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javamultidimensional-arrayjtextarea

How do I print a 2d array?


My array is:

String[][] name = new String[15][2];
int rowNumber = 0;

My add button is:

name[rowNumber][0] = firstName.getText();
name[rowNumber][1] = lastName.getText();

I do not know what to put in my list button (lists the first name and last name) into my TextArea called outPut.

The Whole Code:

`
public class StudentGradesView extends FrameView {
 String[][] name = new String[15][2];
 double[][] testMark = new double[15][4];
 int rowNumber = 0;


    private void btnAddMouseClicked(java.awt.event.MouseEvent evt) {                                    
        name[rowNumber][0] = firstName.getText();
        name[rowNumber][1] = lastName.getText();
        rowNumber ++;
    }                                   

    private void btnListMouseClicked(java.awt.event.MouseEvent evt) {                                     
      String outputStr = "";
for(int i=0; i < rowNumber; i++) {
    outputStr += name[rowNumber][0] + " " + name[rowNumber][1] + "\n";
}outPut.setText(outputStr);
    }                                                                               

}`

Solution

  • Okay, I think I get what you want now.

    First we take the inputs...

    name[numberOfInputs][0] = firstName.getText();
    name[numberOfInputs][1] = lastName.getText();
    numberOfInputs += 1;
    

    Now you want to output this to a textarea...

    String outputStr = "";
    for(int i=0; i < numberOfInputs; i++) {      
        outputStr += name[i][0] + " " + name[i][1] + "\n"; 
    }
    

    Then set your output textarea

    outPut.setText(outputStr);
    

    You are getting nulls because you are specifying a static array size but you (probably) are not filling up the array with test cases up to that amount. So you are printing elements of the array that are simply not populated.

    Edit: for comments.