要实现材料设计底部菜单半展开状态，可以分为以下步骤：

1.首先，在XML layout文件中定义BottomSheetBehavior和BottomSheet的FrameLayout，以及放置在底部的内容View。

    

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2.在Java代码中，定义BottomSheetBehavior的状态和高度变化监听器，以及动态计算BottomSheet的高度方法。

CoordinatorLayout coordinatorLayout = (CoordinatorLayout) findViewById(R.id.coordinator_layout); FrameLayout bottomSheet = (FrameLayout) coordinatorLayout.findViewById(R.id.bottom_sheet);

final BottomSheetBehavior behavior = BottomSheetBehavior.from(bottomSheet); behavior.setState(BottomSheetBehavior.STATE_HALF_EXPANDED);

behavior.setBottomSheetCallback(new BottomSheetBehavior.BottomSheetCallback() {

@Override
public void onStateChanged(@NonNull View bottomSheet, int newState) {
    // React to state changes
}

@Override
public void onSlide(@NonNull View bottomSheet, float slideOffset) {
    // React to height changes
}

});

int peekHeight = getResources().getDisplayMetrics().heightPixels / 2; behavior.setPeekHeight(peekHeight);

int contentHeight = ... // Calculate the height of content_view behavior.setHideable(false); behavior.setPeekHeight(peekHeight); behavior