public class SuanSu{
	public static void main(String args[]){
		int i1 = 7;
		int i2 = 3;
		int jia = i1 + i2;
		int jian = i1 - i2;
		int cheng = i1 * i2;
		int chu = i1 / i2;
		int yu = i1 % i2;
		
		System.out.println("进行加法运算得到的结果:"+jia);
		System.out.println("进行减法运算得到的结果:"+jian);
		System.out.println("进行乘法运算得到的结果:"+cheng);
		System.out.println("进行除法运算得到的结果:"+chu);
		System.out.println("进行余数运算得到的结果:"+yu);
	}
}

进行加法运算得到的结果:10
进行减法运算得到的结果:4
进行乘法运算得到的结果:21
进行除法运算得到的结果:2
进行余数运算得到的结果:1

public class SuanSu2{
	public static void main(String args[]){
		int i1 = 7;
		int i2 = 0;
		int chu = i1 / i2;
		int yu = i1 % i2;
		
		System.out.println("进行除法运算的结果是:"+chu);
		System.out.println("进行余数运算的结果是:"+yu);
	}
	
}

Exception in thread "main" java.lang.ArithmeticException: / by zero
	at SuanSu2.main(SuanSu2.java:5)

public class SuanSu3{
	public static void main(String args[]){
		String s1 = "Hello";
		String s2 = "World";
		
		String s3 = s1 + " " + s2;
		System.out.println(s3);
	}
}

Hello World