if-else-if: getting an unexpected negative output

Question

So i have this program, where when I select the area and type, the DP will generate.

The problem is, when I select another type (tipe-45 and tipe-54), the result is showed in minus. What is the problem?

if(rb1.isSelected() && t1.isSelected()){
        hargabangunan.setText("90000000");
        luas_tanah_asli.setText("60");}
    else if(rb1.isSelected() && t2.isSelected()){
        hargabangunan.setText("120000000");
        luas_tanah_asli.setText("90");}
    else if(rb1.isSelected() && t3.isSelected()){
        hargabangunan.setText("150000000");
        luas_tanah_asli.setText("110");}
    
    else if(rb2.isSelected() && t1.isSelected()){
        hargabangunan.setText("100000000");
        luas_tanah_asli.setText("70");}
    else if(rb2.isSelected() && t2.isSelected()){
        hargabangunan.setText("130000000");
        luas_tanah_asli.setText("110");}
    else if(rb2.isSelected() && t3.isSelected()){
        hargabangunan.setText("170000000");
        luas_tanah_asli.setText("120");}
   
    else if(rb3.isSelected() && t1.isSelected()){
        hargabangunan.setText("120000000");
        luas_tanah_asli.setText("80");}
    else if(rb3.isSelected() && t2.isSelected()){
        hargabangunan.setText("140000000");
        luas_tanah_asli.setText("120");}
    else if(rb3.isSelected() && t3.isSelected()){
        hargabangunan.setText("200000000");
        luas_tanah_asli.setText("140");}
    
    int htl = hargat*75/100;     
    tst.setText(Integer.toString(htl));
    
    int lta = Integer.parseInt(luas_tanah_asli.getText());
    int ltth = ltt - lta;
    tsa.setText(Integer.toString(ltth));
    
    int hga = Integer.parseInt(hargabangunan.getText());
    int hgaa = hga+lta*hargat+ltth*htl;
    harga.setText(Integer.toString(hgaa));
   
    String hharga;
    hharga = harga.getText();
    int tharga = Integer.parseInt(hharga);
    int dp = tharga*20/100;
    dpf.setText(Integer.toString(dp));

You are doing calculations with some rather large numbers there. Have you checked if what you are trying to calculate even fits in the `int` datatype? Maybe the numbers are to big and you are experiencing [integer overflow](https://stackoverflow.com/questions/3001836/how-does-java-handle-integer-underflows-and-overflows-and-how-would-you-check-fo) — OH GOD SPIDERS, Oct 04 '22 at 09:02
As a quick fix: try changing all your `int` variables to `long`. It might only be needed on the `hga` and `hgaa` variables, but it just might to the trick. — f1sh, Oct 04 '22 at 09:22
changing to 'long', its work. Guess Im forget about this data type. thanks anyway — HERI, Oct 04 '22 at 09:35

score 0 · Answer 1 · answered Oct 04 '22 at 20:23

You are using int but you should use long. Integer can't be used in here as the value is just too big and overflows.

Check https://docs.oracle.com/javase/tutorial/java/nutsandbolts/datatypes.html to see available data types and compare maximum values that you can fit into them.

Use Math.exact and similar methods to immediately get an exception when value overflows. See How can I detect integer overflow on 32 bits int?

if-else-if: getting an unexpected negative output

1 Answers1