01.Java基础

学习笔记

数组

一维数组

int[] nums=new int[10];
int[] nums={1,2,3};

二维数组

int[][] array=new int[2][3];
int[][] array={{1,2,3},{2,3,4};
// 打印二维数组
 for (int[] ints:a){
            for (int anint:ints){
                System.out.print(anint+" ");
            }
            System.out.println();
        }

Arrays类

//打印数组元素
System.out.println(Arrays.toString(nums));
Arrays.sort(nums);
//填充
Arrays.fill(num,1);

异常

throw和throws

//throw：主动抛出异常在方法中使用
throw new ArithmeticException();
//throws:假设这个方法中，处理不了这个异常。在方法上抛出异常
 public void test()throws ArithmeticException{}

自定义异常

//自定义异常类，继承Exception
public class MyException extends Exception {
    private int detail;
    public MyException(int a) {
        this.detail=a;
    }

    @Override
    public String toString() {
        return "MyException{" +
                "detail=" + detail +
                '}';
    }
}
// 测试类
public class Test {
    public static void main(String[] args) {
        try {
            test(11);
        } catch (MyException e) {
            System.out.println("MyException"+e);
        }

    }

    static void test(int a) throws MyException {
        if (a>10){
            throw new MyException(a);
        }
        System.out.println("OK");
    }
}