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javaswingpositiongridbaglayout

Java Swing GridBagLayout Component Positioning

I am using Swing's GridBagLayout for the fist time and I have so far only added two components to a container, although I intend to add more below vertically. So far, the first component (a JLabel) is positioned correctly at PAGE_START, and I have remembered to set weight attributes for the components' corresponding GridBagConstraints. The second component (a JTextField) however is not positioning as I intended and it being centered in the container rather than moving up underneath the JLabel. I have attempted to use multiple anchor constants including FIRST_LINE_START, PAGE_START, NORTH & NORTHWEST but so far nothing is working.

And so, once again I call for the gifted coders of stackoverflow for help. Below is a snippet of the code and below that is an image of the problem graphically.

    // Instantiate components and configure their corresponding GridBagConstraints attributes
    // refPlusType properties
    refPlusType = new JLabel("<html><h3>"+"Reference"+" - "+"Job Type"+" </h3><hr /></html>");
    refPlusTypeGC = new GridBagConstraints();
    refPlusTypeGC.gridx = 0; // Grid position 
    refPlusTypeGC.gridy = 0;
    refPlusTypeGC.gridwidth = 2; // Number of colums occupied by component
    refPlusTypeGC.insets = new Insets(5, 10, 5, 10); // Specifies margin
    refPlusTypeGC.weightx = 0.1; // Required for anchor to work. 
    refPlusTypeGC.weighty = 0.1; // Required for anchor to work. 
    refPlusTypeGC.anchor = GridBagConstraints.PAGE_START; // Position in container

    // addressLine1 properties
    addressLine1 = new JTextField();
    addressLine1GC = new GridBagConstraints();
    addressLine1GC.gridx = 0; 
    addressLine1GC.gridy = 1;
    addressLine1GC.gridwidth = 2; 
    addressLine1GC.insets = new Insets(0, 10, 0, 10); 
    addressLine1GC.fill = GridBagConstraints.HORIZONTAL; // Specifies component fill Horizontal space
    addressLine1GC.weightx = 0.1; 
    addressLine1GC.weighty = 0.1; 
    addressLine1GC.anchor = GridBagConstraints.FIRST_LINE_START;

    // Add components to this HALLogisticsDetailsPanel
    this.add(refPlusType, refPlusTypeGC);
    this.add(addressLine1, addressLine1GC);

Image below;

enter image description here

Thank you all for any help you can offer.

Solution

  • Okay, I got it. I don't like accepting my own answers but here we go. At the end of the day I am trying to get the whole lot to bunch together properly at the top of the container. Adding weighty attributes to all the components individually means that the remaining space in the container is distributed between all of them (relative to their weighty attribute) therefore spacing them out.

    The answer seems to be that by adding a weighty attribute to the lowest component in the GridBagLayout, the rest of the remaining space is allocated to below the lowest component and therefore pushing all components to the top. By default is seems that when remaining space is allocated to a component based on it's weight, it is allocated below it (at least on the y axis).

    Here is the new code with three components to help demonstrate;

        // Instantiate components and configure their corresponding GridBagConstraints attributes
    // refPlusType properties
    refPlusType = new JLabel("<html><h3>"+"Reference"+" - "+"Job Type"+" </h3><hr /></html>");
    refPlusTypeGC = new GridBagConstraints();
    refPlusTypeGC.gridx = 0; // Grid position 
    refPlusTypeGC.gridy = 0;
    refPlusTypeGC.gridwidth = 2; // Number of colums occupied by component
    refPlusTypeGC.insets = new Insets(5, 10, 5, 10); // Specifies margin

    // addressLine1 properties
    addressLine1 = new JTextField();
    addressLine1GC = new GridBagConstraints();
    addressLine1GC.gridx = 0; 
    addressLine1GC.gridy = 1;
    addressLine1GC.gridwidth = 2; 
    addressLine1GC.insets = new Insets(0, 10, 0, 10); 
    addressLine1GC.fill = GridBagConstraints.HORIZONTAL; // Specifies component fill Horizontal space

    // addressLine2 properties
    addressLine2 = new JTextField();
    addressLine2GC = new GridBagConstraints();
    addressLine2GC.gridx = 0; 
    addressLine2GC.gridy = 2;
    addressLine2GC.gridwidth = 2; 
    addressLine2GC.insets = new Insets(0, 10, 0, 10); 
    addressLine2GC.fill = GridBagConstraints.HORIZONTAL; // Specifies component fill Horizontal space 
    addressLine2GC.weighty = 1; // Required for anchor to work.
    addressLine2GC.anchor = GridBagConstraints.NORTH; // Position in container

    // Add components to this HALLogisticsDetailsPanel
    this.add(refPlusType, refPlusTypeGC);
    this.add(addressLine1, addressLine1GC);
    this.add(addressLine2, addressLine2GC);