java基础知识点05_异常

java基础知识点05_异常

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异常的超类：java.lang.Throwable

异常处理机制

捕获：

int a = 1;
int b = 0;
try {
	System.out.println(a/b);
} catch (ArithmeticException e) {
	System.out.println("程序出现异常：变量b不能为0");
}finally {
	System.out.println("finally....");
}

public static void main(String[] args) {
	try {
		a();
	} catch (*Error e) {
		System.out.println("程序出现错误：*Error");
	}finally {
		System.out.println("finally....");
	}
}
	
public static void a() {
	b();
}
	
public static void b() {
	a();
}

抛出：

• 系统自动抛出：

public static void main(String[] args) {
	System.out.println(1/0);
}

Exception in thread "main" java.lang.ArithmeticException: / by zero

• 开发者主动抛出：

public static void main(String[] args) {
	int a = 1;
	int b = 0;
	if(b==0) {
		throw new ArithmeticException();
	}else {
		System.out.println(a/b);
	}	
}

Exception in thread "main" java.lang.ArithmeticException

自定义异常：

public class MyException extends Exception{
	
	//传递数字，如果数字大于10，则抛出异常
	private int detail;

	public MyException(int a) {
		this.detail = a;
	}
	
	@Override
	public String toString() {
		return "MyException{"
				+ "detail=}"
				+ detail
				+ "}";
	}
	
}


public class demo01 {

	static void test(int a) throws MyException {
		if(a>10) {
			throw new MyException(a);
		}
		System.out.println("okkkkkkkkkkk");
	}
	
	public static void main(String[] args) {
		try {
			test(23);
		} catch (MyException e) {
			System.out.println(e);
			e.printStackTrace();
		}
	}
}