Example

protected void finalize() throws Throwable {
try {
System.out.println("finalize was called"); //$NON-NLS-1$
} finally {
super .finalize();
}
}

public static void main(String[] args){
ExplicitFinalize_Exemplo ef = new ExplicitFinalize_Exemplo();
try {
ef.finalize();
}catch (Throwable th){
th.printStackTrace();
}
}

Solução
Evite chamar o finalize() explicitamente

protected void finalize() throws Throwable {
try {
System.out.println("finalize was called"); //$NON-NLS-1$
} finally {
super .finalize();
}
}

public static void main(String[] args){
ExplicitFinalize_Solution ef = new ExplicitFinalize_Solution();
}