现在市面上的很多的应用，都带有下拉列表的功能，将所有选项都放在下拉列表中，当用户点击选择的时候，弹出所有的选项，用户选择一项后，下拉列表自动隐藏，很多下拉列表都是用ListView + PopupWindow来实现的，由于Google推出了替代ListView的RecyclerView，所以简单实现一下：
MainActivity.java
package com.jackie.countdowntimer;
import android.graphics.drawable.BitmapDrawable;
import android.os.Bundle;
import android.os.CountDownTimer;
import android.support.design.widget.FloatingActionButton;
import android.support.design.widget.Snackbar;
import android.support.v7.app.AppCompatActivity;
import android.support.v7.widget.LinearLayoutManager;
import android.support.v7.widget.RecyclerView;
import android.support.v7.widget.Toolbar;
import android.view.View;
import android.widget.EditText;
import android.widget.ImageButton;
import android.widget.PopupWindow;
import java.util.ArrayList;
import java.util.List;
public class MainActivity extends AppCompatActivity implements View.OnClickListener {
private EditText mNumberEditText;
private ImageButton mSelectImageButton;
private PopupWindow mPopupWindow;
private RecyclerView mRecyclerView;
private RecyclerViewAdapter mRecyclerViewAdapter;
private List<String> mNumberList;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
setSupportActionBar(toolbar);
FloatingActionButton fab = (FloatingActionButton) findViewById(R.id.fab);
fab.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
Snackbar.make(view, "Replace with your own action", Snackbar.LENGTH_LONG)
.setAction("Action", null).show();
}
});
//初始化数据
mNumberList = new ArrayList<>();
for (int i = 0; i < 30; i++) {
mNumberList.add("1000000" + i);
}
mNumberEditText = (EditText) findViewById(R.id.number);
mSelectImageButton = (ImageButton) findViewById(R.id.select_number);
mSelectImageButton.setOnClickListener(this);
}
@Override
public void onClick(View v) {
switch (v.getId()) {
case R.id.select_number:
showSelectNumberPopupWindow();
break;
}
}
/**
* 弹出选择号码的对话框
*/
private void showSelectNumberPopupWindow() {
initRecyclerView();
mPopupWindow = new PopupWindow(mRecyclerView, mNumberEditText.getWidth() - 4, 200);
mPopupWindow.setOutsideTouchable(true); // 设置外部可以被点击
mPopupWindow.setBackgroundDrawable(new BitmapDrawable());
mPopupWindow.setFocusable(true); // 使PopupWindow可以获得焦点
// 显示在输入框的左下角
mPopupWindow.showAsDropDown(mNumberEditText, 2, -5);
}
/**
* 初始化RecyclerView，模仿ListView下拉列表的效果
*/
private void initRecyclerView(){
mRecyclerView = new RecyclerView(this);
//设置布局管理器
mRecyclerView.setLayoutManager(new LinearLayoutManager(this));
mRecyclerView.setBackgroundResource(R.drawable.background);
//设置Adapter
mRecyclerViewAdapter = new RecyclerViewAdapter(this, mNumberList);
mRecyclerView.setAdapter(mRecyclerViewAdapter);
//设置点击事件
mRecyclerViewAdapter.setOnItemClickListener(new RecyclerViewAdapter.OnItemClickListener() {
@Override
public void onItemClick(View view, int position) {
mNumberEditText.setText(mNumberList.get(position));
mNumberEditText.setSelection(mNumberEditText.getText().toString().length());
mPopupWindow.dismiss();
}
});
//添加分割线
mRecyclerView.addItemDecoration(new DividerItemDecoration(this, DividerItemDecoration.VERTICAL_LIST));
}
}
RecyclerViewAdapter.java
package com.jackie.countdowntimer;
import android.content.Context;
import android.support.v7.widget.RecyclerView;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ImageButton;
import android.widget.TextView;
import java.util.List;
/**
* Created by Jackie on 2015/12/18.
