基礎控制元件(ListView,RecyclerView,單位和尺寸,ViewPager,ViewPager2)
阿新 • • 發佈:2021-06-30
ListView
- list_item.xml
<?xml version="1.0" encoding="utf-8"?> <LinearLayout android:layout_height="match_parent" android:layout_width="match_parent" android:orientation="vertical" xmlns:android="http://schemas.android.com/apk/res/android"> <TextView android:id="@+id/tv" android:layout_width="wrap_content" android:layout_height="wrap_content" android:textSize="30sp" android:text="haha"/> </LinearLayout>
- activity_main.xml
<?xml version="1.0" encoding="utf-8"?> <LinearLayout android:layout_height="match_parent" android:layout_width="match_parent" android:orientation="vertical" xmlns:android="http://schemas.android.com/apk/res/android"> <ListView android:id="@+id/lv" android:layout_width="match_parent" android:layout_height="match_parent"/> </LinearLayout>
- Bean.java
package com.example.mylistview;
public class Bean {
String name;
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
}
- MainActivity.java
package com.example.mylistview; import androidx.appcompat.app.AppCompatActivity; import android.os.Bundle; import android.util.Log; import android.view.View; import android.widget.AdapterView; import android.widget.ListView; import java.util.ArrayList; import java.util.List; public class MainActivity extends AppCompatActivity { private List<Bean> data = new ArrayList<>(); @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); for (int i = 0; i < 100; i++) { Bean bean = new Bean(); bean.setName("haha" + i); data.add(bean); } ListView listView = findViewById(R.id.lv); listView.setAdapter(new MyAdapter(data, this)); listView.setOnItemClickListener(new AdapterView.OnItemClickListener() { @Override public void onItemClick(AdapterView<?> adapterView, View view, int i, long l) { Log.e("wmj", "onItemClick:" + i); } }); } }
- 普通版MyAdapter.java
package com.example.mylistview;
import android.content.Context;
import android.util.Log;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.BaseAdapter;
import android.widget.TextView;
import java.util.List;
public class MyAdapter extends BaseAdapter {
private List<Bean> data;
private Context context;
public MyAdapter(List<Bean> data, Context context) {
this.data = data;
this.context = context;
}
@Override
public int getCount() {
return data.size();
}
@Override
public Object getItem(int i) {
return null;
}
@Override
public long getItemId(int i) {
return i;
}
// 每顯示一個item都會呼叫一次
@Override
public View getView(int i, View view, ViewGroup viewGroup) {
if(view == null){
view = LayoutInflater.from(context).inflate(R.layout.list_item, viewGroup, false);
}
TextView textView = view.findViewById(R.id.tv);
textView.setText(data.get(i).getName());
Log.e("wmj", "getView:" + i);
return view;
}
}
- 優化後的My Adapter.java,減少findviewbyid的時間
package com.example.mylistview;
import android.content.Context;
import android.util.Log;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.BaseAdapter;
import android.widget.TextView;
import java.util.List;
public class MyAdapter extends BaseAdapter {
private List<Bean> data;
private Context context;
public MyAdapter(List<Bean> data, Context context) {
this.data = data;
this.context = context;
}
@Override
public int getCount() {
return data.size();
}
@Override
public Object getItem(int i) {
return null;
}
@Override
public long getItemId(int i) {
return i;
}
// 每顯示一個item都會呼叫一次
@Override
public View getView(int i, View view, ViewGroup viewGroup) {
ViewHolder viewHolder;
if(view == null){
viewHolder = new ViewHolder();
view = LayoutInflater.from(context).inflate(R.layout.list_item, viewGroup, false);
viewHolder.textView = view.findViewById(R.id.tv);
view.setTag(viewHolder);
}else{
viewHolder = (ViewHolder) view.getTag();
}
viewHolder.textView.setText(data.get(i).getName());
Log.e("wmj", "getView:" + i);
return view;
}
private final class ViewHolder{
TextView textView;
}
}
RecyclerView
- 在build.gradle中新增依賴:implementation 'androidx.recyclerview:recyclerview:1.1.0'
- recyclerview_item.xml
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout android:layout_height="match_parent"
android:layout_width="match_parent"
android:orientation="vertical"
xmlns:android="http://schemas.android.com/apk/res/android">
<TextView
android:id="@+id/tv"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:textSize="30sp"
android:text="haha"/>
</LinearLayout>
- activity_main.xml
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout android:layout_height="match_parent"
android:layout_width="match_parent"
android:orientation="vertical"
xmlns:android="http://schemas.android.com/apk/res/android">
<androidx.recyclerview.widget.RecyclerView
android:id="@+id/rv"
android:layout_width="match_parent"
android:layout_height="match_parent"/>
</LinearLayout>
- Bean.java
package com.example.myrecyclerview;public class Bean { String name; public String getName() { return name; } public void setName(String name) { this.name = name; }}
