引言
xml很强大
TextView
Button
语法
添加点击处理
1.第一种
package com.example.diandodo.helloworld;import android.support.v7.app.AppCompatActivity;import android.os.Bundle;import android.util.Log; // 引入可以使用日志import android.view.View;import android.widget.Button;public class HelloWorldActivity extends AppCompatActivity { private static final String TAG = "HelloWorldActivity"; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.hello_world_layout); Button button = (Button) findViewById(R.id.button); button.setOnClickListener(new View.OnClickListener() { @Override public void onClick(View v) { Log.d(TAG,"Click"); } }); }} 2.第二种
package com.example.diandodo.helloworld;import android.support.v7.app.AppCompatActivity;import android.os.Bundle;import android.util.Log; // 引入可以使用日志import android.view.View;import android.widget.Button;public class HelloWorldActivity extends AppCompatActivity implements View.OnClickListener{ private static final String TAG = "HelloWorldActivity"; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.hello_world_layout); Button button = (Button) findViewById(R.id.button); button.setOnClickListener(this); } @Override public void onClick(View v) { switch (v.getId()) { case R.id.button: Log.d(TAG,"Click"); break; } }} EditText
允许用户输入和编辑内容
小案例，点击获取内容
1.布局
2.业务
package com.example.diandodo.helloworld;import android.support.v7.app.AppCompatActivity;import android.os.Bundle;import android.util.Log; // 引入可以使用日志import android.view.View;import android.widget.Button;import android.widget.EditText;import android.widget.Toast;public class HelloWorldActivity extends AppCompatActivity implements View.OnClickListener{ private static final String TAG = "HelloWorldActivity"; private EditText editText; // 定义一个全局变量 @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.hello_world_layout); 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(); Toast.makeText(HelloWorldActivity.this,inputText,Toast.LENGTH_SHORT).show(); break; } }} ImageView
图片展示的控件。
图片通常放在以“drawable”开头的目录下。
小案例，点击更改图片
1.布局
2.业务
package com.example.diandodo.helloworld;import android.support.v7.app.AppCompatActivity;import android.os.Bundle;import android.util.Log; // 引入可以使用日志import android.view.View;import android.widget.Button;import android.widget.EditText;import android.widget.ImageView;import android.widget.Toast;public class HelloWorldActivity extends AppCompatActivity implements View.OnClickListener{ private static final String TAG = "HelloWorldActivity"; private EditText editText; // 定义一个全局变量 private ImageView imageView; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.hello_world_layout); editText = (EditText) findViewById(R.id.edit_text); imageView= (ImageView) findViewById(R.id.image_view); Button button = (Button) findViewById(R.id.button); Button button_change_img = (Button) findViewById(R.id.button_change_img); button.setOnClickListener(this); button_change_img.setOnClickListener(this); } @Override public void onClick(View v) { switch (v.getId()) { case R.id.button: String inputText = editText.getText().toString(); Toast.makeText(HelloWorldActivity.this,inputText,Toast.LENGTH_SHORT).show(); break; case R.id.button_change_img: imageView.setImageResource(R.drawable.img_2); break; } }} ProgressBar
进度条
小案例，点击隐藏显示进度条
1.布局
2.业务
package com.example.diandodo.helloworld;import android.support.v7.app.AppCompatActivity;import android.os.Bundle;import android.util.Log; // 引入可以使用日志import android.view.View;import android.widget.Button;import android.widget.EditText;import android.widget.ImageView;import android.widget.ProgressBar;import android.widget.Toast;public class HelloWorldActivity extends AppCompatActivity implements View.OnClickListener{ private static final String TAG = "HelloWorldActivity"; private EditText editText; // 定义一个全局变量 private ImageView imageView; private ProgressBar progressBar; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.hello_world_layout); editText = (EditText) findViewById(R.id.edit_text); imageView= (ImageView) findViewById(R.id.image_view); progressBar = (ProgressBar) findViewById(R.id.progress_bar); Button button = (Button) findViewById(R.id.button); Button button_change_img = (Button) findViewById(R.id.button_change_img); Button button_set_view = (Button) findViewById(R.id.button_set_view); button.setOnClickListener(this); button_change_img.setOnClickListener(this); button_set_view.setOnClickListener(this); } @Override public void onClick(View v) { switch (v.getId()) { case R.id.button: String inputText = editText.getText().toString(); Toast.makeText(HelloWorldActivity.this,inputText,Toast.LENGTH_SHORT).show(); break; case R.id.button_change_img: imageView.setImageResource(R.drawable.img_2); break; case R.id.button_set_view: if (progressBar.getVisibility() == View.GONE) { progressBar.setVisibility(View.VISIBLE); // INVISIBLE } else { progressBar.setVisibility(View.GONE); } break; } }} 设为长的进度条
1.布局调整
2.业务处理
@Override public void onClick(View v) { switch (v.getId()) { case R.id.button: String inputText = editText.getText().toString(); Toast.makeText(HelloWorldActivity.this,inputText,Toast.LENGTH_SHORT).show(); break; case R.id.button_change_img: imageView.setImageResource(R.drawable.img_2); break; case R.id.button_set_view:// if (progressBar.getVisibility() == View.GONE) {// progressBar.setVisibility(View.VISIBLE); // INVISIBLE// } else {// progressBar.setVisibility(View.GONE);// } int progress = progressBar.getProgress(); progress = progress + 10; progressBar.setProgress(progress); break; } } 这样每次点击，都会增加进度。
AlertDialog
弹出对话框，置顶于所有界面元素之上。
AlertDialog.Builder dialog = new AlertDialog.Builder(HelloWorldActivity.this); dialog.setTitle("这是Dialog"); dialog.setMessage("一些重要的事情"); 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
会在对话框中显示一个进度条，一般用于表示当前操作比较耗时，让用户耐心等待。
ProgressDialog progressDialog = new ProgressDialog(HelloWorldActivity.this); progressDialog.setTitle("这是progressDialog"); progressDialog.setMessage("Loading..."); progressDialog.setCancelable(true); progressDialog.show();