我有一个包含私人对象列表的类。
private List<Object> mylist;
此外，我的课程包含两种方法：
（1） addObject
public void addObject(Object obj)
{
this.mylist.add(obj);
}
（2） dropObject
dropObject有点棘手。我想将mylist中与信号obj相等（但不相同）的第一个元素删除。因此，我将参数obj的类与mylist中的每个元素的类进行比较。如果当前元素的类匹配，我想比较两个元素是否相等（但不相同）。
这里我有一些比较数组的问题。我想使用Array.deepEquals()，这需要对obj和curr_obj进行类型转换。
所以这是我的代码：
public void dropArgument(Object obj) {
if (obj == null) {
return;
}
Object objRemove = null;
for (Object curr_obj : this.mylist) {
if (curr_obj.getClass() != obj.getClass()) {
continue;
}
// primitive data type comparison
if (obj.getClass().isPrimitive() && curr_obj == obj) {
objRemove = curr_obj;
}
// array comparison
else if ((obj.getClass().isArray())
/* the following line gives me headache */
&& (Arrays.deepEquals((Object[]) curr_obj, (Object[]) obj))) {
objRemove = curr_obj;
}
// wrapper / collection comparison
else if (curr_obj.equals(obj)) {
objRemove = curr_obj;
}
// comparison of any other classes which are assumed not to have an 'equals' method.
else {
Field[] fInputFields = obj.getClass().getDeclaredFields();
Field[] fFields = curr_obj.getClass().getDeclaredFields();
if (Arrays.deepEquals(fInputFields, fFields)) {
objRemove = curr_obj;
}
}
}
// delete obj match if found
if (objRemove != null) {
this.mylist.remove(objRemove);
}
}
我为这个方法编写了测试，并且每种类型的数组得到以下内容（int []数组的stackstrace）：
error:
java.lang.ClassCastException: [I cannot be cast to [Ljava.lang.Object;
at javafxTablePane.FieldMethodData.dropArgument(FieldMethodData.java:119)
at tests.DropArgumentsTests.test_dropMultiArrayInteger(DropArgumentsTests.java:345)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:498)
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.runners.ParentRunner.runLeaf(ParentRunner.java:325)
at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:78)
at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:57)
at org.junit.runners.ParentRunner$3.run(ParentRunner.java:290)
at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:71)
at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:288)
at org.junit.runners.ParentRunner.access$000(ParentRunner.java:58)
at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:268)
at org.junit.runners.ParentRunner.run(ParentRunner.java:363)
at org.eclipse.jdt.internal.junit4.runner.JUnit4TestReference.run(JUnit4TestReference.java:86)
at org.eclipse.jdt.internal.junit.runner.TestExecution.run(TestExecution.java:38)
at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:459)
at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:678)
at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.run(RemoteTestRunner.java:382)
at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.main(RemoteTestRunner.java:192)
错误很明显：int[]不能被Object[]类型化。所以我的问题是，由于Array.deepEquals()需要类型转换，我如何将对象重新转换为它们自己的类/数据类型作为数组？
我搜索了这个，发现getClass().getComponentType()方法提供了我的对象的数组类型。但我不知道（如果可能的话）如何使用它来将obj强制转换为自己的数组类型。
其他一些信息：
Object obj作为我的方法的参数，以便能够获得独立于类或数据类型的任何对象。我遵循了Darshan Mehta的建议并实现了一个简单的方法，将1维数组从原始类转换为包装类。我可以继续开发更通用的代码（例如，任何维度的数组），因此这个解决方案适合我的问题。我把我的代码放在这里给那些感兴趣的人。
/**
* <b>ArrayEquals</b>
* <p>
* Compares two arrays of any same class and delivers their equality as boolean.
