Class FlowLayout

java.lang.Object
com.codename1.ui.layouts.Layout
com.codename1.ui.layouts.FlowLayout
public class FlowLayout extends Layout

FlowLayout is the default layout manager for Codename One Containers and Forms. It places components in a row one after another based on their preferred size. When it reaches the edge of the container it will break a line and start a new row.

Form hi = new Form("Flow Layout", new FlowLayout());
hi.add(new Label("First")).
    add(new Label("Second")).
    add(new Label("Third")).
    add(new Label("Fourth")).
    add(new Label("Fifth"));
hi.show();

Since flow layout isn't a constraint based layout it has a bunch of very useful enclose methods that can significantly reduce the code required to create the same UI e.g.:

Container flowLayout = FlowLayout.encloseIn(new Label("First"),
        new Label("Second"),
        new Label("Third"),
        new Label("Fourth"),
        new Label("Fifth"));

This class works nicely for simple elements, however since Codename One doesn't reflow recursively (for performance) it can't accurately handle complex layouts. As a result when an element of varying size is placed in a flow layout this confuses the line breaking logic and fails in odd ways. That is why this layout should only be used for relatively simple use cases.

Flow layout supports aligning the component horizontally and vertically, it defaults to the top left alignment for LTR languages. E.g. the following alignments are supported thru the usage of setAlign & setValign.

E.g. you can align to the center

You can align to the right

You can align to the center and the middle horizontally

There are quite a few additional combinations that are possible with these API's.

  • Constructor Details

    • FlowLayout

      public FlowLayout()
      Creates a new instance of FlowLayout with left alignment

    • FlowLayout

      public FlowLayout(int orientation)

      Creates a new instance of FlowLayout with the given orientation one of LEFT, RIGHT or CENTER

      Parameters
      • orientation: the orientation value

    • FlowLayout

      public FlowLayout(int orientation, int valign)

      Creates a new instance of FlowLayout with the given orientation one of LEFT, RIGHT or CENTER and the vertical orientation

      Parameters

      • orientation: the orientation value

      • valign: the vertical orientation one of Component.TOP/BOTTOM/CENTER

    • FlowLayout

      public FlowLayout(int orientation, int valign, boolean vAlignByRow)

      Creates a new instance of FlowLayout with the given orientation one of LEFT, RIGHT or CENTER and the vertical orientation

      Parameters

      • orientation: the orientation value

      • valign: the vertical orientation one of Component.TOP/BOTTOM/CENTER

      • vAlignByRow: whether vertical alignment should be computed by row elements

  • Method Details

    • encloseIn

      public static Container encloseIn(Component... cmps)

      Shorthand for com.codename1.ui.Component...) with a FlowLayout instance see:

      Container flowLayout = FlowLayout.encloseIn(new Label("First"),
        new Label("Second"),
        new Label("Third"),
        new Label("Fourth"),
        new Label("Fifth"));
      Parameters
      • cmps: the components to enclose in a new container
      Returns

      the new container

    • encloseCenter

      public static Container encloseCenter(Component... cmps)

      Shorthand for Container.encloseIn(new FlowLayout(Component.CENTER), cmps);

      Parameters
      • cmps: the components to enclose in a new container
      Returns

      the new container

    • encloseRight

      public static Container encloseRight(Component... cmps)

      Shorthand for Container.encloseIn(new FlowLayout(Component.RIGHT), cmps);

      Parameters
      • cmps: the components to enclose in a new container
      Returns

      the new container

    • encloseMiddle

      public static Container encloseMiddle(Component... cmps)

      Shorthand for Container.encloseIn(new FlowLayout(Component.LEFT, Component.CENTER), cmps);

      Parameters
      • cmps: the components to enclose in a new container
      Returns

      the new container

    • encloseMiddleByRow

      public static Container encloseMiddleByRow(Component... cmps)

      Shorthand for Container.encloseIn(new FlowLayout(Component.LEFT, Component.CENTER, true), cmps);