- MainActivity.java
package com.example.myrecyclerview;import androidx.appcompat.app.AppCompatActivity;import androidx.recyclerview.widget.GridLayoutManager;import androidx.recyclerview.widget.LinearLayoutManager;import androidx.recyclerview.widget.RecyclerView;import androidx.recyclerview.widget.StaggeredGridLayoutManager;import android.os.Bundle;import android.util.Log;import android.widget.LinearLayout;import java.util.ArrayList;import java.util.List;public class MainActivity extends AppCompatActivity { private List<Bean> data = new ArrayList<>(); @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); for (int i = 0; i < 100; i++) { Bean bean = new Bean(); bean.setName("haha" + i); data.add(bean); } RecyclerView recyclerView = findViewById(R.id.rv); // 設定佈局// LinearLayoutManager linearLayoutManager = new LinearLayoutManager(this);// recyclerView.setLayoutManager(linearLayoutManager); // 引數2是指一行幾個// GridLayoutManager gridLayoutManager = new GridLayoutManager(this, 3);// recyclerView.setLayoutManager(gridLayoutManager); StaggeredGridLayoutManager staggeredGridLayoutManager = new StaggeredGridLayoutManager(3, LinearLayout.VERTICAL); recyclerView.setLayoutManager(staggeredGridLayoutManager); MyAdapter myAdapter = new MyAdapter(data, this); recyclerView.setAdapter(myAdapter); myAdapter.setOnRecyclerItemClickListener(new MyAdapter.OnRecyclerItemClickListener() { @Override public void onRecyclerItemClick(int position) { Log.e("wmj", "onRecyclerItemClick:" + position); } }); }}
- MyAdapter.java
package com.example.myrecyclerview;import android.content.Context;import android.view.View;import android.view.ViewGroup;import android.widget.TextView;import androidx.annotation.NonNull;import androidx.recyclerview.widget.RecyclerView;import java.util.List;public class MyAdapter extends RecyclerView.Adapter<MyAdapter.MyViewHolder> { private List<Bean> data; private Context context; public MyAdapter(List<Bean> data, Context context) { this.data = data; this.context = context; } @NonNull @Override public MyViewHolder onCreateViewHolder(@NonNull ViewGroup parent, int viewType) { View view = View.inflate(context, R.layout.recyclerview_item, null); return new MyViewHolder(view); } @Override public void onBindViewHolder(@NonNull MyAdapter.MyViewHolder holder, int position) { holder.tv.setText(data.get(position).getName()); } @Override public int getItemCount() { return data == null ? 0 : data.size(); } public class MyViewHolder extends RecyclerView.ViewHolder{ private TextView tv; public MyViewHolder(@NonNull View itemView) { super(itemView); tv = itemView.findViewById(R.id.tv); itemView.setOnClickListener(new View.OnClickListener() { @Override public void onClick(View view) { if(onRecyclerItemClickListener != null){ onRecyclerItemClickListener.onRecyclerItemClick(getAdapterPosition()); } } }); } } // 點選監聽 private OnRecyclerItemClickListener onRecyclerItemClickListener; public void setOnRecyclerItemClickListener(OnRecyclerItemClickListener onRecyclerItemClickListener) { this.onRecyclerItemClickListener = onRecyclerItemClickListener; } public interface OnRecyclerItemClickListener{ void onRecyclerItemClick(int position); }}
單位和尺寸
package com.example.mylayoutparams;import androidx.appcompat.app.AppCompatActivity;import android.os.Bundle;import android.view.ViewGroup;import android.widget.LinearLayout;import android.widget.TextView;public class MainActivity extends AppCompatActivity { @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState);// setContentView(R.layout.activity_main); LinearLayout linearLayout = new LinearLayout(this); LinearLayout.LayoutParams layoutParams = new LinearLayout.LayoutParams(ViewGroup.LayoutParams.MATCH_PARENT, ViewGroup.LayoutParams.MATCH_PARENT); linearLayout.setLayoutParams(layoutParams); TextView textView = new TextView(this); textView.setText("文字框"); textView.setBackgroundColor(0xffff0000); // 單位預設是畫素px ViewGroup.LayoutParams textLayoutParams = new LinearLayout.LayoutParams(300,300);// textView.setLayoutParams(textLayoutParams);// linearLayout.addView(textView); linearLayout.addView(textView, textLayoutParams); setContentView(linearLayout); }}
ViewPager
- 定義一個viewpager
- 為viewpager構建Adapter
- layout1.xml
<?xml version="1.0" encoding="utf-8"?><LinearLayout android:layout_height="match_parent" android:layout_width="match_parent" android:orientation="vertical" android:background="#00ff00" xmlns:android="http://schemas.android.com/apk/res/android"> <TextView android:layout_width="wrap_content" android:layout_height="wrap_content" android:text="layout1" android:textSize="30sp"/></LinearLayout>
- activity_main.xml
