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

ImageView替换图片

imageView = (ImageView) findViewById(R.id.imageView);
imageView.setImageResource(R.mipmap.ic_sunshine);

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

  
    
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

title.xml

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 {

private int resourceId;

public FruitAdapter(Context context, int resource, List 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();
                }
            }
    );

参考资料

1.第一行代码-android