Java 中的可抛出 initCause()方法，示例
原文:https://www . geesforgeks . org/throwable-init cause-method-in-Java-with-examples/
可抛出类的 initCause() 方法用于初始化该可抛出的原因，指定的原因作为参数传递给 initCause()。实际上，原因是当异常发生时，引发这个可抛出对象的可抛出性。此方法只能调用一次。通常，此方法在构造函数中调用，或者在创建可抛出的之后立即调用。如果调用 Throwable 是通过使用 Throwable(Throwable)或 Throwable(String，Throwable)创建的，那么这个方法甚至不能被调用一次。
语法:
public Throwable initCause?(Throwable cause)
参数:该方法接受原因作为代表该可投掷原因的参数。
返回:这个方法返回对这个可抛出实例的引用。
异常:此法抛出:
- IllegalArgumentException If this is the cause, it can be thrown.
- illegal state exception If this Throwable is created by throwable or throwable (String, throwable), or this method has been called on this throwable.
下面的程序说明了可抛出类的 initCause 方法:
例 1:
// Java program to demonstrate
// the initCause() Method.
import java.io.*;
class GFG {
// Main Method
public static void main(String[] args)
throws Exception
{
try {
testException1();
}
catch (Throwable e) {
System.out.println("Cause : "
+ e.getCause());
}
}
// method which throws Exception
public static void testException1()
throws Exception
{
// ArrayIndexOutOfBoundsException Exception
// This exception will be used as a Cause
// of another exception
ArrayIndexOutOfBoundsException
ae
= new ArrayIndexOutOfBoundsException();
// create a new Exception
Exception ioe = new Exception();
// initialize the cause and throw Exception
ioe.initCause(ae);
throw ioe;
}
}
输出:
Cause : java.lang.ArrayIndexOutOfBoundsException
例 2:
// Java program to demonstrate
// the initCause() Method.
import java.io.*;
class GFG {
// Main Method
public static void main(String[] args)
throws Exception
{
try {
// add the numbers
addPositiveNumbers(2, -1);
}
catch (Throwable e) {
System.out.println("Cause : "
+ e.getCause());
}
}
// method which adds two positive number
public static void addPositiveNumbers(int a, int b)
throws Exception
{
// if Numbers are Positive
// than add or throw Exception
if (a < 0 || b < 0) {
// create a Exception
// when Numbers are not Positive
// This exception will be used as a Cause
// of another exception
Exception
ee
= new Exception("Numbers are not Positive");
// create a new Exception
Exception anotherEXe = new Exception();
// initialize the cause and throw Exception
anotherEXe.initCause(ee);
throw anotherEXe;
}
else {
System.out.println(a + b);
}
}
}
输出:
Cause : java.lang.Exception: Numbers are not Positive
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