      Parameters
      • cmps: the components to enclose in a new container
      Returns

      the new container

    • encloseCenterMiddle

      public static Container encloseCenterMiddle(Component... cmps)

      Shorthand for Container.encloseIn(new FlowLayout(Component.CENTER, Component.CENTER), cmps);

      Parameters
      • cmps: the components to enclose in a new container
      Returns

      the new container

    • encloseCenterMiddleByRow

      public static Container encloseCenterMiddleByRow(Component... cmps)

      Shorthand for Container.encloseIn(new FlowLayout(Component.CENTER, Component.CENTER, true), cmps);

      Parameters
      • cmps: the components to enclose in a new container
      Returns

      the new container

    • encloseRightMiddle

      public static Container encloseRightMiddle(Component... cmps)

      Shorthand for Container.encloseIn(new FlowLayout(Component.RIGHT, Component.CENTER), cmps);

      Parameters
      • cmps: the components to enclose in a new container
      Returns

      the new container

    • encloseRightMiddleByRow

      public static Container encloseRightMiddleByRow(Component... cmps)

      Shorthand for Container.encloseIn(new FlowLayout(Component.RIGHT, Component.CENTER, true), cmps);

      Parameters
      • cmps: the components to enclose in a new container
      Returns

      the new container

    • encloseLeftMiddle

      public static Container encloseLeftMiddle(Component... cmps)

      Shorthand for Container.encloseIn(new FlowLayout(Component.LEFT, Component.CENTER), cmps);

      Parameters
      • cmps: the components to enclose in a new container
      Returns

      the new container

    • encloseLeftMiddleByRow

      public static Container encloseLeftMiddleByRow(Component... cmps)

      Shorthand for Container.encloseIn(new FlowLayout(Component.LEFT, Component.CENTER, true), cmps);

      Parameters
      • cmps: the components to enclose in a new container
      Returns

      the new container

    • encloseBottom

      public static Container encloseBottom(Component... cmps)

      Shorthand for Container.encloseIn(new FlowLayout(Component.LEFT, Component.BOTTOM), cmps);

      Parameters
      • cmps: the components to enclose in a new container
      Returns

      the new container

    • encloseCenterBottom

      public static Container encloseCenterBottom(Component... cmps)

      Shorthand for Container.encloseIn(new FlowLayout(Component.CENTER, Component.BOTTOM), cmps);

      Parameters
      • cmps: the components to enclose in a new container
      Returns

      the new container

    • encloseRightBottom

      public static Container encloseRightBottom(Component... cmps)

      Shorthand for Container.encloseIn(new FlowLayout(Component.RIGHT, Component.BOTTOM), cmps);

      Parameters
      • cmps: the components to enclose in a new container
      Returns

      the new container

    • encloseBottomByRow

      public static Container encloseBottomByRow(Component... cmps)

      Shorthand for Container.encloseIn(new FlowLayout(Component.LEFT, Component.BOTTOM, true), cmps);

      Parameters
      • cmps: the components to enclose in a new container
      Returns

      the new container

    • encloseCenterBottomByRow

      public static Container encloseCenterBottomByRow(Component... cmps)

      Shorthand for Container.encloseIn(new FlowLayout(Component.CENTER, Component.BOTTOM, true), cmps);

      Parameters
      • cmps: the components to enclose in a new container
      Returns

      the new container

    • encloseRightBottomByRow

      public static Container encloseRightBottomByRow(Component... cmps)

      Shorthand for Container.encloseIn(new FlowLayout(Component.RIGHT, Component.BOTTOM, true), cmps);

      Parameters
      • cmps: the components to enclose in a new container
      Returns

      the new container

    • layoutContainer

      public void layoutContainer(Container parent)

      Layout the given parent container children

      Parameters
      • parent: the given parent container
      Specified by:
      layoutContainer in class Layout

    • fillRow

      protected void fillRow(Container target, int width, int start, int end)

      This method tries to fill up the available space in a row. This method is called if isFillRows() returns true.

