自定义View/ViewGroup实现兴趣树效果，奇数条在左，偶数条在右

布局

<?  version=\"1.0\" encoding=\"utf-8\"?>
<LinearLayout  ns:android=\"http://schemas.android.com/apk/res/android\"
     ns:app=\"http://schemas.android.com/apk/res-auto\"
     ns:tools=\"http://schemas.android.com/tools\"
    android:layout_width=\"match_parent\"
    android:layout_height=\"match_parent\"
    tools:context=\".MainActivity\"
    android:orientation=\"vertical\"
    >
    <LinearLayout
        android:layout_width=\"match_parent\"
        android:layout_height=\"wrap_content\"
        android:orientation=\"horizontal\"
        >
        <EditText
            android:id=\"@+id/edit_name\"
            android:layout_width=\"wrap_content\"
            android:layout_height=\"wrap_content\"
            android:hint=\"搜索\"
            android:ems=\"20\"
            />
        <Button
            android:id=\"@+id/button_add\"
            android:layout_width=\"wrap_content\"
            android:layout_height=\"wrap_content\"
            android:text=\"添加\"
            />
    </LinearLayout>
    <com.example.month1.customview.CustomTree
        android:id=\"@+id/custom_tree\"
        android:layout_width=\"match_parent\"
        android:layout_height=\"wrap_content\"
        android:layout_marginTop=\"20dp\"
        ></com.example.month1.customview.CustomTree>

自定义View

public class CustomTree extends LinearLayout {
      private Paint mPaint;
    public CustomTree(Context context) {
        super(context);
        init();

    }

    public CustomTree(Context context, @Nullable AttributeSet attrs) {
        super(context, attrs);
        init();

    }

    private void init() {
        setWillNotDraw(false);
        mPaint=new Paint();
        mPaint.setColor(Color.BLACK);
        mPaint.setStyle(Paint.Style.FILL);
        mPaint.setStrokeWidth(3);
    }

    @Override
    protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
        super.onMeasure(widthMeasureSpec, heightMeasureSpec);
        int widthSize = MeasureSpec.getSize(widthMeasureSpec);
        measureChildren(widthMeasureSpec,heightMeasureSpec);
        int bottom=0;
        int childCount = getChildCount();
        for(int i=0;i<childCount;i++){
            View view = getChildAt(i);
            bottom+=view.getMeasuredHeight();
        }
        setMeasuredDimension(widthSize,bottom);
    }

    @Override
    protected void onLayout(boolean changed, int l, int t, int r, int b) {
        super.onLayout(changed, l, t, r, b);
        int left=0,top=0;
        int childCount = getChildCount();
        for (int i=0;i<childCount;i++){
            View view = getChildAt(i);
            if(i%2==0){
                left=0;
            }else {
                left=getMeasuredWidth()/2;
            }
            view.layout(left,top,left+getMeasuredWidth()/2,top+view.getMeasuredHeight());
            top+=view.getMeasuredHeight();
        }
    }

    @Override
    protected void onDraw(Canvas canvas) {
        super.onDraw(canvas);

        canvas.drawLine(getMeasuredWidth()/2,0,getMeasuredWidth()/2,getMeasuredHeight(),mPaint);
    }
}

activity

public class MainActivity extends AppCompatActivity {

    private EditText editText_name;
    private Button button;
    private CustomTree customTree;

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

        button.set Listener(new View. Listener() {
            @Override
            public void  (View v) {
                TextView textView=new TextView(MainActivity.this);
                textView.setTextColor(Color.RED);
                textView.setText(editText_name.getText().toString());
                textView.setBackgroundResource(R.drawable.search_history_bg);
                textView.setPadding(5,5,5,5);
                customTree.addView(textView);
                customTree.invalidate();
            }
        });
    }

    private void initView(Bundle savedInstanceState) {
        editText_name = findViewById(R.id.edit_name);
        button = findViewById(R.id.button_add);
        customTree = findViewById(R.id.custom_tree);
    }
}