1.打印4层***
*****
*****
*****
*****class forfor{
public static void main(String[] args){
for(int y=0; y<4; y++){
for(int x=0; x<5; x++){
System.out.print("*");
}
System.out.println();
}
}
}2.打印5层*，每层递减
*****
****
***
**
*第一种方法：
class forfor{
public static void main(String[] args){
int z=0;
for(int y=0; y<5; y++){
for(int x=z; x<5; x++){
System.out.print("*");
}
System.out.println();
z++;
}
}
}第二种方法：
class forfor{
public static void main(String[] args) {
int z=5;
for (int y=0; y<5; y++) {
for (int x=z; x>0; x--) {
System.out.print("*");
}
System.out.println();
z--;
}
}
}第三种方法，推荐。
class forfor{
public static void main(String[] args){
for (int y=0; y<5; y++) {
for (int x=y; x<5; x++) {
System.out.print("*");
}
System.out.println();
}
}
}3.打印54321，每层递减
54321
5432
543
54
5class forfor{
public static void main(String[] args){
for (int y=0; y<5; y++) {
for (int x=5; x>y; x--) {
System.out.print(x);
}
System.out.println();
}
}
}4.打印12345，每层递增
1
22
333
4444
55555class forfor{
public static void main(String[] args){
for (int y=1; y<=5; y++) {
for (int x=1; x<=y; x++) {
System.out.print(y);
}
System.out.println();
}
}
}5.九九乘法表
1×1=1
1×2=2 2×2=4
1×3=3 2×3=6 3×3=9
1×4=4 2×4=8 3×4=12 4×4=16
1×5=5 2×5=10 3×5=15 4×5=20 5×5=25
1×6=6 2×6=12 3×6=18 4×6=24 5×6=30 6×6=36
1×7=7 2×7=14 3×7=21 4×7=28 5×7=35 6×7=42 7×7=49
1×8=8 2×8=16 3×8=24 4×8=32 5×8=40 6×8=48 7×8=56 8×8=64
1×9=9 2×9=18 3×9=27 4×9=36 5×9=45 6×9=54 7×9=63 8×9=72 9×9=81class forfor{
public static void main(String[] args){
for (int y=1; y<=9; y++) {
for (int x=1; x<=y; x++) {
System.out.print(x+"x"+y+"="+x*y+"\t");// \t:制表符
}
System.out.println();
}
}
}6.打印倒三角形
*******
*****
***
* class forfor{
public static void main(String[] args){
for (int y=1; y<=5; y++) {
for (int x=1; x<y; x++) {
System.out.print(" ");
}
for (int z=y; z<=5; z++) {
System.out.print("* ");
}
System.out.println();
}
}
}