits out the following: ----jGRASP exec: javac -g CreditGraphics.java Note: CreditGraphics.java uses unchecked or unsafe operations. Note: Recompile with -Xlint:unchecked for details. ----jGRASP: operation complete. First, what makes an operation unsafe? And how can a process be "unchecked"? What does "Recompile with -Xlint" mean? I'm using jGrasp and I'm not sure if that's a button or some sort of command? I want to see the details. It doesn't

问题 I have a datagridview that is databound. How can I cancel the checkbox being checked in the datagridview if some condition is not met? private void dataGridViewStu_CellContentClick(object sender, DataGridViewCellEventArgs e) { dataGridViewStu.CommitEdit(DataGridViewDataErrorContexts.Commit); } private void dataGridViewStu_CellValueChanged(object sender, DataGridViewCellEventArgs e) { } 回答1: One possible way is to handle the CurrentCellDirtyStateChanged event on DataGridView . Check your

问题 What is the difference between checked(a + b) and unchecked(a + b) ? 回答1: Those are operators that check (or do not check) for overflow in the resulting numerical operation. In the checked case, an OverflowException exception is raised if the result of the operation exceeds the minimum or maximum value allowed for the datatype. More information is available from MSDN. 回答2: It controls overflow checking for integer operations. 回答3: if a + b is larger than the maximum value of the datatype,

问题 What is the difference between checked(a + b) and unchecked(a + b) ? 回答1: Those are operators that check (or do not check) for overflow in the resulting numerical operation. In the checked case, an OverflowException exception is raised if the result of the operation exceeds the minimum or maximum value allowed for the datatype. More information is available from MSDN. 回答2: It controls overflow checking for integer operations. 回答3: if a + b is larger than the maximum value of the datatype,

问题 I have a legacy webapp which uses jstl and Struts 1 tags. When I pre-compile the JSP files with Java 5/6, the jstl and Struts 1 tags throw warnings about "unchecked or unsafe operations". For example, if I use the following tag: <%@ page import="/anotherpage.inc" %> The following warning is thrown: [javac] Note: Some input files use unchecked or unsafe operations. [javac] Note: Recompile with -Xlint:unchecked for details. If I recompile with -Xlint:unchecked, I get details about the internal

问题 This is a Trying to improve my code question. About generics and the unchecked warning; I do know about the @suppresswarnings annotation. The question is what am I suppose to code to suppress it . Take, please, the following code. public class NumericBox<T extends Number> implements Box<T> { private T element; public NumericBox(T element) { this.element = element; } @Override public T getElement() { return element; } public T insert(Number newElement) { T oldElement = this.element; this

问题 int y = -2147483648; int z = unchecked(y / -1); The second line causes an OverflowException . Shouldn't unchecked prevent this? For example: int y = -2147483648; int z = unchecked(y * 2); doesn't cause an exception. 回答1: This is not an exception that the C# compiler or the jitter have any control over. It is specific to Intel/AMD processors, the CPU generates a #DE trap (Divide Error) when the IDIV instruction fails. The operating system handles the processor trap and reflects it back into

问题 int y = -2147483648; int z = unchecked(y / -1); The second line causes an OverflowException . Shouldn't unchecked prevent this? For example: int y = -2147483648; int z = unchecked(y * 2); doesn't cause an exception. 回答1: This is not an exception that the C# compiler or the jitter have any control over. It is specific to Intel/AMD processors, the CPU generates a #DE trap (Divide Error) when the IDIV instruction fails. The operating system handles the processor trap and reflects it back into

问题 here is part of tutorial in oracle page : Consider the following example: List l = new ArrayList<Number>(); List<String> ls = l; // unchecked warning l.add(0, new Integer(42)); // another unchecked warning String s = ls.get(0); // ClassCastException is thrown In detail, a heap pollution situation occurs when the List object l, whose static type is List<Number> , is assigned to another List object, ls, that has a different static type, List<String> // this is from oracle tutorial my question

问题 I'm trying to implement a sorted list as a simple exercise in Java. To make it generic I have an add(Comparable obj) so I can use it with any class that implements the Comparable interface. But, when I use obj.compareTo(...) anywhere in the code I get "unchecked call to compareTo(T) as a member of the raw type java.lang.Comparable" from the compiler (with -Xlint:unchecked option). The code works just fine but I can't figure out how to get rid of that annoying message. Any hints? 回答1: In