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;
        }
    }