      Parameters

      • target: the parent container

      • width: the width of the row to fill

      • start: the index of the first component in this row

      • end: the index of the last component in this row

    • getPreferredSize

      public Dimension getPreferredSize(Container parent)

      Returns the container preferred size

      Parameters
      • parent: the parent container
      Returns

      the container preferred size

      Specified by:
      getPreferredSize in class Layout

    • toString

      public String toString()
      Returns a string representation of the object. In general, the toString method returns a string that "textually represents" this object. The result should be a concise but informative representation that is easy for a person to read. It is recommended that all subclasses override this method. The toString method for class Object returns a string consisting of the name of the class of which the object is an instance, the at-sign character `@', and the unsigned hexadecimal representation of the hash code of the object. In other words, this method returns a string equal to the value of: getClass().getName() + '@' + Integer.toHexString(hashCode())
      Overrides:
      toString in class Object

    • isFillRows

      public boolean isFillRows()

      Indicates whether the layout manager should try to fill up the available space in the row

      Returns

      the fillRows

    • setFillRows

      public void setFillRows(boolean fillRows)

      Indicates whether the layout manager should try to fill up the available space in the row

      Parameters
      • fillRows: the fillRows to set

    • getValign

      public int getValign()

      Indicates vertical alignment within the flow layout

      Returns

      Component.TOP/BOTTOM/CENTER

    • setValign

      public void setValign(int valign)

      Indicates vertical alignment within the flow layout

      Parameters
      • valign: one of Component.TOP/BOTTOM/CENTER

    • isValignByRow

      public boolean isValignByRow()

      Returns whether vertical alignment is done internally or externally

      Returns

      whether vertical alignment is done internally or externally

    • setValignByRow

      public void setValignByRow(boolean internal)

      When set to true vertical alignment will be performed by row (components within the container will be aligned vertically to each other in the same row) When set to false (which is default) vertical alignment relates to the alignment of this container in regards to external components

      Parameters
      • internal: true for internal, false otherwise

    • getAlign

      public int getAlign()

      Alignment of the flow layout, defaults to LEFT

      Returns

      the orientation

    • setAlign

      public void setAlign(int orientation)

      Alignment of the flow layout, defaults to LEFT

      Parameters
      • orientation: the orientation to set

    • equals

      public boolean equals(Object o)
      Indicates whether some other object is "equal to" this one. The equals method implements an equivalence relation: It is reflexive: for any reference value x, x.equals(x) should return true. It is symmetric: for any reference values x and y, x.equals(y) should return true if and only if y.equals(x) returns true. It is transitive: for any reference values x, y, and z, if x.equals(y) returns true and y.equals(z) returns true, then x.equals(z) should return true. It is consistent: for any reference values x and y, multiple invocations of x.equals(y) consistently return true or consistently return false, provided no information used in equals comparisons on the object is modified. For any non-null reference value x, x.equals(null) should return false. The equals method for class Object implements the most discriminating possible equivalence relation on objects; that is, for any reference values x and y, this method returns true if and only if x and y refer to the same object (x==y has the value true).
      Overrides:
      equals in class Layout

    • hashCode

      public int hashCode()
      Description copied from class: Layout
      Returns a hash code value for the object. This method is supported for the benefit of hashtables such as those provided by java.util.Hashtable. The general contract of hashCode is: Whenever it is invoked on the same object more than once during an execution of a Java application, the hashCode method must consistently return the same integer, provided no information used in equals comparisons on the object is modified. This integer need not remain consistent from one execution of an application to another execution of the same application. If two objects are equal according to the equals(Object) method, then calling the hashCode method on each of the two objects must produce the same integer result. It is not required that if two objects are unequal according to the equals(java.lang.Object) method, then calling the hashCode method on each of the two objects must produce distinct integer results. However, the programmer should be aware that producing distinct integer results for unequal objects may improve the performance of hashtables. As much as is reasonably practical, the hashCode method defined by class Object does return distinct integers for distinct objects. (This is typically implemented by converting the internal address of the object into an integer, but this implementation technique is not required by the JavaTM programming language.)
      Overrides:
      hashCode in class Layout