常见异常举例

运行时异常：

1、空指针异常

package 异常处理;

import org.junit.Test;

public class ExceptionTest {
//NullPointerException空指针异常
	@Test
	public void test1(){
		int[] arr=null;
		System.out.println(arr[3]);
	}
}

package 异常处理;

import org.junit.Test;

public class ExceptionTest {
//NullPointerException空指针异常
	@Test
	public void test1(){
//		int[] arr=null;
//		System.out.println(arr[3]);
		String str=null;
		System.out.println(str.charAt(0));
//charAt（）：输出第X个字符
	}
}

2、数组角标越界

package 异常处理;

import org.junit.Test;

public class ExceptionTest {
//NullPointerException空指针异常
	@Test
	public void test2() {
//		int[] arr=null;
//		System.out.println(arr[3]);
//		String str=null;
//		System.out.println(str.charAt(0));
		int[] arr = new int[10];
		System.out.println(arr[10]);
	}
}

3、两个类型间转换不兼容：ClassCastException

package 异常处理;

import java.util.Date;

import org.junit.Test;

public class ExceptionTest {
	// ClassCastException
	@Test
	public void test3() {
		Object obj = new Date();
		String str1 = (String) obj;

	}
}

4、NumberFormatException

package 异常处理;

import java.util.Date;

import org.junit.Test;

public class ExceptionTest {
	// NumberFormatException
	@Test
	public void test4() {
		String str1 = "123";
		str1 = "abc";
		int num = Integer.parseInt(str1);

	}
}

5、InputMismatchException

package 异常处理;

import java.util.Scanner;

import org.junit.Test;

public class ExceptionTest {
	// NumberFormatException
	@Test
	public void test5() {
		Scanner scanner = new Scanner(System.in);
		int score = scanner.nextInt();
		System.out.println(score);

	}
}

6、ArithmeticException:算术异常

package 异常处理;

import java.util.Scanner;

import org.junit.Test;

public class ExceptionTest {
	// ArithmeticException
	@Test
	public void test5() {
		int a = 10;
		int b = 0;
		System.out.println(a / b);
	}
}

二、编译时异常

略....