blocks|key|2501898|text|当您在循环中找不到结果时，您就缺少了一个return。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|2501899|protected+Node+getTrueParent()+{
++++for+(Edge+e+:+this.edges)+{
++++++++if+(e.getNode2()+==+this+&&+(!e.isPseudo()))+{
++++++++++++Node+parent+=+e.getNode1();
++++++++++++return+parent;
++++++++}
++++}
++++return+null;+//+ADD+THIS
}|code-block|syntax|javascript|2501900|如果您确信这不应该发生，并且您认为这里不应该有返回，那么抛出一个例外：|2501901|protected+Node+getTrueParent()+{
++++for+(Edge+e+:+this.edges)+{
++++++++if+(e.getNode2()+==+this+&&+(!e.isPseudo()))+{
++++++++++++Node+parent+=+e.getNode1();
++++++++++++return+parent;
++++++++}
++++}
++++throw+new+IllegalStateException("Somebody+broke+the+data.+Send+Help!");
}|2501902|entityMap^0|K|6|0|0|0|0^^$0|@$1|2|3|4|5|6|7|Q|8|@$9|R|A|S|B|C]]|D|@]|E|$]]|$1|F|3|G|5|H|7|T|8|@]|D|@]|E|$I|J]]|$1|K|3|L|5|6|7|U|8|@]|D|@]|E|$]]|$1|M|3|N|5|H|7|V|8|@]|D|@]|E|$I|J]]|$1|O|3|-4|5|6|7|W|8|@]|D|@]|E|$]]]|P|$]]

You're missing a <code>return</code> when you're not finding the result in the loop.

<pre><code>protected Node getTrueParent() {
 for (Edge e : this.edges) {
 if (e.getNode2() == this &amp;&amp; (!e.isPseudo())) {
 Node parent = e.getNode1();
 return parent;
 }
 }
 return null; // ADD THIS
}
</code></pre>

If you're absolutely sure this shouldn't happen and you think there shouldn't be a return here, throw an exception:

<pre><code>protected Node getTrueParent() {
 for (Edge e : this.edges) {
 if (e.getNode2() == this &amp;&amp; (!e.isPseudo())) {
 Node parent = e.getNode1();
 return parent;
 }
 }
 throw new IllegalStateException("Somebody broke the data. Send Help!");
}
</code></pre>

blocks|key|2980366|text|如果循环结束而不返回任何内容，则必须返回某些内容。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|2980367|例如：|2980368|protected+Node+getTrueParent()+{
++++for+(Edge+e+:+this.edges)+{
++++++++if+(e.getNode2()+==+this+&&+(!e.isPseudo()))+{
++++++++++++return+e.getNode1();
++++++++}
++++}
++++return+null;
}|code-block|syntax|javascript|2980369|entityMap^0|0|0|0^^$0|@$1|2|3|4|5|6|7|K|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|L|8|@]|9|@]|A|$]]|$1|D|3|E|5|F|7|M|8|@]|9|@]|A|$G|H]]|$1|I|3|-4|5|6|7|N|8|@]|9|@]|A|$]]]|J|$]]

You must return something if the loop ends without returning anything.

For example :

<pre><code>protected Node getTrueParent() {
 for (Edge e : this.edges) {
 if (e.getNode2() == this &amp;&amp; (!e.isPseudo())) {
 return e.getNode1();
 }
 }
 return null;
}
</code></pre>

blocks|key|2501954|text|如果e.getNode2()永远不是this，它会返回什么？整个方法的所有路径都必须返回某些内容。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|2501955|entityMap^0|2|C|I|4|0^^$0|@$1|2|3|4|5|6|7|H|8|@$9|I|A|J|B|C]|$9|K|A|L|B|C]]|D|@]|E|$]]|$1|F|3|-4|5|6|7|M|8|@]|D|@]|E|$]]]|G|$]]

What will it return if <code>e.getNode2()</code> is never <code>this</code>? All paths throughout the method must end up returning something.

blocks|key|2501961|text|bcz在if条件下封装了返回，因此编译器正在抱怨。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|2501962|按以下方式更改代码|2501963|++++protected+Node+getTrueParent()+{
++++++++for+(Edge+e+:+this.edges)+{
++++++++++++if+(e.getNode2()+==+this+&&+(!e.isPseudo()))+{
++++++++++++++++Node+parent+=+e.getNode1();
++++++++++++++++return+parent;
++++++++++++}

++++++++}
++++++++++return+null;
++++}|code-block|syntax|javascript|2501964|entityMap^0|0|0|0^^$0|@$1|2|3|4|5|6|7|K|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|L|8|@]|9|@]|A|$]]|$1|D|3|E|5|F|7|M|8|@]|9|@]|A|$G|H]]|$1|I|3|-4|5|6|7|N|8|@]|9|@]|A|$]]]|J|$]]

bcz you have wrapped the return in the if condition and hence the compiler is complaining.

