findViewById returns null

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findViewById returns null

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I'm getting null from my findViewById call, and I can not figure out why. The code below is relative to Activity in my program:

 @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        //setContentView(R.layout.dashboard);
        getLayoutInflater().inflate(R.layout.activity_cpc_select, frameLayout);

        TreeNode root = TreeNode.root();
        TreeNode parent = new TreeNode("MyParentNode");
        TreeNode child0 = new TreeNode("ChildNode0");
        TreeNode child1 = new TreeNode("ChildNode1");
        parent.addChildren(child0, child1);
        root.addChild(parent);

        AndroidTreeView tView = new AndroidTreeView(this, root);
        FrameLayout view= (FrameLayout) findViewById(R.id.cpc_tree_view);
        view.addView(tView.getView());    
    }

My layout is defined like this:

<FrameLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent">

    <FrameLayout
        android:id="@+id/cpc_tree_view"
        android:layout_width="match_parent"
        android:layout_height="match_parent">

    </FrameLayout>
</FrameLayout>

java android

asked by anonymous 26.06.2017 / 12:12

1 answer

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score 0 · Accepted Answer

The problem is in the commented line of setContentView

Changing your code to:

@Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.dashboard);

        TreeNode root = TreeNode.root();
        TreeNode parent = new TreeNode("MyParentNode");
        TreeNode child0 = new TreeNode("ChildNode0");
        TreeNode child1 = new TreeNode("ChildNode1");
        parent.addChildren(child0, child1);
        root.addChild(parent);

        AndroidTreeView tView = new AndroidTreeView(this, root);
        FrameLayout view= (FrameLayout) findViewById(R.id.cpc_tree_view);
        view.addView(tView.getView());    
    }

you can access the view with findViewById (); According to the documentation, every view that is initialized in an activity must be created with setContentView.