从列表中删除所有原因java.lang.UnsupportedOperationException(removeAll From a List Cause java.lang.UnsupportedO

从列表中删除所有原因java.lang.UnsupportedOperationException(removeAll From a List Cause java.lang.UnsupportedOperationException) java

我想将successList设置为[10,14]我试过的是，

String oneStr = "10,11,12,14"; String twoStr = "11,14"; Returns r = new Returns(); r.setFailureList(Arrays.asList(twoStr.split(","))); r.setSuccessList(Arrays.asList(oneStr.split(","))); r.getSuccessList().removeAll(r.getFailureList()); System.out.println(r.getSuccessList());

返回类是，

List<String> successList; List<String> failureList; public List<String> getSuccessList() { return successList; } public void setSuccessList(List<String> successList) { this.successList = successList; } public List<String> getFailureList() { return failureList; } public void setFailureList(List<String> failureList) { this.failureList = failureList; } public void setFailureList(ArrayList<String> failureList) { this.failureList = failureList; }

并且导致stackTrace的java.lang.UnsupportedOperationException ，

Exception in thread "main" java.lang.UnsupportedOperationException at java.util.AbstractList.remove(Unknown Source) at java.util.AbstractList$Itr.remove(Unknown Source) at java.util.AbstractCollection.removeAll(Unknown Source)

I want to set successList as [10,14] What i tried is,

String oneStr = "10,11,12,14"; String twoStr = "11,14"; Returns r = new Returns(); r.setFailureList(Arrays.asList(twoStr.split(","))); r.setSuccessList(Arrays.asList(oneStr.split(","))); r.getSuccessList().removeAll(r.getFailureList()); System.out.println(r.getSuccessList());

The Returns Class is,

List<String> successList; List<String> failureList; public List<String> getSuccessList() { return successList; } public void setSuccessList(List<String> successList) { this.successList = successList; } public List<String> getFailureList() { return failureList; } public void setFailureList(List<String> failureList) { this.failureList = failureList; } public void setFailureList(ArrayList<String> failureList) { this.failureList = failureList; }

And Cause java.lang.UnsupportedOperationException the stackTrace is,

Exception in thread "main" java.lang.UnsupportedOperationException at java.util.AbstractList.remove(Unknown Source) at java.util.AbstractList$Itr.remove(Unknown Source) at java.util.AbstractCollection.removeAll(Unknown Source)

最满意答案

来自asList（）的文档

返回由指定数组支持的固定大小的列表。

因此，当您直接修改（添加，删除..etc）时，您最终会遇到exception 。

所以，但在这种情况下

new ArrayList<String>(Arrays.asList(twoStr.split(",")))

在这里，您不是直接引用该list 。 您正在创建一个新的ArrayList并使用Arrays.as.asList(twoStr.split(","))返回的列表数据，这不是Unmodifiable （就大小而言）。

From docs of asList()

Returns a fixed-size list backed by the specified array.

So when you are directly modifying(adding, removing ..etc) to that, you end up with exception.

So , but in the case

new ArrayList<String>(Arrays.asList(twoStr.split(",")))

Here you are not referring to the list directly. You are creating a new ArrayList and using the data of the list returned by Arrays.as.asList(twoStr.split(",")) ,which is not a Unmodifiable(in terms of size).