<?xml version="1.0" encoding="utf-8"?><LinearLayout android:layout_height="match_parent" android:layout_width="match_parent" android:orientation="vertical" xmlns:android="http://schemas.android.com/apk/res/android"> <androidx.viewpager.widget.ViewPager android:id="@+id/vp" android:layout_width="match_parent" android:layout_height="match_parent"/></LinearLayout>
- MainActivity.java
package com.example.myviewpager;import androidx.appcompat.app.AppCompatActivity;import androidx.viewpager.widget.ViewPager;import android.os.Bundle;import android.view.LayoutInflater;import android.view.View;import java.util.ArrayList;import java.util.List;public class MainActivity extends AppCompatActivity { @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); LayoutInflater lf = getLayoutInflater().from(this); View view1 = lf.inflate(R.layout.layout1, null); View view2 = lf.inflate(R.layout.layout2, null); View view3 = lf.inflate(R.layout.layout3, null); List<View> viewList = new ArrayList<>(); viewList.add(view1); viewList.add(view2); viewList.add(view3); ViewPager viewPager = findViewById(R.id.vp); MyAdapter myAdapter = new MyAdapter(viewList); viewPager.setAdapter(myAdapter); }}
- MyAdapter.java
package com.example.myviewpager;import android.view.View;import android.view.ViewGroup;import androidx.annotation.NonNull;import androidx.viewpager.widget.PagerAdapter;import java.util.List;public class MyAdapter extends PagerAdapter { List<View> mListView; public MyAdapter(List<View> mListView) { this.mListView = mListView; } @Override public int getCount() { return mListView.size(); } // 將給定位置的view新增到viewgroup容器中,建立並顯示出來 @NonNull @Override public Object instantiateItem(@NonNull ViewGroup container, int position) { container.addView(mListView.get(position), 0); return mListView.get(position); } @Override public boolean isViewFromObject(View view,Object object) { return view == object; } @Override public void destroyItem(@NonNull ViewGroup container, int position, @NonNull Object object) { container.removeView(mListView.get(position)); }}
ViewPager2
- 新增依賴:implementation 'androidx.viewpager2:viewpager2:1.0.0'
- activity_main.xml
<?xml version="1.0" encoding="utf-8"?><LinearLayout android:layout_height="match_parent" android:layout_width="match_parent" android:orientation="vertical" xmlns:android="http://schemas.android.com/apk/res/android"> <androidx.viewpager2.widget.ViewPager2 android:id="@+id/vp" android:background="#ffff00" android:layout_width="match_parent" android:layout_height="match_parent"/></LinearLayout>
- item_pager.xml
<?xml version="1.0" encoding="utf-8"?><RelativeLayout android:layout_height="match_parent" android:layout_width="match_parent" android:id="@+id/container" xmlns:android="http://schemas.android.com/apk/res/android"> <TextView android:layout_width="wrap_content" android:layout_height="wrap_content" android:layout_centerInParent="true" android:id="@+id/tvTitle" android:text="haha" android:textColor="#ff0000"/></RelativeLayout>
- MainActivity.java
package com.example.myviewpager2;import androidx.appcompat.app.AppCompatActivity;import androidx.viewpager2.widget.ViewPager2;import android.os.Bundle;public class MainActivity extends AppCompatActivity { @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); ViewPager2 viewPager = findViewById(R.id.vp); ViewPagerAdapter viewPagerAdapter = new ViewPagerAdapter(); viewPager.setAdapter(viewPagerAdapter); }}
- ViewPagerAdapter.java
package com.example.myviewpager2;import android.graphics.drawable.Drawable;import android.view.LayoutInflater;import android.view.View;import android.view.ViewGroup;import android.widget.RelativeLayout;import android.widget.TextView;import androidx.annotation.NonNull;import androidx.recyclerview.widget.RecyclerView;import java.util.ArrayList;import java.util.List;public class ViewPagerAdapter extends RecyclerView.Adapter<ViewPagerAdapter.ViewPagerViewHolder> { private List<String> titles = new ArrayList<>(); private List<Integer> colors = new ArrayList<>(); public ViewPagerAdapter(){ titles.add("haha"); titles.add("xixi"); titles.add("hehe"); titles.add("enen"); colors.add(R.color.white); colors.add(R.color.purple_200); colors.add(R.color.purple_500); colors.add(R.color.purple_700); } @NonNull @Override public ViewPagerViewHolder onCreateViewHolder(@NonNull ViewGroup parent, int viewType) { return new ViewPagerViewHolder(LayoutInflater.from(parent.getContext()).inflate(R.layout.item_pager, parent, false)); } @Override public void onBindViewHolder(@NonNull ViewPagerViewHolder holder, int position) { holder.mTv.setText(titles.get(position)); // 填進去的是資源id holder.mContainer.setBackgroundResource(colors.get(position)); } @Override public int getItemCount() { return 4; } class ViewPagerViewHolder extends RecyclerView.ViewHolder{ private TextView mTv; private RelativeLayout mContainer; public ViewPagerViewHolder(@NonNull View itemView) { super(itemView); mContainer = itemView.findViewById(R.id.container); mTv = itemView.findViewById(R.id.tvTitle); } }}