Length Converter Calc

[Vinay Berry]

I'm having trouble with some code I'm building a length converter that converts length from 5 text fields if the user enters a value in one text field for say millimeter, then meters, yards, feet and inches should be filled out when the convert button is clicked. I wrote 5 if statements that get text from the field if the field has text in it then it should execute the code. The problem is it doesn't follow these statements it just runs through all the if statements and tries to perform all the operations.

lcalcConvertButton.addMouseListener(new MouseAdapter(){
			public void mouseClicked(MouseEvent e){
				try{
				DecimalFormat num = new DecimalFormat("###.###");
				String conVar;
				double mm=0, m=0, yards=0, feet=0, inches=0;
				if(MmField.getText() != "") {
					conVar = MmField.getText();
					mm = Double.parseDouble(conVar);
					m = mm / 1000;
					yards = mm / 914.4;
					feet = mm / 304.8;
					inches = mm / 25.4;										
				}
				if(MField.getText() != "") {
					conVar = MField.getText();
					m = Double.parseDouble(conVar);
					mm = m * 1000;
					yards = m * 1.094;
					feet = m * 3.281;
					inches = m * 39.37;					
				}
				if(yardsField.getText() != "") {
					conVar = yardsField.getText();
					yards = Double.parseDouble(conVar);
					mm = yards / 914.4;
					m = yards / 1.094;
					feet = yards * 3;
					inches = yards * 36;					
				}
				if(feetField.getText() != "") {
					conVar = feetField.getText();
					feet = Double.parseDouble(conVar);
					mm = feet / 304.8;
					m = feet / 3.281;
					yards = feet / 3;
					inches = feet * 12;					
				}
				if(inchesField.getText() != "") {
					conVar = inchesField.getText();
					inches = Double.parseDouble(conVar);
					mm = inches / 25.4;
					m = inches / 39.37;
					yards = inches / 36;
					feet = inches / 12;
				}
				MmField.setText(num.format(mm));
				MField.setText(num.format(mm));					
				yardsField.setText(num.format(yards));
				feetField.setText(num.format(feet));
				inchesField.setText(num.format(inches));
			}

[Campbell Ritchie]

Don't use == or != for objects, which includes Strings. Use the equals method.

[Vinay Berry]

how can i implement that into the code?

[John de Michele]

Vinay Berry wrote:how can i implement that into the code?

Instead of something like this:

MField.getText() != ""

You would do this:

!MField.getText().equals("")

John.

[Vinay Berry]

Thanks it works now!

[Rob Spoor]

To check for empty Strings you can also use !MField.getText().length() == 0.

[Vinay Berry]

Rob Prime wrote:To check for empty Strings you can also use !MField.getText().length() == 0.

haha we just learned about that method too it probably would've impressed the professor if I used it in my code

[Campbell Ritchie]

You should be looking through the API documentation anyway, so you ought to have found that method.

[Sharon nguyen]

Vinay Berry wrote:I'm having trouble with some code I'm building a length converter that converts length from 5 text fields if the user enters a value in one text field for say millimeter, then meters, yards, feet and inches should be filled out when the convert button is clicked. I wrote 5 if statements that get text from the field if the field has text in it then it should execute the code. The problem is it doesn't follow these statements it just runs through all the if statements and tries to perform all the operations.

Thanks you for the post.
Hi guys, Im a newbie. Nice to join this forum.
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[Campbell Ritchie]

. . . and welcome to JavaRanch ( ), Sharon nguyen