1、使用for循环打印输出99乘法表，如下图所示。
public class Test {
public static void main(String[] args) {
for(int i = 1;i <= 9;i++) {
for(int j = 1;j <= i;j++) {
System.out.print(i + "*" + j + "=" + i*j + "\t");
}
System.out.println();
}
}
}
2、使用for循环打印输出三角形
public class Test {
public static void main(String[] args) {
//正三角
for(int i = 1;i <= 5;i++) {
for(int j = 1;j <= i;j++) {
System.out.print("* ");
}
System.out.println();
}
//倒三角
for(int i = 6;i >= 1;i--) {
for(int j = 1;j <= i;j++) {
System.out.print("* ");
}
System.out.println();
}
}
}
3、使用for循环打印输出菱形
public class Test {
public static void main(String[] args) {
for (int i = 6; i >= 1;i--) {
for (int j = 1;j < i;j++) {
System.out.print(" ");
}
for (int k = 1;k <= 7-i; k++){
System.out.print("* ");
}
System.out.println();
}
for (int i = 1; i <= 6; i++) {
for (int j = 1; j <= i; j++) {
System.out.print(" ");
}
for (int k = 6-i; k >= 1; k--) {
System.out.print("* ");
}
System.out.println();
}
}
}
4、使用for循环打印输出圆形
public class Round {
public static void main(String[] args) {
int r = 10; //半径
for (int y = 0; y <= 2 * r; y += 2) {
long x = Math.round(r - Math.sqrt(2 * r * y - y * y));
long longLength = 2 * (r - x);
for (int i = 0; i <= x; i++) {
System.out.print(' ');
}
System.out.print('*');
for (int j = 0; j <= longLength; j++) {
System.out.print(' ');
}
System.out.println('*');
}
}
}
