安卓常用UI控件的使用方法

1.TextView（文本框）

 <TextView
        android:id="@+id/text_view"
        android:layout_width="match_parent" <!--和父布局大小一致-->
        android:layout_height="wrap_content"<!--刚好包住里面的内容-->
        android:gravity="center" <!--居中-->
        android:text="This is TextView"
        android:textColor="#00ff00"
        android:textSize="24sp" />

2.Button（按钮）

   <Button
        android:id="@+id/button"
        android:text="Button"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:textAllCaps="false"/>

注册监听器

方法一：匿名类

public class MainActivity extends AppCompatActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        Button button = (Button) findViewById(R.id.button);
        button.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                //内容
            }
        });
    }
}

方法二：使用实现接口

public class MainActivity extends AppCompatActivity {

    @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:
                //添加逻辑
                break;
            default:
                break;
        }
    }
}

3.EditText

允许用户在控件里输入和编辑内容，并可以在程序中对这些内容进行处理

  <EditText
        android:id="@+id/edit_text"
        android:hint="Type something there"<!--提示性文本-->
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:maxLines="2"<!--最大行数为2行-->
  />

按一下按钮，弹出提示文本

public class MainActivity extends AppCompatActivity implements View.OnClickListener //entends类，implement接口
{

    private EditText editText;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        Button button = (Button) findViewById(R.id.button);
        editText = (EditText) findViewById(R.id.edit_text);
        button.setOnClickListener(this);
    }
    @Override
    public void onClick(View v){
        switch (v.getId()){
            case R.id.button:
                String inputText = editText.getText().toString(); //转换成字符串
                Toast.makeText(MainActivity.this,inputText,Toast.LENGTH_SHORT).show();//注意toast的用法
                break;
            default:
                break;
        }
    }
}

4.ImageView（图片）

  <ImageView
        android:id="@+id/image_view"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:src="@drawable/img_1"/> <!--指定一张图片-->

按一下按钮换图片

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:
               imageView.setImageResource(R.drawable.img_2);
                break;
            default:
                break;
        }
    }
}

5.ProgressBar（进度条）

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

按一下按钮，改变进度条状态

public class MainActivity extends AppCompatActivity implements View.OnClickListener{

    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){
                    progressBar.setVisibility(View.VISIBLE);
                }else{
                    progressBar.setVisibility(View.GONE);
                }
                break;
            default:
                break;
        }
    }
}

控件的可见属性（使用android:visibility指定）：

visible：可见

invisible：不可见，但仍占据着屏幕的空间（透明）

gone：不可见，不占据屏幕空间

水平进度条

    <ProgressBar
        android:id="@+id/progress_bar"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        style="?android:attr/progressBarStyleHorizontal"
        android:max="100"/>

每按一次按钮，进度条加10

public class MainActivity extends AppCompatActivity implements View.OnClickListener{

    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:
                int progress = progressBar.getProgress();
                progress = progress + 10;
                progressBar.setProgress(progress);
                break;
            default:
                break;
        }
    }
}

6.AlertDialog（弹出对话框）

public class MainActivity extends AppCompatActivity implements View.OnClickListener{

    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:
                AlertDialog.Builder dialog = new AlertDialog.Builder(MainActivity.this);
                dialog.setTitle("This is Dialog"); //对话框标题
                dialog.setMessage("Something important"); //对话框内容
                dialog.setCancelable(false);//可否用back键关闭对话框
                dialog.setPositiveButton("OK", new DialogInterface.OnClickListener() { //设置确认按钮点击事件
                    @Override
                    public void onClick(DialogInterface dialog, int which) {

                    }
                });
                dialog.setNegativeButton("Cancel", new DialogInterface.OnClickListener() { //设置取消按钮点击事件
                    @Override
                    public void onClick(DialogInterface dialog, int which) {

                    }
                });
                dialog.show(); //显示对话框

                break;
            default:
                break;
        }
    }
}

7.ProgressDialog（弹出带进度条的对话框）

public class MainActivity extends AppCompatActivity implements View.OnClickListener{

    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:
                ProgressDialog progressDialog = new ProgressDialog(MainActivity.this);
                progressDialog.setTitle("This is a ProgressDialog");
                progressDialog.setMessage("Loading...");
                progressDialog.setCancelable(true);
                progressDialog.show();
                break;
            default:
                break;
        }
    }
}