java 如何在try catch块之外访问变量
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how to access Variable outside a try catch block
提问by Ruman Khan Pathan
I'm trying to return a boolean valuefrom my function having try-catch block,
我正在尝试从具有try-catch 块的函数返回一个布尔值，
But the problem is I cant return any value.
但问题是我无法返回任何值。
I know that variable inside a try-catch block can't be accessed outside it but still I want to.
我知道 try-catch 块内的变量不能在它外部访问，但我仍然想要。
public boolean checkStatus(){
try{
InputStream fstream = MyRegDb.class.getClassLoader().getResourceAsStream("textfile.txt");
// Use DataInputStream to read binary NOT text.
BufferedReader br = new BufferedReader(new InputStreamReader(fstream));
String strLine;
//Read File Line By Line
strLine = br.readLine();
// Print the content on the console
System.out.println (strLine);
ind.close();
if(strLine.equals("1")){
return false;
}else{
return true;
}
}catch(Exception e){}
}
it's a super serious problem for me in my project. I googled, and tried myself, but nothing solved.
在我的项目中，这对我来说是一个非常严重的问题。我用谷歌搜索并尝试了自己，但没有解决。
I hope that now I will find some solution. I know that it has error saying return statement missingbut I want program exactly working like this.
我希望现在我能找到一些解决办法。我知道它有错误说缺少 return 语句，但我希望程序完全像这样工作。
Now the reason I'm strict to this
现在我对这个很严格的原因
In my jar file I have to access text files for finding values 1 or 0 if "1" then activate else deactivate.
在我的 jar 文件中，我必须访问文本文件以查找值 1 或 0 如果“1”然后激活否则停用。
that is why I am using Boolean.
这就是我使用布尔值的原因。
回答by Lucas
Just declare the boolean outside of the try/catch, and set the value in the try block
只需在 try/catch 之外声明布尔值，并在 try 块中设置值
public boolean myMethod() {
boolean success = false;
try {
doSomethingThatMightThrowAnException();
success = true;
}
catch ( Exception e ) {
e.printStackTrace();
}
return success;
}
回答by rgettman
In your method, if an Exceptionis thrown, then there is no return statement. Place a returnstatement either in the exception handler, in a finallyblock, or after the exception handler.
在您的方法中，如果Exception抛出an ，则没有 return 语句。将return语句放在异常处理程序中、finally块中或异常处理程序之后。
回答by Colin D
The error is that you are not returning anything in the case where an exception is thrown.
错误是在抛出异常的情况下您没有返回任何内容。
try the following:
尝试以下操作：
public boolean checkStatus(){
boolean result = true; // default value.
try{
InputStream fstream = MyRegDb.class.getClassLoader().getResourceAsStream("textfile.txt");
// Use DataInputStream to read binary NOT text.
BufferedReader br = new BufferedReader(new InputStreamReader(fstream));
String strLine;
//Read File Line By Line
strLine = br.readLine();
// Print the content on the console
System.out.println (strLine);
ind.close();
if(strLine.equals("1")){
result = false;
}else{
result = true;
}
}catch(Exception e){}
return result;
}
回答by Abhishek
Declare the String strLine brfore the try/catch block
and then write your if statement after the try/catch block like
在 try/catch 块之前声明 String strLine，然后在 try/catch 块
之后编写 if 语句，例如
String strLine;
try{
//......
}catch(Exception e){
//.....
}
if(strLine.equals("1"))
return false;
return true;
get rid of the else block.
摆脱 else 块。
回答by Prince Sharma
import java.io.*;
public class GameHelper
{
public String getUserInput(String prompt) {
String inputLine = null;
System.out.print(prompt + “ “);
try {
BufferedReader is = new BufferedReader(
new InputStreamReader(System.in));
inputLine = is.readLine();
if (inputLine.length() == 0 ) return null;
}
catch (IOException e) {
System.out.println(“IOException: “ + e);
}
return inputLine;
}
}
Make sure you write import java.io.*before you write your program. Now You will be able to return the function even outside the tryand catch
确保import java.io.*在编写程序之前先编写。现在您甚至可以在try和之外返回该函数catch
