10个有关Java异常的最常见问题

try {
	File file = new File("path");
	FileInputStream fis = new FileInputStream(file);
	String s = "inside";
} catch (FileNotFoundException e) {
	e.printStackTrace();
	System.out.println(s);
}

Integer.parseInt(null); 
// throws java.lang.NumberFormatException: null
 
Double.parseDouble(null); 
// throws java.lang.NullPointerException

5. 常用的RuntimeException

IllegalArgumentException
ArrayIndexOutOfBoundsException

if (obj == null) {
   throw new IllegalArgumentException("obj can not be null");

6. 能在一个catch语句块中捕获多个异常吗？

class FileReader{
	public FileInputStream fis = null;
 
	public FileReader() throws IOException{
		File dir = new File(".");//get current directory
		File fin = new File(dir.getCanonicalPath() + File.separator + "not-existing-file.txt");
		fis = new FileInputStream(fin);
	}
}

public static void main(String[] args) {
	File file1 = new File("path1");
	File file2 = new File("path2");
	try {
 
		FileInputStream fis = new FileInputStream(file1);
	} catch (FileNotFoundException e) {
		e.printStackTrace();
	} finally {
		try {
			FileInputStream fis = new FileInputStream(file2);
		} catch (FileNotFoundException e) {
			e.printStackTrace();
		}
	}
}

public static void main(String[] args) {
	File file1 = new File("path1");
	File file2 = new File("path2");
	try {
 
		FileInputStream fis = new FileInputStream(file1);
	} catch (FileNotFoundException e) {
		e.printStackTrace();
	} finally {
		methodThrowException();
	}
}

9. finally 语句块中可以写return语句吗？

try {
     ...
} catch(Exception e) {
     e.printStackTrace();
}