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StateSet.javaAPI DocAndroid 1.5 API6202Wed May 06 22:41:56 BST 2009android.util

StateSet

public class StateSet extends Object
State sets are arrays of positive ints where each element represents the state of a {@link android.view.View} (e.g. focused, selected, visible, etc.). A {@link android.view.View} may be in one or more of those states. A state spec is an array of signed ints where each element represents a required (if positive) or an undesired (if negative) {@link android.view.View} state. Utils dealing with state sets. In theory we could encapsulate the state set and state spec arrays and not have static methods here but there is some concern about performance since these methods are called during view drawing.

Fields Summary
public static final int[]
WILD_CARD
Constructors Summary
Methods Summary
public static java.lang.Stringdump(int[] states)

        StringBuilder sb = new StringBuilder();
        
        int count = states.length;
        for (int i = 0; i < count; i++) {
            
            switch (states[i]) {
            case R.attr.state_window_focused:
                sb.append("W ");
                break;
            case R.attr.state_pressed:
                sb.append("P ");
                break;
            case R.attr.state_selected:
                sb.append("S ");
                break;
            case R.attr.state_focused:
                sb.append("F ");
                break;
            case R.attr.state_enabled:
                sb.append("E ");
                break;
            }
        }
        
        return sb.toString();
public static booleanisWildCard(int[] stateSetOrSpec)
Return whether the stateSetOrSpec is matched by all StateSets.

param
stateSetOrSpec a state set or state spec.


                           
         
        return stateSetOrSpec.length == 0 || stateSetOrSpec[0] == 0;
public static booleanstateSetMatches(int[] stateSpec, int[] stateSet)
Return whether the stateSet matches the desired stateSpec.

param
stateSpec an array of required (if positive) or prohibited (if negative) {@link android.view.View} states.
param
stateSet an array of {@link android.view.View} states

        if (stateSet == null) {
            return (stateSpec == null || isWildCard(stateSpec));
        }
        int stateSpecSize = stateSpec.length;
        int stateSetSize = stateSet.length;
        for (int i = 0; i < stateSpecSize; i++) {
            int stateSpecState = stateSpec[i];
            if (stateSpecState == 0) {
                // We've reached the end of the cases to match against.
                return true;
            }
            final boolean mustMatch;
            if (stateSpecState > 0) {
                mustMatch = true;
            } else {
                // We use negative values to indicate must-NOT-match states.
                mustMatch = false;
                stateSpecState = -stateSpecState;
            }
            boolean found = false;
            for (int j = 0; j < stateSetSize; j++) {
                final int state = stateSet[j];
                if (state == 0) {
                    // We've reached the end of states to match.
                    if (mustMatch) {
                        // We didn't find this must-match state.
                        return false;
                    } else {
                        // Continue checking other must-not-match states.
                        break;
                    }
                }
                if (state == stateSpecState) {
                    if (mustMatch) {
                        found = true;
                        // Continue checking other other must-match states.
                        break;
                    } else {
                        // Any match of a must-not-match state returns false.
                        return false;
                    }
                }
            }
            if (mustMatch && !found) {
                // We've reached the end of states to match and we didn't
                // find a must-match state.
                return false;
            }
        }
        return true;
public static booleanstateSetMatches(int[] stateSpec, int state)
Return whether the state matches the desired stateSpec.

param
stateSpec an array of required (if positive) or prohibited (if negative) {@link android.view.View} states.
param
state a {@link android.view.View} state

        int stateSpecSize = stateSpec.length;
        for (int i = 0; i < stateSpecSize; i++) {
            int stateSpecState = stateSpec[i];
            if (stateSpecState == 0) {
                // We've reached the end of the cases to match against.
                return true;
            }
            if (stateSpecState > 0) {
                if (state != stateSpecState) {
                   return false;
                }
            } else {
                // We use negative values to indicate must-NOT-match states.
                if (state == -stateSpecState) {
                    // We matched a must-not-match case.
                    return false;
                }
            }
        }
        return true;
public static int[]trimStateSet(int[] states, int newSize)

        if (states.length == newSize) {
            return states;
        }

        int[] trimmedStates = new int[newSize];
        System.arraycopy(states, 0, trimmedStates, 0, newSize);
        return trimmedStates;