android组件学习笔记（一）
Toast 提示
Toast.makeText(MainActivity.this, "toast content", Toast.LENGTH_SHORT).show();
EditText设置行数
<EditText
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:hint="type something here"
android:maxLines="5"
android:id="@+id/editText" />
ImageView替换图片
imageView = (ImageView) findViewById(R.id.imageView);
imageView.setImageResource(R.mipmap.ic_sunshine);
TextView
<TextView
android:id="@+id/text_view"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:gravity="center"
android:textSize="24sp"
android:textColor="#00ff00"
android:text="This is TextView" />
Button 绑定事件
implements View.OnClickListener
public class MainActivity extends AppCompatActivity implements View.OnClickListener {
private Button button;
private EditText editText;
private ImageView imageView;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
button = (Button) findViewById(R.id.button);
editText = (EditText) findViewById(R.id.editText);
button.setOnClickListener(this);
imageView = (ImageView) findViewById(R.id.imageView);
}
@Override
public void onClick(View v) {
switch (v.getId()) {
case R.id.button:
imageView.setImageResource(R.mipmap.ic_sunshine);
break;
default:
break;
}
}
}
或者通过
findViewById(R.id.button).setOnClickListener()这种匿名类来实现
findViewById(R.id.btnMode).setOnClickListener(
new View.OnClickListener() {
@Override
public void onClick(View v) {
Intent intent = new Intent(FirstActivity.this, FirstActivity.class);
startActivity(intent);
}
}
);
progressBar 隐藏和进度控制
隐藏
progressBar = (ProgressBar) findViewById(R.id.progressBar);
if (progressBar.getVisibility() == View.GONE) {
progressBar.setVisibility(View.VISIBLE);
} else {
progressBar.setVisibility(View.GONE);
}
进度控制
<ProgressBar
android:layout_width="match_parent"
android:layout_height="wrap_content"
style="?android:attr/progressBarStyleHorizontal"
android:max="100"
android:id="@+id/progressBar" />
int progress = progressBar.getProgress();
progress += 10;
progressBar.setProgress(progress);
AlertDialog
AlertDialog.Builder dialog = new AlertDialog.Builder(MainActivity.this);
dialog.setTitle("this is dialog");
dialog.setMessage("dialog dialog");
//将对话框设为不可取消（不能使用back键来取消）
dialog.setCancelable(false);
dialog.setPositiveButton("OK", new DialogInterface.OnClickListener() {
@Override
public void onClick(DialogInterface dialog, int which) {
}
});
dialog.setNegativeButton("Cancel", new DialogInterface.OnClickListener() {
@Override
public void onClick(DialogInterface dialog, int which) {
}
});
dialog.show();
ProgressDialog
ProgressDialog dialog = new ProgressDialog
(MainActivity.this);
dialog.setTitle("this is dialog");
dialog.setMessage("Loading...");
dialog.setCancelable(true);
dialog.show();
自定义标题组件
main.xml
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:id="@+id/activity_main"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context="com.example.uicustomviews.MainActivity">
<com.example.uicustomviews.TitleLayout
android:layout_width="match_parent"
android:layout_height="wrap_content">
</com.example.uicustomviews.TitleLayout>
</LinearLayout>
title.xml
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:orientation="horizontal">
<Button
android:id="@+id/title_back"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_gravity="left"
android:layout_margin="5dp"
android:text="Back"
android:textColor="#fff"
/>
<TextView
android:id="@+id/title_text"
android:layout_width="0dp"
android:layout_height="wrap_content"
android:layout_gravity="center"
android:layout_weight="1"
android:text="Title Text"
android:textColor="#fff"
android:textSize="24sp"
/>
<Button
android:id="@+id/title_edit"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_gravity="right"
android:layout_margin="5dip"
android:text="Edit"
android:textColor="#fff"
/>
</LinearLayout>
TitleLayout.java
public class TitleLayout extends LinearLayout {
private android.widget.Button titleBack;
private android.widget.TextView titleText;
private android.widget.Button titleEdit;
public TitleLayout(Context context, AttributeSet attrs) {
super(context, attrs);
LayoutInflater.from(context).inflate(R.layout.title, this);
initView();
titleBack.setOnClickListener(
new OnClickListener() {
@Override
public void onClick(View v) {
((Activity) getContext()).finish();
}
}
);
titleEdit.setOnClickListener(
new OnClickListener() {
@Override
public void onClick(View v) {
Toast.makeText(getContext(), "you clicked edit button",
Toast.LENGTH_SHORT).show();
}
}
);
}
private void initView() {
titleBack = (Button) findViewById(R.id.title_back);
titleText = (TextView) findViewById(R.id.title_text);
titleEdit = (Button) findViewById(R.id.title_edit);
}
}
listview 列表展示
水果展示列表ViewHolder优化
public class FruitAdapter extends ArrayAdapter<Fruit> {
private int resourceId;
public FruitAdapter(Context context, int resource, List<Fruit> objects) {
super(context, resource, objects);
resourceId = resource;
}
@NonNull
@Override
public View getView(int position, View convertView, ViewGroup parent) {
Fruit fruit = getItem(position);
View view;
ViewHolder viewHolder;
if (convertView == null) {
view = LayoutInflater.from(getContext()).inflate(resourceId, null);
viewHolder = new ViewHolder();
viewHolder.fruitImage = (ImageView) view.findViewById(R.id
.fruit_image);
viewHolder.fruitName = (TextView) view.findViewById(R.id
.fruit_name);
view.setTag(viewHolder);
} else {
view = convertView;
viewHolder = (ViewHolder) view.getTag();
}
viewHolder.fruitImage.setImageResource(fruit.getImageId());
viewHolder.fruitName.setText(fruit.getName());
Log.d("fruit", fruit.toString());
return view;
}
class ViewHolder {
ImageView fruitImage;
TextView fruitName;
}
}
adapter数据源
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
initFruits();
FruitAdapter adapter = new FruitAdapter(
MainActivity.this,
R.layout.fruit_item,
fruitList
);
ListView listView = (ListView) findViewById(R.id.list_view);
listView.setAdapter(adapter);
}
列表itemclick事件
listView.setOnItemClickListener(
new AdapterView.OnItemClickListener() {
@Override
public void onItemClick(AdapterView<?> parent, View view,
int position, long id) {
Fruit fruit = fruitList.get(position);
Toast.makeText(MainActivity.this,
fruit.getName(),
Toast.LENGTH_SHORT).show();
}
}
);