原创

Android滚动条

17. ScrollView(滚动条)

滚动条.png

activity_main.xml:

<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout 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"
    tools:context=".MainActivity">

    <!--
    ScrollView:滚动条
    -->

    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:orientation="vertical">

        <Button
            android:id="@+id/btn_up"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:text="滚到顶部" />

        <Button
            android:id="@+id/btn_down"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:text="滚到底部" />

        <ScrollView
            android:id="@+id/scrollView"
            android:layout_width="match_parent"
            android:layout_height="match_parent">

            <LinearLayout
                android:layout_width="match_parent"
                android:layout_height="wrap_content"
                android:orientation="vertical" >

                <TextView
                    android:id="@+id/txt_show"
                    android:layout_width="wrap_content"
                    android:layout_height="wrap_content"
                    android:text="Hello World!" />
            </LinearLayout>
        </ScrollView>
    </LinearLayout>

</androidx.constraintlayout.widget.ConstraintLayout>

MainActivity.java:

package com.lzhpo.scrollview;

import androidx.appcompat.app.AppCompatActivity;

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

public class MainActivity extends AppCompatActivity implements View.OnClickListener {

    private Button btn_down;
    private Button btn_up;
    private ScrollView scrollView;
    private TextView txt_show;

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        bindViews();
    }

    private void bindViews() {
        btn_down = (Button) findViewById(R.id.btn_down);
        btn_up = (Button) findViewById(R.id.btn_up);
        scrollView = (ScrollView) findViewById(R.id.scrollView);
        txt_show = (TextView) findViewById(R.id.txt_show);
        btn_down.setOnClickListener(this);
        btn_up.setOnClickListener(this);

        StringBuilder sb = new StringBuilder();
        for (int i = 1; i <= 100; i++) {
            sb.append("呵呵 * " + i + "\n");
        }
        txt_show.setText(sb.toString());

    }

    @Override
    public void onClick(View v) {
        switch (v.getId()) {
            case R.id.btn_down:
                scrollView.fullScroll(ScrollView.FOCUS_DOWN);
                break;
            case R.id.btn_up:
                scrollView.fullScroll(ScrollView.FOCUS_UP);
                break;
        }
    }
}
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