private List<String> values = new ArrayList<String>();
public WhitespaceEqualsTest() {
values.add("I ");
values.add("I");
values.add(". ");
values.add(".");
values.add("1");
values.add("1 ");
System.out.println(refine(values));
}
private List<String> refine(List<String> input){
ArrayList<String> outerLoopValues = (ArrayList<String>) input;
ArrayList<String> innerLoopValues = (ArrayList<String>) input;
ArrayList<String> results = new ArrayList<String>();
for(String string1 : outerLoopValues){
for(String string2 : innerLoopValues){
if(string1.contains(string2) == false){
results.add(string1);
}
}
}
Set<String> temp = new HashSet<String>();
temp.addAll(results);
results.clear();
results.addAll(temp);
return results;
}
@Override
public int hashCode() {
final int prime = 31;
int result = 1;
result = prime * result + ((values == null) ? 0 : values.hashCode());
return result;
}
@Override
public boolean equals(Object obj) {
if (this == obj)
return true;
if (obj == null)
return false;
if (getClass() != obj.getClass())
return false;
WhitespaceEqualsTest other = (WhitespaceEqualsTest) obj;
if (values == null) {
if (other.values != null)
return false;
} else if (!values.equals(other.values))
return false;
return true;
}
我已经覆盖了hashCode()
和equals()
,因此我不确定错误是什么。它们是使用Eclipse生成的(Source - &gt; Generate hashCode()和equals())。为什么没有检测到没有空格的相同字符包含在带空格的字符中?输出是:
[1, . , I , I, ., 1 ]
答案 0 :(得分:0)
正如其中一条评论中所提到的,您应该使用String包装器来包装字符串并覆盖equals和hashcode方法。
我的解决方案基于"I "
应该等于"I"
的假设,因此只应将其中一个添加到结果中。
但是我需要根据Java Objects中的文档添加
和Java Arraylist分别涉及equals
和contains
。 hashcode
方法必须返回一个公共值。我在代码中写了解释为注释。如果有任何问题,请告诉我。
主类
public class StackOverflowMain
{
private static List<String> values = new ArrayList<String>();
public static void main(String[] args) {
values.add("I ");
values.add("I");
values.add(". ");
values.add(".");
values.add("1");
values.add("1 ");
List<WhitespaceEqualsTest> toRefineList = new ArrayList<WhitespaceEqualsTest>();
for (String value : values) {
toRefineList.add(new WhitespaceEqualsTest(value));
}
System.out.println(refine(toRefineList));
}
private static List<WhitespaceEqualsTest> refine(List<WhitespaceEqualsTest> input) {
ArrayList<WhitespaceEqualsTest> loopValues = (ArrayList<WhitespaceEqualsTest>) input;
ArrayList<WhitespaceEqualsTest> results = new ArrayList<WhitespaceEqualsTest>();
for (WhitespaceEqualsTest value : loopValues) {
if (!results.contains(loopValues)) {
results.add(value);
}
}
Set<WhitespaceEqualsTest> temp = new HashSet<WhitespaceEqualsTest>();
temp.addAll(results);
results.clear();
results.addAll(temp);
return results;
}
}
内部WhitespaceEqualsTest
类
class WhitespaceEqualsTest {
private String value;
public WhitespaceEqualsTest(String value) {
this.value = value;
}
public void setString(String value) {
this.value = value;
}
public String getString() {
return this.value;
}
public int hashCode() {
/*
* Arraylist.contains is evaluated by using (o==null ? e==null : o.equals(e)) as mentioned in the javadoc
* and Object.equals() would evaluate using hashcode() first to check if the object o is equal to object e
* before calling .equals() method to evaluate.
*
* As mentioned in java doc at http://docs.oracle.com/javase/7/docs/api/java/util/Collection.html#equals(java.lang.Object)
* c1.equals(c2) implies that c1.hashCode()==c2.hashCode() should be satisfied
* which is not in this question
*/
return 0;
}
@Override
public boolean equals(Object obj) {
if (this == obj)
return true;
if (obj == null)
return false;
if (getClass() != obj.getClass())
return false;
WhitespaceEqualsTest other = (WhitespaceEqualsTest) obj;
if (value == null) {
if (other.value != null)
return false;
} else if (!value.contains(other.value) && !other.value.contains(value)){
/*
* Does a checking on both ends since "I " contains "I" but "I" does not contain "I " due to the whitespace
* For this question, if one of the condition satisfy it should be equal
*/
return false;
}
return true;
}
@Override
public String toString() {
return this.value;
}
}
结果
[I , . , 1]
答案 1 :(得分:0)
String类是final。所以你不能覆盖它的equals和hashCode方法。
private List<StringWrapper> values = new ArrayList<StringWrapper>();
public WhitespaceEqualsTest() {
values.add(new StringWrapper("I "));
values.add(new StringWrapper("I"));
values.add(new StringWrapper(". "));
values.add(new StringWrapper("."));
values.add(new StringWrapper("1"));
values.add(new StringWrapper("1 "));
System.out.println(refine(values));
}
private List<StringWrapper> refine(List<StringWrapper> input){
//no need to iterate the list
//the set will automatically cancel out the duplicate
Set<StringWrapper> temp = new HashSet<StringWrapper>(input);
ArrayList<StringWrapper> results = new ArrayList<StringWrapper>();
results.addAll(temp);
return results;
}
创建一个String的包装类,然后重写equals和hashcode方法。
class StringWrapper {
private String value;
public StringWrapper(String value){
this.value = value;
}
public String getValue() {
return value;
}
public void setValue(String value) {
this.value = value;
}
@Override
public String toString(){
return value;
}
@Override
public boolean equals(Object obj){
boolean result = Boolean.FALSE;
if(obj != null && obj instanceof StringWrapper){
StringWrapper stringWrapper = (StringWrapper) obj;
result = value.trim().equals(stringWrapper.getValue().trim());
}
return result;
}
@Override
public int hashCode() {
final int prime = 31;
int result = 1;
result = prime * result + ((value.trim() == null) ? 0 : value.trim().hashCode());
return result;
}
}
答案 2 :(得分:-1)
您将值添加到Set。在任何情况下,Set都会出现一次值 - 因此它是一个集合。 ;)
您也可以修改循环以查看发生的情况
for(String string1 : outerLoopValues){
for(String string2 : innerLoopValues){
if(string1.contains(string2) == false){
results.add(string1);
System.out.println("added \"" + string1 + "\" since it does not contain \"" + string2 + "\"");
}
}
}
提供以下输出:
added "I " since it does not contain ". "
added "I " since it does not contain "."
added "I " since it does not contain "1"
added "I " since it does not contain "1 "
added "I" since it does not contain "I "
added "I" since it does not contain ". "
added "I" since it does not contain "."
added "I" since it does not contain "1"
added "I" since it does not contain "1 "
......
[1, . , I , I, ., 1 ]
如果他们不相互包含它们是我想的想法吗?
然后通过Set推送List删除重复项!见这里:Does adding a duplicate value to a HashSet/HashMap replace the previous value
将循环中的条件从false更改为true会产生此结果(在最后一行输出中使用Set / HashSet后没有变化!)
added "I " since it does contain "I "
added "I " since it does contain "I"
added "I" since it does contain "I"
added ". " since it does contain ". "
added ". " since it does contain "."
added "." since it does contain "."
added "1" since it does contain "1"
added "1 " since it does contain "1"
added "1 " since it does contain "1 "
[1, . , I , I, ., 1 ]
它回答了你的问题:它确实检测到了“我”包含“我”。
System.out.println("I ".contains("I"));
说“真实”
希望这有助于^^ - d