关于android:Android-开发入门常用控件的使用方法

3.2.1 TextView

<?xml version="1.0" encoding="utf-8"?><LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"    android:orientation="vertical"    android:layout_width="match_parent"    android:layout_height="match_parent">    <TextView        android:id="@+id/text_view"        android:layout_width="match_parent"          #控件宽度        android:layout_height="wrap_content"         #控件高度        android:gravity="center"                     #内容对齐形式        android:textSize="24sp"                      #字体大小，单位sp        android:textColor="#00ff00"                  #字体色彩        android:text="This is TextView" />           #显示的内容

layout_width 和 wrap_content 的可选值：

• match_parent 指定控件大小与父布局一样。
• wrap_content 指定控件大小由控件内容决定。

gravity的可选值：

• top 顶部对齐
• bottom 底部对齐
• left 右边对齐
• right 左边对齐
• center 等同于center_vertical|center_horizontal

3.2.2 Button

<Button    android:id="@+id/button"    android:layout_width="match_parent"    android:layout_height="wrap_content"    android:text="Button"    android:textAllCaps="false" />           #不主动进行大写转换

public class MainActivity extends AppCompatActivity implements View.OnClickListener {    @Override    protected void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.activity_main);        Button button = (Button) findViewById(R.id.button);        button.setOnClickListener(this);    }    @Override    public void onClick(View v) {        switch (v.getId()) {            case R.id.button:                // 按钮点击解决逻辑                break;            default:                break;        }    }}

3.2.3 EditText

<EditText    android:id="@+id/edit_text"    android:layout_width="match_parent"    android:layout_height="wrap_content"    android:hint="Type something here"       #提示性内容    android:maxLines="2"                     #最大可见行数    />

public class MainActivity extends AppCompatActivity implements View.OnClickListener {    private EditText editText;    @Override    protected void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.activity_main);        Button button = (Button) findViewById(R.id.button);        // 获取 EditText 对象        editText = (EditText) findViewById(R.id.edit_text);        button.setOnClickListener(this);    }    @Override    public void onClick(View v) {        switch (v.getId()) {            case R.id.button:                // 获取 EditText 内容                String input = editText.getText().toString();                Toast.makeText(MainActivity.this, inputText, Toast.LENGTH_SHORT).show();                break;            default:                break;        }    }}

3.2.4 ImageView

app/src/main/res/drawable-xhdpi/img_1.png

app/src/main/res/drawable-xhdpi/img_2.png

<ImageView    android:id="@+id/image_view"    android:layout_width="wrap_content"    android:layout_height="wrap_content"    android:src="@drawable/img_1"    />

public class MainActivity extends AppCompatActivity implements View.OnClickListener {    private ImageView imageView;    @Override    protected void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.activity_main);        Button button = (Button) findViewById(R.id.button);        imageView  = (ImageView) findViewById(R.id.image_view);        button.setOnClickListener(this);    }    @Override    public void onClick(View v) {        switch (v.getId()) {            case R.id.button:                // 更换图片                imageView.setImageResource(R.drawable.img_2);                break;            default:                break;        }    }}

3.2.5 ProcessBar

    <ProgressBar        android:id="@+id/progress_bar"        android:layout_width="match_parent"        android:layout_height="wrap_content"        />

public class MainActivity extends AppCompatActivity implements View.OnClickListener {    private EditText editText;    private ImageView imageView;    private ProgressBar progressBar;    @Override    protected void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.activity_main);        Button button = (Button) findViewById(R.id.button);        progressBar = (ProgressBar) findViewById(R.id.progress_bar);        button.setOnClickListener(this);    }    @Override    public void onClick(View v) {        switch (v.getId()) {            case R.id.button:                if (progressBar.getVisibility() == View.GONE) {                    // 显示控件                    progressBar.setVisibility(View.VISIBLE);                } else {                    // 暗藏控件                    progressBar.setVisibility(View.GONE);                }                break;            default:                break;        }    }}

程度进度条：

    <ProgressBar        android:id="@+id/progress_bar"        android:layout_width="match_parent"        android:layout_height="wrap_content"        style="?android:attr/progressBarStyleHorizontal"    #设为程度进度条，默认圆形        android:max="100"                                   #最大值为100        />

    @Override    public void onClick(View v) {        switch (v.getId()) {            case R.id.button:                int progress = progressBar.getProgress();                // 进度+10                progress = progress + 10;                progressBar.setProgress(progress);                break;            default:                break;        }    }

3.2.6 AlertDialog

    @Override    public void onClick(View v) {        switch (v.getId()) {                AlertDialog.Builder dialog = new AlertDialog.Builder(MainActivity.this);                dialog.setTitle("This is a dialog");                dialog.setMessage("something important.");                dialog.setCancelable(false);                // 确定按钮的点击事件                dialog.setPositiveButton("OK", new DiaLogInterface.OnClickListener() {                    @Override                    public void onClick(DiaLogInterface dialog, int whick) {                    }                });                // 勾销按钮的点击事件                dialog.setNegativeButton("Cancel", new DiaLogInterface.OnClickListener() {                    @Override                    public void onClick(DiaLogInterface dialog, int whick) {                    }                });                // 显示dialog                dialog.show();                break;            default:                break;        }    }    

3.2.7 ProgressDialog

    @Override    public void onClick(View v) {        switch (v.getId()) {            case R.id.button:                ProgressDialog progressDialog = new ProgressDialog(MainActivity.this);                progressDialog.setTitle("This is ProgressDialog");                progressDialog.setMessage("Loading...");                // 不能通过返回键勾销，留神要在程序中解决敞开                progressDialog.setCancelable(false);                progressDialog.show();                break;            default:                break;        }    }