public class ExceptionTest{
    //NullPointerException
    @Test
    public void test1(){
        int[] arr = null;
        System.out.println(arr[3]);
        str = null;
        System.out.println(str.charAt(0));
    }
    //IndexOutOfBoundsException
    @Test
    public void test2(){
        //ArrayIndexOutOfBoundsException
        int[] arr = new int[10];
        System.out.println(arr[10]);
        //StringIndexOutOfBoundsException
        str = "abc";
        System.out.println(str.charAt(3));
    }
    //ClassCastException：類型不匹配
    @Test
    public void test3(){
        Object obj = new Date();
        String str = (String)obj;
    }
    //NumberFormatException:數(shù)據(jù)格式異常
    @Test
    public void test4(){
        str = "abc";
        int num = Integer.parseInt(str);
    }
    //InputMismatchException:輸入不匹配異常
    @Test
    public void test5(){
        Scanner scanner = new Scanner(System.in);
        int score = scanner.nextInt();
        System.out.println(score);
    }
    //ArithmeticException:算數(shù)異常
    @Test
    public void test6(){
        int a = 10;
        int b= 0;
        System.out.println(a\b);
    }
}

try{
    //可能出現(xiàn)異常的代碼
}catch(異常類型1 變量名1){//一段代碼可能有多個(gè)異常類型
    //處理異常的方式1
}catch(異常類型2 變量名2){
    //處理異常的方式2
}catch(異常類型3 變量名3){
    //處理異常的方式3
}
.....
finally{
    //一定會(huì)執(zhí)行的代碼
}

    @Test
	public void test1() {
		str = "abc";
		int num = 0;// 聲明放在外面，出了try,還可以使用num;
        //但是此時(shí)要注意：在try-catch結(jié)構(gòu)中，num不一定被賦值，所以要手動(dòng)的給賦默認(rèn)初始化值
		try {
			num = Integer.parseInt(str);
		} catch (NullPointerException e) {
			System.out.println(e.getMessage());
		} catch (NumberFormatException e) {
			e.printStackTrace();
		}
		System.out.println(num);
	}

@Test//catch中又出現(xiàn)異常了
public void test1(){
    try{
        int a = 10;
        int b = 0;
        System.out.println(a / b);
    }catch(ArithmeticException e){
        int[] arr = new int[10];
        System.out.println(arr[10]);
    }
        //System.out.println("catch中又出現(xiàn)異常了，但我一定不會(huì)輸出！");
    finally{
        System.out.println("catch中又出現(xiàn)異常了，但我一定會(huì)輸出！");
    }
}

@Test//try中有return語(yǔ)句、catch中有return語(yǔ)句
public void testMethod(){
    int num = method();
}
public int method(){
    try{
        int[] arr = new int[10];
        System.out.println("arr[10]");
        return 1;
    }catch(ArrayIndexOutOfBoundException e){
        e.printStockTrace();
        return 2;
    }finally{
        System.out.println("我一定會(huì)被執(zhí)行！");
        return 3;
    }
}
//finally中一定會(huì)執(zhí)行的結(jié)構(gòu)在執(zhí)行順序上優(yōu)于try、catch中的return語(yǔ)句
//由于方法只能有一個(gè)返回值，所以最后返回的是return 3;

public class ExceptionTest2 {
	public static void main(String[] args) {
		try {
			method2();
		} catch (FileNotFoundException e) {
			e.printStackTrace();
		} catch (IOException e) {
			e.printStackTrace();
		}
		method3();// 在method2()里已經(jīng)解決了異常，所以可以調(diào)用
	}
	public static void method3() {
		try {
			method2();
		} catch (IOException e) {
			e.printStackTrace();
		}
	}
	public static void method2() throws FileNotFoundException, IOException {
		method1();
	}
	public static void method1() throws FileNotFoundException, IOException {//異常代碼
		File file = new File("hello.txt");
		FileInputStream fis = new FileInputStream(file);
		int data = fis.read();
		while (data != -1) {
			System.out.print((char) data);
			data = fis.read();
		}
		fis.close();
		System.out.println("hanhan");// 不會(huì)被執(zhí)行！
	}
}

public class StudentTest {
	public static void main(String[] args) {
		Student s = new Student();
		s.regist(-1001);
		System.out.println(s);
	}
}
class Student {
	private int id;
	public void regist(int id) {
		if (id > 0) {
			this.id = id;
		} else {//方式一：拋出運(yùn)行時(shí)異常，運(yùn)行時(shí)會(huì)報(bào)錯(cuò)
			// 手動(dòng)拋出異常對(duì)象
			throw new RuntimeException("您輸入的數(shù)據(jù)非法！");
		}
	}
}

public class StudentTest {
	public static void main(String[] args) {
		try {
			Student s = new Student();
			s.regist(-1001);
			System.out.println(s);
		} catch (Exception e) {
			System.out.println(e.getMessage());
		}
	}
}
class Student {
	private int id;
	public void regist(int id) throws Exception {//throws:體現(xiàn)異常的處理
		if (id > 0) {
			this.id = id;
		} else {//拋出編譯時(shí)異常：必須顯式的處理
			throw new Exception("您輸入的數(shù)據(jù)非法！");//throw:體現(xiàn)生成一個(gè)異常對(duì)象
		}
	}
}

public class StudentTest {
	public static void main(String[] args) {
		try {
			Student s = new Student();
			s.regist(-1001);
			System.out.println(s);
		} catch (Exception e) {
			System.out.println(e.getMessage());
		}
	}
}
class Student {
	private int id;
	public void regist(int id) throws Exception {
		if (id > 0) {
			this.id = id;
		} else {
			throw new MyException("不能輸入負(fù)數(shù)");//自定義異常類的使用
		}
	}
}
public class MyException extends RuntimeException {//自定義異常類
	static final long serialVersionUID = -7034897190745766939L;
	public MyException() {
	}
	public MyException(String msg) {
		super(msg);
	}
}