1.

public class Text1 {
    public static void main(String[] args) {
        System.out.println("welcome java");
        System.out.println("hello world");
        System.out.println("hello javaee");
    }

}

2.

public class Text2 {
    public static void main(String[] args) {
        for(int i=1;i<=5;i++) {
            System.out.println("show your massage");
        }
    }
}

3.

public class Text3 {
    public static void main(String[] args) {
        System.out.println("    J     A     V       V      A");
        System.out.println("    J    A A      V    V     A  A");
        System.out.println("J   J   AAAAA      V V      AAAAAAA");
        System.out.println(" JJ    A     A      V      A       A");
    }
}

4.

public class Text4 {
    public static void main(String[] args) {
        System.out.println("a"+"\t"+"a^2"+"\t"+"a^3");
        System.out.println("1"+"\t"+"1"+"\t"+"1");
        System.out.println("2"+"\t"+"4"+"\t"+"8");
        System.out.println("3"+"\t"+"9"+"\t"+"27");
        System.out.println("4"+"\t"+"16"+"\t"+"64");
    }
}

5.

public class Text5 {
    public static void main(String[] args) {
        System.out.println("1+2+......+100的和为："+(101)*100/2);
    }
}

6.

import java.util.Scanner;

public class Text7 {
    public static void main(String[] args) {
        System.out.println("请输入圆的半径：");
        Scanner s=new Scanner(System.in);
        double r=s.nextDouble();
        double PI=3.14;
        double perimeter=r*2*PI;
        double are=r*r*PI;
        System.out.println("周长为："+perimeter+"面积为："+are);
    }
}

7.

public class Text9 {
    public static void main(String[] args) {
        double a=312032486;
        double day=365*24*60*60;
        System.out.println("第五年："+(a+(5*day)/7.0-(5*day)/13.0-(5*day)/45.0));
    }
}

8.

public class Text10 {
    public static void main(String[] args) {
        System.out.println("x的值为："+(44.5*0.55-50.2*5.9)/(3.4*0.55-50.2*2.1));
        System.out.println("y的值为："+(3.4*5.9-44.5*2.1)/(3.4*0.55-50.2*2.1));
    }
}