Change your code as below

<pre><code> protected Node getTrueParent() {
 for (Edge e : this.edges) {
 if (e.getNode2() == this &amp;&amp; (!e.isPseudo())) {
 Node parent = e.getNode1();
 return parent;
 }

 }
 return null;
 }
</code></pre>

blocks|key|2980419|text|如果if语句没有实现，您忘了返回！|type|unstyled|depth|inlineStyleRanges|entityRanges|data|2980420|protected+Node+getTrueParent()+{
++++for+(Edge+e+:+this.edges)+{
++++++++if+(e.getNode2()+==+this+&&+(!e.isPseudo()))+{
++++++++++++Node+parent+=+e.getNode1();
++++++++++++return+parent;
++++++++}
++++}
++++return+null;+//+if+you+dont+find+something
}|code-block|syntax|javascript|2980421|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

You forgot to return if the if statement does not come true!

<pre><code>protected Node getTrueParent() {
 for (Edge e : this.edges) {
 if (e.getNode2() == this &amp;&amp; (!e.isPseudo())) {
 Node parent = e.getNode1();
 return parent;
 }
 }
 return null; // if you dont find something
}
</code></pre>

blocks|key|2502013|text|您的Node类应该对Edge列表进行空检查。此外，您应该为实例字段提供访问器/变体器。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|2502014|import+java.util.List;

public+class+Node+{
++++private+List<Edge>+edges+=+null;

++++public+List<Edge>+getEdges()+{
++++++++return+edges;
++++}

++++public+void+setEdges(List<Edge>+edges)+{
++++++++this.edges+=+edges;
++++}

++++protected+Node+getTrueParent()+{
++++++++if+(getEdges()+!=+null+&&+!getEdges().isEmpty())+{
++++++++++++for+(Edge+e+:+getEdges())+{
++++++++++++++++if+(e+!=+null+&&+e.getNode2()+==+this+&&+!e.isPseudo())+{
++++++++++++++++++++return+e.getNode1();
++++++++++++++++}
++++++++++++}
++++++++}
++++++++return+null;
++++}
}|code-block|syntax|javascript|2502015|entityMap^0|2|4|A|4|0|0^^$0|@$1|2|3|4|5|6|7|M|8|@$9|N|A|O|B|C]|$9|P|A|Q|B|C]]|D|@]|E|$]]|$1|F|3|G|5|H|7|R|8|@]|D|@]|E|$I|J]]|$1|K|3|-4|5|6|7|S|8|@]|D|@]|E|$]]]|L|$]]

Your <code>Node</code> class should have null-checks for your <code>Edge</code> list. Also, you should provide accessors/mutators for your instance fields.

<pre><code>import java.util.List;

public class Node {
 private List&lt;Edge&gt; edges = null;

 public List&lt;Edge&gt; getEdges() {
 return edges;
 }

 public void setEdges(List&lt;Edge&gt; edges) {
 this.edges = edges;
 }

 protected Node getTrueParent() {
 if (getEdges() != null &amp;&amp; !getEdges().isEmpty()) {
 for (Edge e : getEdges()) {
 if (e != null &amp;&amp; e.getNode2() == this &amp;&amp; !e.isPseudo()) {
 return e.getNode1();
 }
 }
 }
 return null;
 }
}
</code></pre>

blocks|key|2980486|text|protected+Node+getTrueParent()+{
++++Node+parent=null;
++++for+(Edge+e+:+this.edges)+{
++++++++if+(e.getNode2()+==+this+&&+(!e.isPseudo()))+{
++++++++++++Node+parent+=+e.getNode1();
++++++++++++return+parent;
++++++++}
++++}
++++return+parent;
}|type|code-block|depth|inlineStyleRanges|entityRanges|data|syntax|javascript|2980487|unstyled|entityMap^0|0^^$0|@$1|2|3|4|5|6|7|G|8|@]|9|@]|A|$B|C]]|$1|D|3|-4|5|E|7|H|8|@]|9|@]|A|$]]]|F|$]]

<pre><code>protected Node getTrueParent() {
 Node parent=null;
 for (Edge e : this.edges) {
 if (e.getNode2() == this &amp;&amp; (!e.isPseudo())) {
 Node parent = e.getNode1();
 return parent;
 }
 }
 return parent;
}
</code></pre>

When coding in Python, I often use to break functions/methods by inserting <code>return</code> within loops, for example when a condition has been reached and I want to return the value. I noticed that if I do this in Java, the IDE (in this case Eclipse) doesn't seem to recognize the <code>return</code> command. For example here:

<pre><code>protected Node getTrueParent() {
 for (Edge e : this.edges) {
 if (e.getNode2() == this &amp;&amp; (!e.isPseudo())) {
 Node parent = e.getNode1();
 return parent;
 }
 }
}
</code></pre>

Eclipse points out that "This method must return a result of type Node".
Is it wrong what I am doing? Also, <code>parent</code> is declared within the <code>for</code> loop, so I cannot return it outside of the loop. One way would be to declare <code>parent</code> at the beginning (i.e. outside of the loop), but this would be quite sloppy for me to read. What is a proper way to write this?

Return inside a loop: wrong in Java?

翻译质量差，导致语言生硬或混乱。

没有提供实际的解决方法或示例。

解答不清晰，无法理解或解决问题。

页面排版不美观，阅读体验差。

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在用Python编写代码时，我经常通过在循环中插入return来中断函数/方法，例如，当达到条件时，我想返回值。我注意到，如果我在Java中这样做，IDE (在本例中是Eclipse)似乎不识别return命令。例如，在这里：protected Node getTrueParent() {    for (Edge e...

问返回循环: Java中的错误吗？
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