* RecyclerView Adapter
*/
public class RecyclerViewAdapter extends RecyclerView.Adapter<RecyclerViewAdapter.RecyclerViewHolder> {
private OnItemClickListener mOnItemClickListener;
private Context mContext;
private List<String> mNumberList;
public RecyclerViewAdapter(Context context, List<String> numberList) {
this.mContext = context;
this.mNumberList = numberList;
}
public interface OnItemClickListener {
void onItemClick(View view, int position);
}
public void setOnItemClickListener(OnItemClickListener onItemClickListener) {
this.mOnItemClickListener = onItemClickListener;
}
@Override
public RecyclerViewAdapter.RecyclerViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
RecyclerViewHolder holder = new RecyclerViewHolder(LayoutInflater.from(mContext).inflate(R.layout.number_item, parent, false));
return holder;
}
@Override
public void onBindViewHolder(final RecyclerViewAdapter.RecyclerViewHolder holder, final int position) {
holder.numberTextView.setText(mNumberList.get(position));
// 如果设置了回调，则设置点击事件
if (mOnItemClickListener != null) {
holder.numberTextView.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
mOnItemClickListener.onItemClick(holder.itemView, holder.getLayoutPosition());
}
});
}
holder.deleteImageButton.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
mNumberList.remove(position);
//通知刷新
notifyItemRemoved(position);
}
});
}
@Override
public int getItemCount() {
return mNumberList.size();
}
public class RecyclerViewHolder extends RecyclerView.ViewHolder {
TextView numberTextView;
ImageButton deleteImageButton;
public RecyclerViewHolder(View itemView) {
super(itemView);
numberTextView = (TextView) itemView.findViewById(R.id.number_item);
deleteImageButton = (ImageButton) itemView.findViewById(R.id.number_item_delete);
}
}
}
DividerItemDecoration.java
package com.jackie.countdowntimer;
/*
* Copyright (C) 2014 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* limitations under the License.
*/
import android.content.Context;
import android.content.res.TypedArray;
import android.graphics.Canvas;
import android.graphics.Rect;
import android.graphics.drawable.Drawable;
import android.support.v7.widget.LinearLayoutManager;
import android.support.v7.widget.RecyclerView;
import android.view.View;
/**
* This class is from the v7 samples of the Android SDK. It's not by me!
* <p/>
* See the license above for details.
*/
public class DividerItemDecoration extends RecyclerView.ItemDecoration {
private static final int[] ATTRS = new int[]{
android.R.attr.listDivider
};
public static final int HORIZONTAL_LIST = LinearLayoutManager.HORIZONTAL;
public static final int VERTICAL_LIST = LinearLayoutManager.VERTICAL;
private Drawable mDivider;
private int mOrientation;
public DividerItemDecoration(Context context, int orientation) {
final TypedArray a = context.obtainStyledAttributes(ATTRS);
mDivider = a.getDrawable(0);
a.recycle();
setOrientation(orientation);
}
public void setOrientation(int orientation) {
if (orientation != HORIZONTAL_LIST && orientation != VERTICAL_LIST) {
throw new IllegalArgumentException("invalid orientation");
}
mOrientation = orientation;
}
@Override
public void onDraw(Canvas c, RecyclerView parent) {
if (mOrientation == VERTICAL_LIST) {
drawVertical(c, parent);
} else {
drawHorizontal(c, parent);
}
}
public void drawVertical(Canvas c, RecyclerView parent) {
final int left = parent.getPaddingLeft();
final int right = parent.getWidth() - parent.getPaddingRight();
final int childCount = parent.getChildCount();
for (int i = 0; i < childCount; i++) {
final View child = parent.getChildAt(i);
android.support.v7.widget.RecyclerView v = new android.support.v7.widget.RecyclerView(parent.getContext());
final RecyclerView.LayoutParams params = (RecyclerView.LayoutParams) child.getLayoutParams();
final int top = child.getBottom() + params.bottomMargin;
final int bottom = top + mDivider.getIntrinsicHeight();
mDivider.setBounds(left, top, right, bottom);
mDivider.draw(c);
}
}
public void drawHorizontal(Canvas c, RecyclerView parent) {
final int top = parent.getPaddingTop();
final int bottom = parent.getHeight() - parent.getPaddingBottom();
final int childCount = parent.getChildCount();
for (int i = 0; i < childCount; i++) {
final View child = parent.getChildAt(i);
final RecyclerView.LayoutParams params = (RecyclerView.LayoutParams) child.getLayoutParams();
final int left = child.getRight() + params.rightMargin;
final int right = left + mDivider.getIntrinsicHeight();
mDivider.setBounds(left, top, right, bottom);
mDivider.draw(c);
}
}
@Override
public void getItemOffsets(Rect outRect, int itemPosition, RecyclerView parent) {
if (mOrientation == VERTICAL_LIST) {
outRect.set(0, 0, 0, mDivider.getIntrinsicHeight());
} else {
outRect.set(0, 0, mDivider.getIntrinsicWidth(), 0);
}
}
}
效果图如下：
