TreeView

Android TreeView is used to display data in tree structures.

TreeView

Overview

The library is designed to support different algorithms. Currently, only the algorithm from Walker (with the runtime improvements from Buchheim) has been implemented. Feel free to contribute. The algorithm should only implement the Algorithm Interface.

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dependencies {
    implementation 'de.blox.treeview:treeview:0.1.0'
}
Groovy

Usage

<LinearLayout
    android:layout_width="match_parent"
    android:layout_height="match_parent">
    <de.blox.treeview.TreeView
     android:id="@+id/treeview"
     android:layout_width="match_parent"
     android:layout_height="match_parent">
    </de.blox.treeview.TreeView>
</LinearLayout>
XML

You can make the node Layout how you like. Just define a layout file, e.g. node.xml ...

<android.support.v7.widget.CardView xmlns:android="http://schemas.android.com/apk/res/android"
                                    xmlns:card_view="http://schemas.android.com/apk/res-auto"
                                    android:id="@+id/card_view"
                                    android:layout_width="match_parent"
                                    android:layout_height="wrap_content"
                                    android:layout_gravity="center"
                                    android:layout_margin="5dp"
                                    card_view:cardBackgroundColor="@android:color/holo_blue_dark"
                                    card_view:cardElevation="16dp"
                                    card_view:contentPadding="10dp">

    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:orientation="vertical">

        <TextView
            android:id="@+id/textView"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:textColor="@android:color/white"
            android:textStyle="bold"/>

    </LinearLayout>
</android.support.v7.widget.CardView>
XML

... and use it with the adapter

public class MainActivity extends AppCompatActivity {
    private int nodeCount = 0;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        TreeView treeView = findViewById(R.id.tree);

        BaseTreeAdapter adapter = new BaseTreeAdapter<ViewHolder>(this, R.layout.node) {
            @NonNull
            @Override
            public ViewHolder onCreateViewHolder(View view) {
                return new ViewHolder(view);
            }

            @Override
            public void onBindViewHolder(ViewHolder viewHolder, Object data, int position) {
                viewHolder.mTextView.setText(data.toString());
            }
        };
        treeView.setAdapter(adapter);
        
        // example tree
        TreeNode rootNode = new TreeNode(getNodeText());
        rootNode.addChild(new TreeNode(getNodeText()));
        final TreeNode child3 = new TreeNode(getNodeText());
        child3.addChild(new TreeNode(getNodeText()));
        final TreeNode child6 = new TreeNode(getNodeText());
        child6.addChild(new TreeNode(getNodeText()));
        child6.addChild(new TreeNode(getNodeText()));
        child3.addChild(child6);
        rootNode.addChild(child3);
        final TreeNode child4 = new TreeNode(getNodeText());
        child4.addChild(new TreeNode(getNodeText()));
        child4.addChild(new TreeNode(getNodeText()));
        rootNode.addChild(child4);

        adapter.setRootNode(rootNode);
    }
    
    private String getNodeText() {
        return "Node " + nodeCount++;
    }
}
Java

ViewHolder class:

    private class ViewHolder {
        TextView mTextView;
        ViewHolder(View view) {
            mTextView = view.findViewById(R.id.textView);
        }
    }
Java

Customization

To use the custom attributes you have to add the namespace first: xmlns:app="http://schemas.android.com/apk/res-auto"

Attribute Format Example Explanation
levelSeparation Dimension 50dp How much space should be used between levels
lineThickness Dimension 10dp Set how thick the connection lines should be
lineColor Color "@android:color/holo_red_dark" Set the color of the connection lines
useMaxSize Boolean true Use the same size for each node

GitHub