Inverted half pyramid using numbers in JavaFX - javafx

Question

I made a normal half pyramid in JavaFX with this code
public void buttonpressed() {
int iNum = Integer.parseInt(Num.getText());
String sResult = "";
String sNumber = "";
for (int i = 1; i<=iNum; i++ ) {
sNumber += i;
sResult += sNumber + "\n";
result.setText(sResult);
}
}
Which outputs (if the inputted number was 5)
1
12
123
1234
12345
Now I have to make 2 triangles (one normal and one inverted) which would look like this (inputted number = 5)
1 12345
12 1234
123 123
1234 12
12345 1
The problem is that I don't understand how to make an inverted triangle, I found how to make one in Java
public class Main {
public static void main(String[] args) {
int rows = 5;
for (int i = rows; i >= 1; --i) {
for (int j = 1; j <= i; ++j) {
System.out.print(j + " ");
}
System.out.println();
}
}
}
But I can't adapt it to JavaFX so please help me with that.
I tried copying the for loops and adapting it to JavaFX but it didn't work.
public void buttonpressed() {
int iNum = Integer.parseInt(Num.getText());
String sResult = "";
String sNumber = "";
for (int i = inum3; i >= 1; i--) {
for (int j = 1; j <= i; ++j) {
sNumber+=j;
sResult += sNumber +"\n";
}
result.setText(sResult);
}
}
The result I want is
12345
1234
123
12
1
Instead, with the provided code, I get
1
12
123
1234
12345
123451
1234512
12345123
123451234
123451234123
1234512341231
12345123412312
123451234123121
The whole code is
package application;
import javafx.application.Application;
import javafx.scene.Scene;
import javafx.scene.control.Button;
import javafx.scene.control.Label;
import javafx.scene.control.TextField;
import javafx.scene.layout.GridPane;
import javafx.stage.Stage;
public class invertedtriangle extends Application{
TextField num = new TextField();
Label result = new Label();
public void start(Stage stage) {
GridPane p = new GridPane();
Scene scene = new Scene(p, 1000, 900);
Label input = new Label("Input a number");
Button press = new Button("Press");
p.add(input,0,1);
p.add(num, 0,2);
p.add(press, 0, 3);
p.add(result, 0, 4);
press.setOnAction(e -> buttonpressed());
p.setHgap(10.0);
p.setVgap(7.0);
stage.setTitle("inv triangle");
stage.setScene(scene);
stage.show();
}
public void buttonpressed() {
int iNum = Integer.parseInt(num.getText());
String sResult = "";
String sNumber = "";
for (int i = iNum; i >= 1; i--) {
for (int j = 1; j <= i; ++j) {
sNumber+=j;
sResult += sNumber +"\n";
}
result.setText(sResult);
}
}
public static void main(String[] args){
launch (args);
}
}

Answer 1

Just use the solution you already have, appending text to a string instead of sending it to the console:
public void buttonPressed() {
int iNum = Integer.parseInt(num.getText());
String sResult = "";
for (int i = iNum; i >= 1; --i) {
for (int j = 1; j <= i; ++j) {
// System.out.print(j + " ");
sResult = sResult + (j+" ");
}
// System.out.println();
sResult = sResult + "\n";
}
result.setText(sResult);
}
Note that it is far more efficient to use a StringBuilder instead of building up strings by concatenation (basically, in Java, you should never repeatedly perform string concatenation on the same string in a loop):
public void buttonPressed() {
int iNum = Integer.parseInt(num.getText());
StringBuilder text = new StringBuilder();
for (int i = iNum; i >= 1; --i) {
for (int j = 1; j <= i; ++j) {
text.append(j).append(" ");
}
text.append("\n");
}
result.setText(text.toString());
}