Android的前期学习（二）——常用控件

Button

• 指定Button的onClick属性方式

1. 指定在layout文件中指定onClick属性：
   android：onClick="click"
   2.然后在activity中实现click这个方法
   public void click（View v）{
   Log.i（“指定onClick属性方式”，“button is clicked”）；
   }

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical"
    tools:context=".MainActivity">


    <TextView
        android:id="@+id/textView4"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:textSize="30sp"
        android:text="按钮被点击了吗？" />

    <Button
        android:id="@+id/button8"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:onClick="click"
        android:text="onClick方式" />
</LinearLayout>

package com.example.linearlayoutdemo;

import androidx.appcompat.app.AppCompatActivity;

import android.os.Bundle;
import android.view.View;
import android.widget.TextView;

public class MainActivity extends AppCompatActivity {
    private TextView textView4;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        textView4=findViewById(R.id.textView4);
    }
    public void click(View v){
        textView4.setText("onclick方式成功");
    }
}

image.png

• 匿名内部类方式
  1.在activity中添加匿名内部类
  btn.setOnClickListener(new View.OnClickListener(){
  @override
  public void onClick(View v){
  Log.i("匿名内部类方式","button is clicked");
  }
  });

package com.example.linearlayoutdemo;

import androidx.appcompat.app.AppCompatActivity;

import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.TextView;

public class MainActivity extends AppCompatActivity {
    private TextView textView4;
    private Button button8;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        textView4=findViewById(R.id.textView4);
        button8=findViewById(R.id.button8);
        button8.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                textView4.setText("匿名内部类处理事件");
            }
        });
    }
}

image.png