* </p>
*
* @param obj1
* [Object] : any object of any class as Object
* @param obj2
* [Object] : any object of the same class as obj1 as Object
* @return [boolean] : Equality of obj1 and obj2
*/
private boolean ArrayEquals(Object obj1, Object obj2) {
Class<?> cObj1 = obj1.getClass().getComponentType();
// convert byte[] to Byte[]
if (cObj1.equals(byte.class)) {
byte[] tmpObj1 = (byte[]) obj1;
byte[] tmpObj2 = (byte[]) obj2;
if (tmpObj1.length != tmpObj2.length) {
return false;
}
Byte[] newObj1 = new Byte[tmpObj1.length];
Byte[] newObj2 = new Byte[tmpObj2.length];
for (int i = 0; i < tmpObj1.length; i++) {
newObj1[i] = tmpObj1[i]; // Autoboxing
newObj2[i] = tmpObj2[i]; // Autoboxing
}
return Arrays.deepEquals(newObj1, newObj2);
}
// convert short[] to Short[]
else if (cObj1.equals(short.class)) {
short[] tmpObj1 = (short[]) obj1;
short[] tmpObj2 = (short[]) obj2;
if (tmpObj1.length != tmpObj2.length) {
return false;
}
Short[] newObj1 = new Short[tmpObj1.length];
Short[] newObj2 = new Short[tmpObj2.length];
for (int i = 0; i < tmpObj1.length; i++) {
newObj1[i] = tmpObj1[i]; // Autoboxing
newObj2[i] = tmpObj2[i]; // Autoboxing
}
return Arrays.deepEquals(newObj1, newObj2);
}
// convert int[] to Integer[]
else if (cObj1.equals(int.class)) {
Integer[] newObj1 = Arrays.stream((int[]) obj1).boxed().toArray(Integer[]::new);
Integer[] newObj2 = Arrays.stream((int[]) obj2).boxed().toArray(Integer[]::new);
return Arrays.deepEquals(newObj1, newObj2);
}
// convert long[] to Long[]
else if (cObj1.equals(long.class)) {
Long[] newObj1 = Arrays.stream((long[]) obj1).boxed().toArray(Long[]::new);
Long[] newObj2 = Arrays.stream((long[]) obj2).boxed().toArray(Long[]::new);
return Arrays.deepEquals(newObj1, newObj2);
}
// convert float[] to Float[]
else if (cObj1.equals(float.class)) {
float[] tmpObj1 = (float[]) obj1;
float[] tmpObj2 = (float[]) obj2;
if (tmpObj1.length != tmpObj2.length) {
return false;
}
Float[] newObj1 = new Float[tmpObj1.length];
Float[] newObj2 = new Float[tmpObj2.length];
for (int i = 0; i < tmpObj1.length; i++) {
newObj1[i] = tmpObj1[i]; // Autoboxing
newObj2[i] = tmpObj2[i]; // Autoboxing
}
return Arrays.deepEquals(newObj1, newObj2);
}
// convert double[] to Double[]
else if (cObj1.equals(double.class)) {
double[] tmpObj1 = (double[]) obj1;
double[] tmpObj2 = (double[]) obj2;
if (tmpObj1.length != tmpObj2.length) {
return false;
}
Double[] newObj1 = new Double[tmpObj1.length];
Double[] newObj2 = new Double[tmpObj2.length];
for (int i = 0; i < tmpObj1.length; i++) {
newObj1[i] = tmpObj1[i]; // Autoboxing
newObj2[i] = tmpObj2[i]; // Autoboxing
}
return Arrays.deepEquals(newObj1, newObj2);
}
// convert boolean[] to Boolean[]
else if (cObj1.equals(boolean.class)) {
boolean[] tmpObj1 = (boolean[]) obj1;
boolean[] tmpObj2 = (boolean[]) obj2;
if (tmpObj1.length != tmpObj2.length) {
return false;
}
Boolean[] newObj1 = new Boolean[tmpObj1.length];
Boolean[] newObj2 = new Boolean[tmpObj2.length];
for (int i = 0; i < tmpObj1.length; i++) {
newObj1[i] = tmpObj1[i]; // Autoboxing
newObj2[i] = tmpObj2[i]; // Autoboxing
}
return Arrays.deepEquals(newObj1, newObj2);
}
// convert char[] to Character[]
else if (cObj1.equals(char.class)) {
char[] tmpObj1 = (char[]) obj1;
char[] tmpObj2 = (char[]) obj2;
if (tmpObj1.length != tmpObj2.length) {
return false;
}
Character[] newObj1 = new Character[tmpObj1.length];
Character[] newObj2 = new Character[tmpObj2.length];
for (int i = 0; i < tmpObj1.length; i++) {
newObj1[i] = tmpObj1[i]; // Autoboxing
newObj2[i] = tmpObj2[i]; // Autoboxing
}
return Arrays.deepEquals(newObj1, newObj2);
}
// is no primitive
else {
return Arrays.deepEquals((Object[]) obj1, (Object[]) obj2);
}
}
答案 0 :(得分：3)
在比较两个对象时，您应该执行以下操作：
private boolean equals(Object o1, Object o2)，并使用dropObject方法调用）。array.getClass().getComponentType()方法调用获取组件类型，并尝试将其强制转换为适当的数组。将int数组转换为Object数组将抛出ClassCastException。有关强制转换和数组类型的更多说明，请参阅this SO答案。equals方法。