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javaswinglayoutalignmentjsplitpane

JSplitPane ignoring alignment

Hello StackExchange community,

I'm at my wits end about this JSplitPane I'm trying to put into my frame, it is sitting on the right side of my frame instead of filling it up or atleast sitting on the left. If anyone could help me with this issue I'd be very thankful.

See below an image of my problem and the code

The problem area is the pane with "tab1" and "tab2", the divider and the pane on the right side of that divider:

enter image description here

I've tried setting setAlignmentX(Component.LEFT_ALIGNMENT) on all the individual parts of the JSplitPane. I've also tried making a JPanel to hold it and aligning that. All to no avail.

Furthermore, existing information I've been able to find hasn't been relevant, mostly people discussing how to align the contents of the JSplitPane.

The code below is all that is needed to make this frame, if any of you need it to help me out feel free.

package test;

import java.awt.Color;
import java.awt.Component;
import java.util.ArrayList;

import javax.swing.BoxLayout;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JList;
import javax.swing.JPanel;
import javax.swing.JScrollPane;
import javax.swing.JSplitPane;
import javax.swing.JTextField;
import javax.swing.ListSelectionModel;

public class FrameMaker {

    public int x = 0;
    private ArrayList<String> mpLabels;
    private JFrame theFrame;

    public void MakeFrame() {
    theFrame = new JFrame("title");
    theFrame.getContentPane().setLayout(new BoxLayout(theFrame.getContentPane(), BoxLayout.Y_AXIS));

    mpLabels = new ArrayList<String>();


    //label1
    JPanel bgSwitches = new JPanel();
    JLabel calcsLabel = new JLabel("top label, broadened with lines to exaggerate problem-------------------------------------------"); 
    bgSwitches.add(calcsLabel);


    //label2
    JPanel topLevel = new JPanel();
    JLabel textinfo = new JLabel("label below that");
    topLevel.add(textinfo);


    //splitpane tabs
    mpLabels.add("tab1");
    mpLabels.add("tab2");           

    String[] mpLabelsAr = new String[mpLabels.size()];
    JList<String> posL = new JList<String>(mpLabels.toArray(mpLabels.toArray(mpLabelsAr)));
    posL.setSelectionMode(ListSelectionModel.SINGLE_SELECTION);

    //panel inside the right splitpane pane, this is needed for something later.
    JPanel RPanel = new JPanel();
    RPanel.setLayout(new BoxLayout(RPanel, BoxLayout.Y_AXIS));

    JScrollPane scrollPos = new JScrollPane(posL);
    JScrollPane scrollROI = new JScrollPane(RPanel);

    JSplitPane posPanel = new JSplitPane(JSplitPane.HORIZONTAL_SPLIT,scrollPos,scrollROI);
    posPanel.setOneTouchExpandable(false);
    posPanel.setDividerLocation(75);


    //label and textfield
    JLabel msLabel = new JLabel("another label");
    JTextField msField = new JTextField("textfield");
    JPanel buttonPanel = new JPanel();
    buttonPanel.add(msLabel);
    buttonPanel.add(msField);

    bgSwitches.setBackground(new Color(0,0,255));
    theFrame.add(bgSwitches);

    topLevel.setBackground(new Color(0,255,0));
    theFrame.add(topLevel);

    posPanel.setAlignmentX(Component.LEFT_ALIGNMENT);
    posPanel.setBackground(new Color(0,255,255));
    theFrame.add(posPanel);

    buttonPanel.setBackground(new Color(255,0,0));
    theFrame.add(buttonPanel);

    theFrame.pack();
    theFrame.setVisible(true);
    }
}
Solution

  • You need to align all of your other elements to the left as well.

    bgSwitches.setAlignmentX(Component.LEFT_ALIGNMENT);
topLevel.setAlignmentX(Component.LEFT_ALIGNMENT);
buttonPanel.setAlignmentX(Component.LEFT_ALIGNMENT);

    You can also add posPanel.setResizeWeight(VALUE BETWEEN 0 AND 1); to specify what percent of the space the JSplitPane should occupy and it will resize with your window.