1. Custom Scroller
import android.content.Context;
import android.util.DisplayMetrics;

import androidx.annotation.IntDef;
import androidx.recyclerview.widget.LinearSmoothScroller;

public class AdjustLinearSmoothScroller extends LinearSmoothScroller {

    private int scrollType;
    private static float time;
    public static final float DEFAULT_MILLISECONDS_PER_INCH = 25f;


    @IntDef({SNAP_TO_ANY, SNAP_TO_START, SNAP_TO_END})
    public @interface ScrollType {
    }


    public AdjustLinearSmoothScroller(Context context, @ScrollType int scrollType) {
        super(context);
        this.scrollType = scrollType;
    }

    @Override
    protected float calculateSpeedPerPixel(DisplayMetrics displayMetrics) {
        return time / displayMetrics.densityDpi;
    }

    public static void setTime(float milliseconds) {
        time = milliseconds;
    }

    @Override
    protected int getVerticalSnapPreference() {
        returnscrollType; }}Copy the code
  1. Custom LayoutManager
import android.content.Context; import android.util.AttributeSet; import androidx.recyclerview.widget.LinearLayoutManager; import androidx.recyclerview.widget.RecyclerView; import static com.koolearn.toefl2019.ui.recyclerview.AdjustLinearSmoothScroller.DEFAULT_MILLISECONDS_PER_INCH; / * * * Description: can be set rolling speed and definition specifies postion in above or below the layoutmanager * / public class AdjustLinearLayoutManager extends LinearLayoutManager { private int scrollType; privatefloat time = DEFAULT_MILLISECONDS_PER_INCH;

    public AdjustLinearLayoutManager(Context context) {
        super(context);
    }

    public AdjustLinearLayoutManager(Context context, int orientation, boolean reverseLayout) {
        super(context, orientation, reverseLayout);
    }

    public AdjustLinearLayoutManager(Context context, AttributeSet attrs, int defStyleAttr, int defStyleRes) {
        super(context, attrs, defStyleAttr, defStyleRes);
    }


    public void setMillisecondsPerInch(float time) {
        this.time = time;
    }

    public void setScrollType(@AdjustLinearSmoothScroller.ScrollType int scrollType) { this.scrollType = scrollType; } @Override public void smoothScrollToPosition(RecyclerView recyclerView, RecyclerView.State state, int position) { AdjustLinearSmoothScroller.setTime(time); AdjustLinearSmoothScroller scroller = new AdjustLinearSmoothScroller(recyclerView.getContext(), scrollType); scroller.setTargetPosition(position); startSmoothScroll(scroller); }}Copy the code
  1. use
mLayoutManager = new AdjustLinearLayoutManager(this);
mLayoutManager.setScrollType(LinearSmoothScroller.SNAP_TO_START);
mRecyclerView.setLayoutManager(mLayoutManager);
Copy the code

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