未报告的异常 java.lang.Exception; 必须被捕获或声明被抛出
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Unreported exception java.lang.Exception; must be caught or declared to be thrown
提问by pee2pee
I tried compiling the below but get the following around m16h(x):
我尝试编译以下内容，但在 m16h(x) 附近得到以下内容：
Line: 16
unreported exception java.lang.Exception; must be caught or declared to be thrown
Not sure why though. I've tried various things but it seems I am doing it right.
不知道为什么。我尝试了各种方法，但似乎我做得对。
import java.math.BigInteger;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;
public class Test{
public static void main(String args[]){
byte[] k1 = parseHexString("eb35a6c92c3b8c98033d739969fcc1f5ee08549e", 20);
byte[] k2 = parseHexString("57cb8b13a1f654de21104c551c13d8820b4d6de3", 20);
byte[] k3 = parseHexString("c4c4df2f8ad3683677f9667d789f94c7cffb5f39", 20);
System.out.println(k1);
System.out.println(k2);
System.out.println(k3);
System.out.println(xor(m16h(add(xor(xor(m16h(add(k1, m16h(add(k2, m16h(k3))))), k3), k2), k1)), k3));
}
public static byte[] m16h(byte[] m) throws Exception {
return parseHexString(SHA1(m), 20);
}
private static byte[] xor(byte[] x, byte[] y) {
int l = x.length;
if (l != y.length) {
return null;
}
byte[] ob = new byte[l];
for (int i = 0; i < l; i++) {
ob[i] = (byte) (x[i] ^ y[i]);
}
return ob;
}
public static byte[] parseHexString(String x, int len) {
byte[] ret = new byte[len];
for (int i = 0; i < len; i++) {
ret[i] = (byte) Integer.parseInt(x.substring(i * 2, (i * 2) + 2), 16);
}
return ret;
}
public static byte[] add(byte[] x, byte[] y) {
byte[] added = new byte[(x.length + y.length)];
System.arraycopy(x, 0, added, 0, x.length);
System.arraycopy(y, 0, added, x.length, y.length);
return added;
}
public static String SHA1(byte[] c) throws NoSuchAlgorithmException {
return base16encode(MessageDigest.getInstance("SHA-1").digest(c));
}
public static String base16encode(byte[] data) {
String res = "";
for (byte b : data) {
res = String.format("%s%02x", new Object[]{res, Byte.valueOf(b)});
}
return res;
}
}
采纳答案by Yassin Hajaj
public static byte[] m16h(byte[] m) throws Exception
public static byte[] m16h(byte[] m) throws Exception
The signature of your method indicates that an Exception is susceptible of being thrown.
你的方法的签名表明一个异常容易被抛出。
This means that the exception either :
这意味着异常要么：
Must be handled by the caller
try { System.out.println(xor(m16h(add(xor(xor(m16h(add(k1, m16h(add(k2, m16h(k3))))), k3), k2), k1)), k3)); } catch (Exception e) { e.printStackTrace(); }Must be rethrowed by the caller
public static void main(String[] args) throws Exception
必须由调用者处理
try { System.out.println(xor(m16h(add(xor(xor(m16h(add(k1, m16h(add(k2, m16h(k3))))), k3), k2), k1)), k3)); } catch (Exception e) { e.printStackTrace(); }必须由调用者重新抛出
public static void main(String[] args) throws Exception
回答by christophetd
In your main method, the call to m16hmay lead to an exception being thrown. In this case, you have two choices:
在您的 main 方法中，对 的调用m16h可能会导致抛出异常。在这种情况下，您有两个选择：
- handle the exception yourself in the main method.
- 在 main 方法中自己处理异常。
// in the main
try {
System.out.println(xor(m16h(...));
} catch(Exception e) {
// do something, e.g. print e.getMessage()
}
- indicate that the main method can throw an exception, by appending
throws Exceptionto its declaration.
- 通过附加
throws Exception到它的声明，表明 main 方法可以抛出异常。
public static void main(String args[]) throws Exception
public static void main(String args[]) throws Exception
回答by SCouto
Surround the line where you call this method with a try/catch block as follows:
使用 try/catch 块包围您调用此方法的行，如下所示：
try {
System.out.println(xor(m16h(add(xor(xor(m16h(add(k1, m16h(add(k2, m16h(k3))))), k3), k2), k1)), k3));
}catch (Exception e){
System.out.println (e.getMessage());
}
