Chapter 04: Core APIs
Cheatsheet

Chapter 04 Cheatsheet

String methods

public int length()
 
public char charAt(int index)
 
public int indexOf(int ch)
public int indexOf(int ch, int fromIndex)
public int indexOf(String str)
public int indexOf(String str, int fromIndex)
 
public String substring(int beginIndex)
public String substring(int beginIndex, int endIndex)
 
public String toLowerCase()
public String toUpperCase()
 
public boolean equals(Object obj)
public boolean equalsIgnoreCase(String str)
 
public boolean startsWith(String prefix)
public boolean endsWith(String suffix)
public boolean contains(CharSequence charSeq)
 
public String replace(char oldChar, char newChar)
public String replace(CharSequence target, CharSequence replacement)
 
public String strip()
public String stripLeading()
public String stripTrailing()
public String trim()
 
public String indent(int numberSpace)
public String stripIndent()
 
public String translateEscapes()
 
public boolean isEmpty()
public boolean isBlank()
 
public static String format(String format, Object args...)
public static String format(Locale loc, String format, Object args...)
public String formatted(Object args...) 

StringBuilder methods

public int length()
 
public char charAt(int index)
 
public int indexOf(int ch)
public int indexOf(int ch, int fromIndex)
public int indexOf(String str)
public int indexOf(String str, int fromIndex)
 
public String substring(int beginIndex)
public String substring(int beginIndex, int endIndex)
 
public StringBuilder append(String str)
 
public StringBuilder insert(int offset, String str)
 
public StringBuilder delete(int startIndex, int endIndex)
public Stringbuilder deleteCharAt(int index)
 
public StringBuilder replace(int startIndex, int endIndex, String newString)
 
public StringBuilder reverse()
 
public String intern()

Arrays

  • The size of array is NEVER specified on the left side.

Valid array declarations

  1. int[] myArr;