Detailed analysis of return values at different positions in Java exception handling scenarios

Xiaojiang 2100 2021-01-23 19:40:20
detailed analysis return values different


Java The return values in exception handling are different in different situations , We need to pay more attention here

There are two scenarios :

  • 1 finally Statement block does not have return sentence , That is, when the code is executed to try perhaps catch In statement block return When the sentence is , It is equivalent to saving a local copy of the value of the variable that returns the value at this time , And then according to try catch finally To execute finally Sentence block , Then go back and return the copy data you just saved to

The first example is in try There is no exception in , Go straight to try In statement block return scene

public class Test01 {
public static void main(String[] args) {
int results=new Test01().test(10,2);
System.out.println("func results:"+results);
}
public int test(int a,int b)
{
int results=0;
try
{
System.out.println("in try.....");
results+=1;
System.out.println("results = "+results);
return results;
}
catch (Exception e)
{
System.out.println("in catch......");
results+=1;
System.out.println("results = "+results);
return results;
}
finally {
System.out.println("in finally");
results+=1;
System.out.println("results = "+results);
}
}
}

The results are as follows , The last value returned by the function is 1, instead of 2

in try.....
results = 1
in finally
results = 2
func results:1

The second example is try There's an exception in , But in catch I'm here in the middle return sentence

public class Test01 {
public static void main(String[] args) {
int results=new Test01().test(10,2);
System.out.println("func results:"+results);
}
public int test(int a,int b)
{
int results=0;
try
{
System.out.println("in try.....");
results+=1;
System.out.println("results = "+results);
double d=1/0;
return results;
}
catch (Exception e)
{
System.out.println("in catch......");
results+=1;
System.out.println("results = "+results);
return results;
}
finally {
System.out.println("in finally");
results+=1;
System.out.println("results = "+results);
}
}
}

The return value is as follows , That is to say, the return value is 2 instead of 3

in try.....
results = 1
in catch......
results = 2
in finally
results = 3
func results:2
  • 2 finally The statement block has return sentence , At this point, I finally return to finally The value in the statement block , and try perhaps catch There is... In the statement block return sentence , And it won't work

The following example is try I can walk to return sentence , Again finally There are also return At the time of the statement , Return at this time finally In statement block return Value

public class Test01 {
public static void main(String[] args) {
int results=new Test01().test(10,2);
System.out.println("func results:"+results);
}
public int test(int a,int b)
{
int results=0;
try
{
System.out.println("in try.....");
results+=1;
System.out.println("results = "+results);
return results;
}
catch (Exception e)
{
System.out.println("in catch......");
results+=1;
System.out.println("results = "+results);
return results;
}
finally {
System.out.println("in finally");
results+=1;
System.out.println("results = "+results);
return results;
}
}
}

The results are as follows , return 2, This is not a return 1 了

in try.....
results = 1
in finally
results = 2
func results:2

The following example is in catch Go to the return sentence , Also in finally In the statement block, we also come to return sentence , This is also a return finally The value in the statement block ,catch Invalid return value in statement block

public class Test01 {
public static void main(String[] args) {
int results=new Test01().test(10,2);
System.out.println("func results:"+results);
}
public int test(int a,int b)
{
int results=0;
try
{
System.out.println("in try.....");
results+=1;
System.out.println("results = "+results);
double d=1/0;
return results;
}
catch (Exception e)
{
System.out.println("in catch......");
results+=1;
System.out.println("results = "+results);
return results;
}
finally {
System.out.println("in finally");
results+=1;
System.out.println("results = "+results);
return results;
}
}
}

The results are as follows : return 3 instead of 2 了

in try.....
results = 1
in catch......
results = 2
in finally
results = 3
func results:3
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本文为[Xiaojiang 2100]所创,转载请带上原文链接,感谢
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