I am writing junit test for toArray method which is one of the method of ArrayBasedStack
. This class has an array inside and toArray method copies the element and return. The method is given by the class, and I amd trying to print out each element in the array.
This method copy the local array and return the copy array with the type of the Object.
public T[] toArray() {
T[] copy = (T[]) new Object[this.size()];
for (int i = 0; i < this.size(); i++) {
copy[i] = (T) this.myArray[i];
}
return copy;
}
For the test, I set up String array as like below:
private ArrayBasedStack stack;
public void setUp(){
stack = new ArrayBasedStack<String>();
}
To test toArray() method, I tried:
public void testToArray(){
stack.push("000");
stack.push("111");
assertEquals(2, stack.toArray().length);
assertEquals("111", stack.toArray()[0]);
}
Other than toArray() method, other methods' test passed well such as: peek()
, push()
, clear()
, equals()
... etc.
However, only this test returns error for both assertEquals
:
assertEquals(2, stack.toArray().length);
assertEquals("111", stack.toArray()[0]);
The error is:
>java.lang.ClassCastException: [Ljava.lang.Object; cannot be cast to [Ljava.lang.String;
at arraystack.ArrayBasedStackTest.testToArray(ArrayBasedStackTest.java:82)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
at java.lang.reflect.Method.invoke(Unknown Source)
at org.junit.runners.model.FrameworkMethod$1.runReflectiveCall(FrameworkMethod.java:50)
at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:12)
at org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:47)
at org.junit.internal.runners.statements.InvokeMethod.evaluate(InvokeMethod.java:17)
at org.junit.internal.runners.statements.RunBefores.evaluate(RunBefores.java:26)
at org.junit.internal.runners.statements.RunAfters.evaluate(RunAfters.java:27)
at org.junit.internal.runners.statements.FailOnTimeout$CallableStatement.call(FailOnTimeout.java:298)
at org.junit.internal.runners.statements.FailOnTimeout$CallableStatement.call(FailOnTimeout.java:292)
at java.util.concurrent.FutureTask.run(Unknown Source)
at java.lang.Thread.run(Unknown Source)